JP4954889B2 - Steel sheet for continuous casting enamel that is remarkably excellent in anti-tackiness and method for producing the same - Google Patents

Description

  The present invention relates to an enameled steel plate excellent in enamel characteristics (foam resistance / spot resistance, adhesion, resistance to picking) and processing characteristics and a method for producing the same, and is characterized by being obtained by continuous casting.

Today's enamel steel plates are usually manufactured by a continuous casting process in order to reduce manufacturing costs. And in order to make workability and enamelability compatible, the component adjustment including various additive elements is performed. As an example, it is disclosed in Japanese Patent No. 3260446 and Japanese Patent No. 3358410 that an enamel steel plate having good workability can be produced by B, for example. In this technique, N in steel is fixed as nitride, and B is added as an element capable of imparting good workability. Furthermore, Patent Document 1 discloses that since the deoxidizing ability of B is small, the amount of oxygen in the steel can be kept high. Japanese Patent No. 3613810 is unknown in detail, but B is effective in preventing nail jumping and foaming, and it is effective in preventing abnormal etching of grain boundaries on the steel sheet surface by sulfuric acid washing before enamelling. It is disclosed.
Furthermore, the present inventors tried to improve the enameled steel sheet excellent in tearability and deep drawability containing B, and filed applications in JP-A Nos. 2002-80934 and 2004-18860. The main point of these technologies is that the nitride form is controlled in consideration of Al and hot rolling conditions in addition to B, which is the main nitride controlling element of conventional enamel steel sheets, and the optimum characteristics are built in. However, it is an unprecedented feature. Steel plates made by these techniques not only provide good resistance to tearing, but also use a relatively inexpensive element called B, while suppressing an increase in manufacturing costs, and at the same time being particularly good due to high elongation. Due to its workability, the amount used in the high-end materials market is growing. However, in recent years, the use of steel plates is polarized, that is, materials that are as low as possible are used for general-purpose products. Further workability and enamelability have been required. In particular, there is a strong demand for further improvement in the anti-slipping property, which can be said to be the greatest feature of the enamel steel plate. In order to suppress the entrainment of the enamel steel plate, it is known that it is effective to form voids in the steel plate and trap hydrogen that enters the steel plate during enamel firing here, but simply form voids. This does not necessarily improve the hydrogen trapping ability, and for example, as in Patent Documents 3 and 4, the effect of preferably controlling the form of the nitride was also clear. However, in these conventional steels, it is difficult to say that optimum control is performed from the viewpoint of the amount, shape and nature of the voids by stepping into the oxide form.

The present invention develops the technology of the above-mentioned enamel steel sheet, and by stepping into and controlling not only the nitride but also the oxide form, it is possible to further improve the toughness. It is an object of the present invention to provide a steel sheet for continuous casting enamel, which can be spun and is excellent in resistance to tearing, and a method for producing the same.
The present invention has been obtained by repeatedly investigating various conventional steel plates and steel plate manufacturing methods to the limit. The enamel characteristics of the steel plate for enamel, especially for B-containing steel, the manufacturing conditions, particularly As a result of examining the influence of the melting conditions, the items 1) to 5) were newly found.
That is, for enameling, powder coating (dry) was performed by double enameling treatment with a laxative and upper glaze film thickness of 100 μm, and the pickling property, bubble / spot surface defect, and adhesion were investigated. As a result, the following knowledge was obtained.
1) The anti-tack property tends to become better as the segregation of elements in the oxide increases.
2) Even when the amount of B added is the same, when the segregation of B in the oxide is large, the workability, particularly the r value, tends to be improved.
3) At this time, the addition yield of B which is an expensive additive element is also improved.
4) It is necessary to consider the fluctuation of the element concentration in the oxide even when the oxide is stretched and crushed by rolling and is dispersed.
5) The magnitude of the variation of the element concentration in the oxide can be controlled by the addition of elements during melting, particularly the timing of addition of oxide-forming elements.
The present invention has been completed on the basis of the above findings. In the present invention, oxides having different compositions or integrated oxides in a final product that has undergone a process of rolling in one or both of hot and cold. Even so, it is characterized in that it has a large compositional variation in its interior and that these are present in a particular preferred form. The gist of the present invention is as follows.
(1) In mass%,
C: 0.010% or less,
Mn: 0.03 to 1.30%,
Si: 0.100% or less,
Al: 0.030% or less,
N: 0.0055% or less,
P: 0.035% or less,
S: 0.08% or less,
O: 0.005 to 0.085%,
B: 0.0003 to 0.0250%
The balance is composed of Fe and inevitable impurities, and the oxides of Fe, Mn, Si, Al, and B with a diameter of 0.10 μm or more in the observation unit field of view of 100 μm × 100 μm in the plate cross section are combined and integrated. There are two non-contacting complex oxides having different B mass concentrations, and the highest B mass concentration (B max%) and the lowest B mass concentration (B min%). The ratio of B max / B min ≧ 1.2 is a steel sheet for continuous cast enamel excellent in toughness resistance.
(2) For a composite oxide in which oxides of Fe, Mn, Si, Al, and B having a diameter of 0.10 μm or more in an observation unit visual field of 100 μm × 100 μm in the plate cross section are combined and integrated, the Mn mass concentration is There are any two complex oxides that are not in contact with each other, and the ratio of the highest Mn mass concentration (Mn max%) to the lowest Mn mass concentration (Mn min%) is Mn max / Mn min ≧ The steel plate for continuous cast enamel excellent in toughness resistance according to the above (1), characterized by being 1.2.
(3) Furthermore, in mass%,
Nb: 0.004% less than,
V: 0.003-0.15%
Among them, the steel sheet for continuous cast enamel excellent in toughness resistance according to the above (1) or (2), comprising one or two of them.
(4) Furthermore, in mass%,
Cu: 0.01 to 0.500%,
Excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of the above (1) to (3), characterized in that it contains.
(5) Furthermore, in mass%,
The above (1) characterized by containing 1.0% or less in total of one or more of Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, and Mg. The steel plate for continuous cast enamel excellent in the tear resistance as described in any one of (4).
(6) There is a distribution of B mass concentration in the composite oxide in which one oxide of Fe, Mn, Si, Al, Nb, B, V, and Cr existing in the steel plate is combined and integrated. The ratio of the B mass concentration (B max%) in the high concentration portion to the B mass concentration (B min%) in the low concentration portion is B
max / B min ≧ 1.2 excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of above, wherein (1) to (5) to be.
(7) In the composite oxide in which the oxides of one Fe, Mn, Si, Al, Nb, B, V, and Cr existing in the steel plate are combined and integrated, there is a change in Mn concentration, The ratio of the Mn mass concentration (Mn max%) in the high concentration part to the Mn mass concentration (Mn min%) in the low concentration part is Mn max / Mn min ≧ 1.2. excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of (6).
(8) 1.2 times or more the B mass concentration (%) of the composite oxide in which the oxides of Fe, Mn, Si, Al, Nb, B, V, and Cr inside the plate are combined and integrated Another composite oxide having a B mass concentration of 1 / 1.2 times or less is a straight line distance between the centers of both composite oxides of 0.10 μm or more and within 20 μm, and a straight line connecting the centers of both composite oxides. there at an angle within ± 10 ° from the rolling direction, superior continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of the preceding, characterized in that present (1) to (7).
(9) More than 1.2 times the Mn mass concentration (%) of the composite oxide in which the oxides of Fe, Mn, Si, Al, Nb, B, V, and Cr inside the plate are combined and integrated Another composite oxide having a Mn mass concentration (%) of 1 / 1.2 or less is a linear distance between the centers of both composite oxides of 0.10 μm or more and within 20 μm, and the center of both composite oxides. an angle of the straight line is within ± 10 ° from the rolling direction connecting the above, wherein the present is (1) excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of - (8) .
(10) C: 0.010% or less in mass%,
Mn: 0.03 to 1.3%,
Si: 0.100% or less,
Al: 0.030% or less,
N: 0.0055% or less,
P: 0.035% or less,
S: 0.08% or less,
O: 0.005 to 0.085%,
B: 0.0003 to 0.0250%
And the balance is Fe and inevitable impurities, and in the melting and casting processes of steel, Mn and B are added to molten steel by adding 80% or more of the total amount of Mn by mass%, A method for producing a steel sheet for continuous casting enamel having excellent toughness resistance, characterized by adding at least 80% of the total amount of B added in mass% and casting within 60 minutes.
(11) Furthermore, in mass%,
Nb: 0.004% less than,
V: 0.003-0.15%
1 or 2 type is included, The manufacturing method of the steel plate for continuous cast enamel excellent in the tear resistance as described in said (10) characterized by the above-mentioned.
(12) Further, in mass%,
Cu: 0.01 to 0.500%,
The manufacturing method of the steel plate for continuous casting enamels excellent in the tear resistance as described in said (10) or (11) characterized by including.
(13) Furthermore, in mass%,
The above (10), wherein one or more of Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca and Mg are contained in total of 1.0% or less. -(12) The manufacturing method of the steel plate for continuous casting enamel excellent in the tear resistance as described in any one.
(14) In the casting step, a plate thickness 1/4 layers of the slab, according to any one of the above which is characterized in that a cooling rate ≦ 10 ° C. / sec during solidification (10) - (13) A method for producing a steel sheet for continuous casting enamel with excellent anti-tack resistance.
(15) When a steel piece having an average oxide diameter of 1.0 μm or more and a thickness of 50 mm or more is rolled at a temperature of 600 ° C. or higher, it is true under conditions of 1000 ° C. or higher and a strain rate of 1 / second or higher. The above-mentioned (10), wherein rolling is performed with a total sum of strains of 0.4 or more, and then rolling is performed with a total sum of true strains of 0.7 or more under conditions of 1000 ° C. or less and a strain rate of 10 / sec or more. )-(14) The manufacturing method of the steel plate for continuous cast enamel excellent in the tear resistance as described in any one of .

FIG. 1 is a diagram for explaining the state of an oxide when rolling steel containing a coarse composite oxide having a large concentration difference between B and Mn.
FIG. 2 is a diagram for explaining the state of oxides when rolling steel containing conventional coarse oxides.
FIG. 3 is a diagram for explaining the state of oxides when rolling steel containing fine oxides.
FIG. 4 is a diagram illustrating that when a steel containing a coarse composite oxide having a large concentration difference between B and Mn is rolled, voids around the composite oxide become large.
FIG. 5 is a diagram for explaining that the void around the composite oxide is small when rolling steel containing a coarse composite oxide having no concentration difference.

The present invention is described in detail below.
First, the diameter of the oxide to be controlled in the present invention is set to 0.10 μm or more. Oxides smaller than this range do not need to be subject to special control because the effect of improving the resistance to slipping, that is, the hydrogen permeation-preventing ability, which is a major characteristic of the steel of the present invention, is very small. . Preferably, the characteristics of the oxide described below are recognized even when an oxide of 0.50 μm or more, more preferably 1.0 μm or more, more preferably 2.0 μm or more is targeted. The upper limit of the diameter need not be particularly limited in view of the effect of the present invention. However, although depending on the oxygen content, if the amount of coarse oxides increases, the number density of the oxides decreases and the effect of inhibiting hydrogen permeation decreases. Further, as is generally known, an excessively coarse oxide becomes a crack starting point of a steel sheet during the processing of a product plate and impairs workability. Considering these, the average diameter of the oxide is preferably 15 μm or less, preferably 10 μm or less, and more preferably 5 μm or less.
One of the characteristics of the oxide defined in the present invention is the B concentration of the oxide. In the present invention, it is necessary to specify a high density and a low density, and 100 of 100 μm × 100 μm visual fields having a size of 0.1 μm or more are measured. That is, there are non-integral oxides having different B concentrations in the concentration measured for the oxide in the observation field of 100 μm × 100 μm in the cross section of the plate, and a high concentration B concentration (B max) and a low concentration B concentration ( The ratio of B min) is characterized in that B max / B min ≧ 1.2. When this B concentration ratio is 1.2 or more, as will be described later, the shape change of the oxide during rolling and the accompanying formation of voids are efficiently performed, and as a result, the resistance to sticking becomes remarkable. improves. Preferably, it is 1.5 or more, more preferably 2.0 or more, still more preferably 4.0 or more, and still more preferably 6.0 or more.
Further, the same compositional difference exists in the amount of Mn. That is, non-integral oxides having different Mn concentrations exist in the steel plate within the observation field of 100 μm × 100 μm in the cross section of the plate, and the ratio of the high Mn concentration (Mn max) to the low Mn concentration (Mn min) Is characterized by Mn max / Mn min ≧ 1.2. When the Mn concentration ratio is 1.2 or more, the shape change of the oxide during rolling and the formation of voids accompanying the same can be efficiently performed as in B, and as a result, the resistance to sticking becomes remarkable. improves. Preferably, it is 1.5 or more, more preferably 2.0 or more, still more preferably 4.0 or more, and still more preferably 6.0 or more. A method for measuring the concentration of each element in the oxide for defining the present invention is not particularly limited, but the concentration of each oxide needs to be specified. Further, as will be described later, since it is necessary to regulate the concentration change in one oxide, it is convenient to use, for example, an energy dispersive X-ray dispersive analyzer (EDAX). The measurement method may be a normal method. However, since it is necessary to determine the concentration of a very small region, care should be taken such as sufficiently reducing the beam diameter of the electron beam. Further, it is not necessary to determine the absolute value of the Nb concentration, and it is sufficient if the relative value is known. In the case of using EDAX, the ratio of detection peak heights may be used. It should be noted that the density ratio between the high density portion and the low density portion tends to increase as the size of the measurement region decreases. Ultimately, if the concentration of a region having a size of one atom is measured, it is assumed that the high concentration portion is 100% and the low concentration portion is 0%. In the present invention, an electron beam irradiation area of a general TEM or SEM that is usually used by the present inventor is considered, and an average value in an area of about 0.01 to 0.1 μm is used. . Exactly, there is a spread of the electron beam in the irradiated object, and the information obtained is from a region wider than the set electron beam diameter. In the present invention, it is possible to use a value that can be set to the same diameter as the region where the electron beam diameter is assumed, or to scan the electron beam in a certain minute region and use the average value thereof. It is.
As described above, when there is a difference in concentration in the oxide composition, the reason why the resistance to slipping, that is, the hydrogen permeation preventing ability is improved is not clear, but is considered as follows. It is considered that the oxide dispersed in the steel of the present invention was originally an integral oxide as described later. That is, it is considered that at the time of casting the molten steel whose component adjustment was completed, what was a large oxide was stretched, crushed and finely dispersed. Such stretching and crushing mainly occurs in the rolling process, and in particular, the oxide is mainly stretched in the hot rolling process and is mainly crushed in the cold rolling process. If there is a compositional difference in the oxide in such a process, the degree of stretching differs depending on the oxide part, the oxide shape becomes complicated, and the thinned (thinned) part is preferentially crushed. In addition, it is expected that the portion where the variation in shape is large is preferentially crushed due to the concentration of deformation stress. As a result, the parts having different compositions are efficiently crushed and dispersed. During such efficient crushing, many voids are formed, which serve as hydrogen trap sites in the steel, and significantly improve the hydrogen permeation-preventing ability required for the steel sheet for dredging; It is considered a thing. The above will be specifically described with reference to the drawings. If there is a large concentration difference between B and Mn in the oxide, the coarse composite oxide 1 is crushed by hot rolling 2, stretching 3 and cold rolling 4 as shown in FIG. As a result, the resistance to picking up is improved. On the other hand, in the case of merely containing a complex oxide as in the prior art, the coarse oxide 6 is stretched 3 by hot rolling 2 and cold rolling 4 and is not easily crushed as shown in FIG. Even if it is done, a preferable crushing space | gap cannot be obtained like this invention steel. As shown in FIG. 3, the fine composite oxide 8 in the slab stage is not stretched 9 by hot rolling 2 and cold rolling 4, and is not crushed so much, so that voids 10 are less likely to occur. 1 and 2 show a case where the distance between the crushed complex oxides is relatively short and voids effectively remain between the complex oxides. However, they are stretched and crushed by hot rolling or cold rolling. Even when the voids between the complex oxides formed in this way are crushed and lost by rolling in the same hot rolling or cold rolling process, the effect of the present invention can be sufficiently obtained. This state is schematically shown in FIGS. In the invention steel as shown in FIG. 4 where the composite oxide itself has the same size and arrangement, the composite oxide contains a composite oxide having a large concentration difference between B and Mn and having a large void forming ability. The gap 11 around the slab is also larger, which is preferable for improving the anti-tackiness. In the oxide having the same concentration shown in FIG. In addition, composite oxides having different compositions have a specific relative positional relationship in the steel sheet. That is, a complex oxide exhibiting a high B concentration and a complex oxide exhibiting a low B concentration are 1.2 times the concentration ratio, and the straight line connecting the centers of the complex oxides is within an angle of ± 10 ° from the rolling direction. In addition, the composite is characterized in that it exists within a range of 0.10 μm or more and 20 μm or less in the linear distance between the oxide centers. The angle is preferably within an angle of ± 7 °, more preferably within an angle of ± 5 °, more preferably within an angle of ± 3 °, and is characterized by being arranged linearly in the rolling direction.
Although the reason for this is not clear, it is important that the hydrogen permeation blocking capability required for the steel sheet is to efficiently prevent hydrogen permeation from the center of the steel sheet thickness toward the surface. If they are arranged in the plate thickness direction, a flow of hydrogen in the plate thickness direction is formed through the composite oxide, which is inconvenient for the purpose of the present invention. For this reason, it is presumed that the composite oxide, which is a feature of the present invention, can be further improved in characteristics by being arranged in parallel with the steel plate surface. Needless to say, if it is parallel to the surface of the steel sheet, it is not limited to a specific angle from the rolling direction as described above. However, in a normal manufacturing method, for example, complex oxides are arranged in the sheet width direction. It is difficult to disperse the complex oxide by rolling, and in the present invention, the arrangement is defined by the angle from the rolling direction.
In addition, the distance between the target complex oxides is a linear distance that is within a range of 0.10 μm to 20 μm. If it is out of this range, the anti-patch property deteriorates. The distance is preferably 0.20 μm or more, more preferably 0.30 μm or more, further preferably 0.40 μm or more, and further preferably 0.50 μm or more. The reason why the effect of the invention is affected by the lower limit of the distance is not clear, but there are finer complex oxides and complex oxides with a small concentration difference among the target complex oxides, which prevent hydrogen permeation. It is considered that the performance is influenced by these complex oxides. That is, when the target complex oxides are too close, the entire length of the row-shaped complex oxides having the hydrogen trapping capability is shortened, so that many gaps are generated to stop the flow of hydrogen toward the surface. Therefore, it is considered that the hydrogen permeation blocking ability decreases. Further, the upper limit is preferably 20 μm or less, more preferably 10 μm or less, further preferably 5 μm or less, and further preferably 1 μm or less. The reason for defining the upper limit is that if the target complex oxide is too far away, it is not suitable for the idea of stretching and crushing the coarse complex oxide that was originally integrated, as assumed in the present invention. It is. According to the usual manufacturing method, it arrange | positions within 0.5 micrometer in many cases.
In addition, the effects of the present invention are exhibited even when complex oxides having different compositions are not completely separated. That is, in one complex oxide present in the steel sheet, there is a variation in B concentration, and the ratio between the B concentration (B max) in the high concentration portion and the B concentration (B min) in the low concentration portion is B max. It is sufficient if / B min ≧ 1.2. Preferably, it is 1.5 or more, more preferably 2.0 or more, more preferably 2.5 or more, more preferably 3.0 or more. Similarly, in one composite oxide present in the steel sheet, there is a variation in Mn concentration, and the ratio of the Mn concentration in the high concentration part (Mn max) to the Mn concentration in the low concentration part (Mn min) is It is sufficient if Mn max / Mn min ≧ 1.2. Preferably, it is 1.5 or more, more preferably 2.0 or more, still more preferably 4.0 or more, and still more preferably 6.0 or more.
The reason for this is that, as described above, in the process of stretching and crushing the coarse composite oxide that was originally integral, even if it is not completely separated, at least in a normal observation, it is in a partially bonded state. It is possible. Even in such a case, the shape of the composite oxide becomes very complicated, voids are effectively formed around it, and it acts as a hydrogen trap site, and the deformability of the composite oxide mainly due to the concentration change. Defects formed along the change trap hydrogen and the effects of the present invention can be detected.
In the present invention, it is assumed that a particularly desirable composite oxide exists as a B—Mn—Fe composite oxide. It is a feature of the present invention to optimally control the composition and form (arrangement) of this composite oxide. That is, different composite oxide compositions mean that the composite oxide has different properties, such as hardness and ductility, and has a significant effect on the state of stretching and crushing of the composite oxide during hot rolling and cold rolling. By controlling, it is controlled to a preferable form.
The situation is more complicated when the composite oxide contains many types of elements such as Si, Al, V, Nb, etc., depending on the steel composition and manufacturing conditions, especially the steelmaking conditions and hot rolling heating conditions. Thus, controlling the content of each element in the complex oxide is very important for improving the properties of the steel sheet. Further, when the amount of S is increased, MnS is complex-deposited in the complex oxide, and the effect of the present invention can be made more remarkable due to the large difference in stretchability and friability between the sulfide and the oxide. In particular, the interaction effect of MnS and oxides on the resistance to squeezing is more effective than that of conventional steels, with the effect of steel containing B. Precipitation is promoted by using complex oxides containing Mn and B as nuclei. This is considered to be a characteristic of the prepared MnS.
Next, the steel composition will be described in detail.
Conventionally, it is known that the lower the C, the better the workability. In the present invention, C is 0.010% or less. In order to obtain high elongation and r value, it is desirable to make it 0.0025% or less. A more preferable range is 0.0015% or less. The lower limit is not particularly limited, but lowering the C content increases the steelmaking cost, so 0.0003% or more is desirable.
Si can be contained in a small amount to control the composition of the oxide. To obtain this effect, the content is made 0.001% or more. On the other hand, an excessive content not only tends to inhibit the enamel characteristics, but also forms a large amount of Si oxide having poor ductility in hot rolling, which may reduce the resistance to sticking. 100% or less. Preferably it is 0.030% or less, More preferably, it is 0.015% or less. From the standpoint of improving foam resistance, sunspot resistance, etc. and obtaining better enamel surface properties, the preferred range is 0.008% or less.
Mn is an important component that affects the oxide composition variation in relation to the amounts of oxygen and Nb added. At the same time, it is an element that prevents hot brittleness caused by S during hot rolling. In the present invention containing oxygen, the content is 0.03% or more. Desirably, it is 0.05% or more. In general, enamel adhesion becomes worse and bubbles and black spots are more likely to occur as the amount of Mn increases. However, in the steel of the present invention that makes the best use of Mn as an oxide, these properties deteriorate due to the addition of Mn. Is small. Rather, since the control of the oxide composition is facilitated by an increase in Mn, it is actively added. That is, the upper limit of the amount of Mn is specified as 1.30%. The upper limit is desirably 0.80%, and more preferably the upper limit of Mn is 0.60%.
O is an essential element in the present invention because it directly affects the toughness and workability, and at the same time affects the toughness resistance in relation to the amounts of Mn and Nb. In order to exhibit these effects, 0.005% or more is necessary. Preferably, it is 0.010% or more, more preferably 0.015% or more, and still more preferably 0.020% or more. On the other hand, when the oxygen amount is high, the workability is directly deteriorated due to the high oxygen amount, and the Nb addition amount necessary for the present invention is also increased, resulting in an indirect addition cost increase. Therefore, the upper limit is set to 0.085%. Is desirable. Preferably, it is 0.065% or less, More preferably, it is 0.055% or less.
Al is an oxide-forming element, and it is desirable that oxygen in steel is present as an oxide in the steel material in an appropriate amount in order to improve the toughness as an enamel characteristic. To obtain this effect, 0.0002% or more is contained. On the other hand, Al is a strong deoxidizing element. When it is contained in a large amount, not only is it difficult to keep the amount of oxygen required by the present invention in the steel, but also Al oxidation with poor ductility in hot rolling. There is a case where a large amount of material is formed and the resistance to picking is lowered. Therefore, Al is made 0.030% or less. Preferably it is 0.015% or less, More preferably, it is 0.010% or less, More preferably, it is 0.005% or less.
N is an interstitial solid solution element like C, and when it is contained in a large amount, Nb, and even when a nitride-forming element such as V or B is added, the workability tends to deteriorate and the non-aging steel plate Is difficult to manufacture. For this reason, the upper limit of N is set to 0.0055%. Desirably, it is 0.0045% or less. The lower limit is not particularly limited. However, it is expensive to melt to less than 0.0010% in the current steelmaking technology, so 0.0010% or more is desirable.
When the P content increases, it affects the reaction between glass and steel at the time of enamel firing. In particular, P segregated at a high concentration at the grain boundaries of the steel sheet may deteriorate the appearance of the enamel due to bubbles, black spots, and the like. In the present invention, the P content is 0.035% or less. Preferably it is 0.025% or less, More preferably, it is 0.015% or less, More preferably, it is 0.010% or less.
S forms Mn sulfide and, in particular, has the effect of making the void formation during rolling efficient and improving the resistance to squeezing by making this sulfide complex precipitate on the oxide. It may be 0% which is not contained at all, but 0.002% or more is necessary to obtain this effect. Preferably it is 0.005% or more, More preferably, it is 0.010% or more, More preferably, it is 0.015% or more. However, if the content is too high, the effect of Mn necessary for controlling the composition of the main oxide in the present invention may be lowered, so the upper limit is made 0.080%. Preferably it is 0.060% or less, More preferably, it is 0.040% or less.
B is an essential element in the present invention. B fixes N, improves deep drawability, is non-aging, and is necessary for imparting high workability, and also has an effect of improving adhesion, but in the present invention, it is a special type completely different from this. Included to give an effect. In other words, the added B combines with oxygen in the steel to form an oxide, which works effectively for preventing tripping. In order to obtain this effect, 0.0003% or more is necessary. More preferably, it is 0.0008% or more, More preferably, it is 0.0012% or more, More preferably, it is 0.0015% or more, More preferably, it is 0.0020% or more. However, when the addition amount is high, deoxidation is caused when B is added, and it becomes difficult to keep the oxide in the steel, and the bubble resistance / spot resistance deteriorates, so the upper limit is made 0.0250%. Preferably it is 0.0150% or less, More preferably, it is 0.0080% or less.
Elements having the same effect as B include Nb and V. When Nb is added alone, the effect of improving the r value is remarkable. However, the deterioration of elongation is large and the workability is hindered. However, in the steel according to the present invention containing B essentially, the recrystallization temperature is remarkable. In order to obtain good workability after cold rolling and annealing, annealing at a very high temperature is required, and the productivity of annealing is reduced. For this reason, it is preferable to keep it low, and it should not exceed 0.0040%. More preferably, it is 0.0025% or less, more preferably 0.0015% or less. If it is 0, there is no need to consider the adverse effect of Nb. Further, V is equivalent to Nb in terms of the effect on workability, but the upper limit is wide in consideration of the amount of oxygen remaining in the steel, and recrystallization occurs even when it is added to the B-added steel targeted by the present invention. In addition to being smaller than Nb, the effect of increasing the temperature has the effect of significantly improving the anti-tack property by adding a compound with B to form a composite oxide. In order to obtain the effect of V, 0.003% or more is necessary. Preferably, it is 0.006% or more, more preferably 0.010% or more, and still more preferably 0.015% or more. From the viewpoint of addition cost and foam resistance / spot resistance, the upper limit is made 0.15%. When the content of B is 0.0015% or more and the effect of the invention is obtained with B alone, 0.060% or less, and further 0.040% or less is sufficient.
Cu is contained in order to control the reaction between glass and steel during enamel firing. In a single enamel, Cu segregated on the surface during pretreatment has the effect of promoting microscopic fluctuations in the reaction and improving adhesion. In double enamels, the effect due to surface segregation is small, but it affects the microscopic reaction between laxatives and steel. In order to obtain such an effect, 0.01% or more is added as necessary. Inadvertently excessive addition not only inhibits the reaction between the glass and steel, but also may deteriorate the workability. Therefore, in order to avoid such adverse effects, the content is preferably made 0.500% or less. A preferred range is 0.015 to 0.200%.
Other inevitable impurities may adversely affect material characteristics and enamel characteristics, so it is preferable to make them low. For Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, Mg, the total of one or more is 1.0% or less, preferably 0.5% or less, Preferably, the content is 0.1% or less. If it is contained in a large amount, the reaction with the oxide-forming element cannot be ignored, and the composition and form of the oxide become unfavorable. However, the effect of the present invention is lost even when a larger amount is added. However, it is also possible to positively add an amount larger than this in anticipation of manufacturing or quality advantages other than the advantages assumed by the present invention.
Next, the example of the manufacturing method of the steel plate which concerns on this application is demonstrated. In the present invention, it is necessary to contain B in the oxide, and the technical point of the steel of the present invention is to combine B with O instead of N to control the form of the oxide in the steel. However, there are various ways to achieve that control. For this reason, this application is not limited to the following manufacturing methods.
After adding 80% or more of the total amount of Mn in the melting and casting processes of steel in order to give the characteristic fluctuation of the composite oxide characteristic of the present invention, Mn and B are added to the molten steel. From the viewpoint of productivity, it is advantageous to allow 1 minute or more to elapse, add 80% or more of the total addition amount of B, and perform casting within 60 minutes. In the case of adding V and Nb having the same effect as B, basically, it is preferable to add from an element having a weak deoxidizing ability, and by adding Mn, V, Nb and B in this order, the present invention. The effect of can be obtained more remarkably. Here, the addition is performed by adding 80% or more of the total addition amount of each element and then adding the next element. However, in order to finally adjust the components after the addition of each element, the amount added at less than 10% of the total addition amount is excluded from the consideration of the addition amount here. It is preferable that a time of 1 minute or more elapses when each element is added. More preferably, 2 minutes or more, more preferably 3 minutes or more. Moreover, it shall cast within 60 minutes after adding all the elements. Preferably it is within 40 minutes, more preferably within 20 minutes. Moreover, in the casting process, the effect of the invention becomes more conspicuous by performing the cooling rate at the time of solidification with a ¼ layer thickness of the slab ≦ 10 ° C./second. Preferably it is 5 degrees C / second or less, More preferably, it is 2 degrees C / second or less, More preferably, it is 1 degree C / second or less, More preferably, it is 0.5 degrees C / second or less, More preferably, it is 0.1 degrees C / second or less.
In order to form a composite oxide so that the effects of the present invention can be enjoyed to the fullest extent, it is desirable to add B in the order of Mn, V, Nb, and B as described above. The essence is to effectively form B oxide and combine it with other oxides optimally, and keep the oxygen concentration in molten steel during refining, the concentration ratio of Mn, V, Nb and B and the temperature in a well-balanced manner. If it is possible, the effect of the present invention can be obtained even if Mn, V, Nb, and B are added in a total amount at a time, or any two or more elements are added at once or separately. In the case where Mn, V, Nb, and B are added at a time, or when any two or more elements are added at once or separately, the oxygen concentration in the molten steel is set to 0.010 to 0.070%. It is necessary to adjust to the range, and there is a case where the moderate hit rate / efficiency falls somewhat.
In addition, it is also possible to add a B-type composite oxide having a concentration distribution in advance and then add it to a continuous casting tundish or mold by enclosing it in a wire or the like. This is one of the methods for producing an oxide. The above-mentioned patent documents do not disclose any matters relating to the production of a complex oxide having a large composition variation as defined in the present application, such as the timing of addition of additive elements, solidification conditions, and the like. A sufficient effect cannot be obtained by simply adding B.
That is, in the conventionally known enamel steel plate manufacturing technology, only B is added, and in the conventionally known technology, the formation of B nitride is one of the purposes. In combination with N having a high affinity, B nitride is formed, and B oxide sufficient to function as a hydrogen trap site is not effectively formed.
Furthermore, in the conventionally known enamel steel plate manufacturing technology, since there is no knowledge that an oxide having an effective concentration distribution is important, a technology of adding an oxide having an effective concentration distribution itself after adjustment. There is no existence at all.
For this reason, with the conventionally known enamel steel plate manufacturing technology, it is impossible to form an oxide containing B as defined in the present application and having a large composition variation. Note that nitride is less effective for improving the anti-tack property, which is the object of the present invention, as compared with an oxide.
On the other hand, in the present invention, it is necessary to contain B in the oxide. Therefore, in the present application, for example, Mn oxide is formed by adding Mn first as in the above-described manufacturing method, and thereafter Oxidation with a large composition variation as defined in the present application, in which B is combined with an oxide such as Mn by adding B or by adding an oxide having an effective concentration distribution after adjustment. To form things.
The formation of the optimum complex oxide as described above does not occur only due to the component change or elapsed time due to the addition of elements, and is also strongly related to temperature. In particular, it is important to control the reaction at a high temperature from the end of the addition of elements and oxides to the initial stage of solidification. In particular, when the steel changes from a liquid to a solid, the solubility of various elements in the steel also changes greatly, which has a considerable influence on the composition variation. For this reason, the cooling rate at the time of solidification is important in order to obtain the effects of the invention sufficiently. If it is too early, fine oxides and precipitates are formed apart from the original coarse composite oxide, and the effect of the invention is hindered. On the other hand, if it is too slow, the composition becomes uniform and the effect of the invention is small. Not only will it be less productive. In general, the cooling rate of the steel slab at the time of casting differs depending on the position in the plate thickness direction. Therefore, in the present invention, the cooling rate is typically defined by the cooling rate at the 1/4 layer thickness. The cooling rate in the quarter layer is generally accepted and is determined by heat transfer calculation that is also used in operation control and the like.
The composite oxide targeted by the present invention can obtain the effects of the invention remarkably when the average diameter is 1.0 μm or more at the time of the slab after solidification is completed. Preferably, it is 4.0 μm or more, more preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. The reason why the oxide at the time of completion of casting is preferably coarse is considered to be that if it is fine, the stretchability of the oxide at the time of steel slab processing becomes poor and crushing is difficult to occur. What is specified here is an average diameter, and is usually measured for a complex oxide having a size that can be observed with an optical microscope or a low-power scanning electron microscope.
In a normal steel plate manufacturing process, this composite oxide is stretched and crushed by rolling to change it into a form more preferable for the intended characteristics. For this purpose, a certain amount of processing is required, and it is preferable to set the thickness of the steel piece that has been cast to be 50 mm or more. In the production process, rolling is performed to about 1 to 8 mm by hot rolling and further to about 2 to 0.2 mm by cold rolling, so that the total strain is 3 to 5 or more in logarithmic strain. In addition, in order to obtain better toughness, rolling at a temperature of 600 ° C. or higher is performed at a temperature of 1000 ° C. or higher and a total true strain of 0.4 or higher under the condition of a strain rate of 1 / second or higher. After performing, it is effective to perform rolling at a total sum of true strains of 0.7 or more under conditions of 1000 ° C. or less and a strain rate of 10 / sec or more. This is considered to be because the formation of complex oxides having different compositions in the steel and the accompanying void formation process is controlled, and preferable complex oxide / void morphology and properties are obtained. Although this mechanism is not clear, the mechanism which this invention expresses is demonstrated below. The voids that function as hydrogen trap sites are mainly formed by crushing the complex oxide in the cold rolling process after hot rolling. The shape of the complex oxide must be controlled in the previous hot rolling process. is important. In other words, in the hot rolling process, the complex oxide is softened because of the high temperature, and the hardness difference from the base metal, which is the parent phase, is small. It does not occur and the composite oxide stretches. Further, when the temperature is lower than 1000 ° C. and below about 900 ° C., the composite oxide becomes difficult to be stretched, but remarkable crushing as in the case of cold rolling does not occur, and some cracks that generate micro cracks occur. In order to obtain a composite oxide that has been stretched at the same time and has microcracks before cold rolling, it is deformed because of temperature control during hot rolling, strain in each temperature range, and hot working. In addition, since the recovery of ground iron and complex oxide occurs remarkably, the control of strain rate is important.
If the hot working temperature region is too high, the composite oxide cannot be imparted with strain that causes severe recovery and crack formation. On the other hand, if it is too low, the shape of the composite oxide is not elongated but close to a spherical shape, so that cracks are difficult to occur. It is necessary for the formation of cracks to be moderately stretched and thin. For this purpose, in hot rolling, it is necessary to control and impart stretching of the composite oxide by moderate deformation in a higher temperature range and formation of cracks in a lower temperature range. The form of the composite oxide that forms such cracks becomes more complicated when there is a difference in concentration within the composite oxide and there is a difference in deformability as described above. It becomes possible to form.
The hot rolling heating temperature, the coiling temperature, etc. can be set as usual within the normal operating range. The hot rolling heating temperature may be 1000 ° C. or lower, but if rolling at 1000 ° C. or higher is performed in order to sufficiently obtain the effect of stretching the composite oxide in the hot rolling, the coiling temperature is 1050 to 1300 ° C. Is about 400-800 degreeC.
The cold rolling is preferably performed at a cold rolling rate of 60% or more in order to sufficiently crush the complex oxide and to obtain a steel sheet with good deep drawability. In particular, when deep drawability is required, the cold rolling rate is preferably 75% or more.
Whether the annealing is box annealing or continuous annealing, the characteristics of the present invention are not changed, and the characteristics of the present invention are exhibited as long as the temperature is higher than the recrystallization temperature. In particular, continuous annealing is preferable in order to reveal the features of the present invention that the deep drawability is excellent and the enamel characteristics are good. It can be mainly carried out at 650 to 750 ° C. for box annealing and 700 to 890 ° C. for continuous annealing.
As described above, the steel sheet in which the composition variation of the composite oxide is controlled as in the present invention has a very good anti-slip property even if it is applied not only once but also twice. Also, no enamel or black spot defects occur, and the enamel steel sheet has excellent enamel adhesion. The method of glazing can be applied not only to wet glazes but also to dry and powder enamelling without problems. In addition, the application is not limited in any way, and it exhibits its characteristics in the field of bathtubs, tableware, kitchenware, building materials, home appliance panels, etc., and steel plate enamel as a technical classification.

Continuously cast slabs having various chemical compositions were hot-rolled, cold-rolled and annealed under various production conditions. Subsequently, after 1.0% temper rolling, the enamel characteristics were investigated. The components are shown in Table 1, the oxides to be added are shown in Table 1-2, the production conditions are shown in Table 2, and the investigation results are shown in Table 3. In this example, since the influence of the element addition conditions at the time of steelmaking was examined, a slight difference in the components was generated even in the steel aimed at the same component, but the characteristics were compared as equivalent components. For the components judged to be equivalent, the same alphabetical letters were assigned to the steel codes, and serial numbers were assigned within the same alphabetical letters, and the influence of manufacturing conditions was examined. In the column of rolling process in Table 2, A is the sum of true strains applied at 1000 ° C. or higher and strain rate of 1 / second or higher, and B is true applied at 1000 ° C. or lower and strain rate of 10 / second or higher. Means the sum of distortion. Moreover, in the column of the separate oxide distribution in Table 3, the relative positions of the oxides exhibiting the high concentration / low concentration ratio are A: within an angle ± 5 ° and within a distance of 0.5 μm, B: It means that the A condition is not satisfied, the angle is within ± 10 °, the distance is within 20 μm, and the C: B condition is not satisfied. (Here, the oxide is a composite oxide in which oxides of Fe, Si, Mn, Al, Nb, V, B, etc. are combined and integrated. Any 2 not in contact with another oxide. (Refers to a single composite oxide, which is any single composite oxide that is not separated from the same oxide.)
The enamel was dry-processed by a powder electrostatic coating method, applied with 100 μm of lower glaze and 100 μm of upper glaze, and baked at 850 ° C. for 3 minutes in the atmosphere with a dew point of 60 ° C.
As for the anti-pickling property, a squeezing acceleration test is performed by placing the fired plate in a constant temperature bath at 160 ° C. for 10 hours, and the occurrence of the squeezing is visually observed: A: very excellent, B: excellent: C: slightly excellent , D: Normal, E: AE determined to be problematic in 5 stages, and shown in Table 3 as anti-tackiness.
The surface characteristics of bubbles / spots were determined visually, and A: very excellent, B: excellent: C: slightly superior, D: normal, E: determined in five stages of A to E as problematic, Table 3 Indicated.
Enamel adhesion is usually performed by P.I. E. I. In the adhesion test method (ASTM C313-59), there is no difference in adhesion, so a 2 kg ball head weight is dropped from a height of 1 m, and the enamel peeling state of the deformed part is measured with 169 palpation needles. The area ratio of the peeled portion was evaluated.
As is apparent from the results in Table 3, the steel sheet of the present invention is an enamel steel sheet that is remarkably excellent in enamel characteristics, in particular, the toughness. In particular, the effect of improving the toughness by controlling the concentration difference of the composite oxide by controlling the production method is clear.
That is, as shown in Table 3, the steel sheet satisfying the steel components specified in the present invention has a B / max ratio of B of another oxide (specified in claim 1), a Mn max / min ratio of another oxide ( 2), another oxide distribution (B in claim 8 and Mn in claim 9), and max / min ratio in the same oxide (B in claim 6, Bn in claim 7) The steel plate with the steel number satisfying all the above requirements prescribed in the present invention has the most excellent overall enamel characteristics with respect to adhesiveness of 80 to 100%, foam / spot property, adhesion and anti-sticking property. It was an evaluation.
Further, steel numbers (a2, a5, c4, d5, e2, which satisfy the requirement of the max / min ratio of B of another oxide (as defined in claim 1) and do not satisfy any of the other requirements described above. The steel sheet of h1, k1) has an adhesion of 75 to 85%, and has excellent enamel characteristics (B) or slightly excellent (C) with respect to foam / spot characteristics, adhesion, and anti-tackiness. Although there were some, the overall evaluation was excellent overall, and the intended effect of the present invention was obtained.
On the other hand, the comparative examples (11 to n2) do not satisfy the requirement of the max / min ratio of B of another oxide (specified in claim 1), and the enamel characteristics are satisfied even if other requirements are satisfied. The (foam / spot property, adhesion, and resistance to picking) was inferior, and the intended effect of the present invention was not obtained.
In the “rolling” column, A is the sum of true strains applied at 1000 ° C. or more and a strain rate of 1 / second or more, and B is the sum of true strains applied at 1000 ° C. or less and a strain rate of 10 / second or more. means.
In the column of “Different Oxide Distribution”, the relative position of the oxide exhibiting a high concentration / low concentration ratio is A: within an angle ± 5 ° and within a distance of 0.5 μm, and B: satisfies the A condition. It means that the angle is within ± 10 ° and the distance is within 20 μm, and the C: B condition is not satisfied. (Here, the oxide is a composite oxide in which oxides of Fe, Si, Mn, Al, Nb, V, B, etc. are combined and integrated. Any 2 not in contact with another oxide. (Refers to a single composite oxide, which is any single composite oxide that is not separated from the same oxide.)
In terms of anti-tackiness, A: very excellent, B: excellent: C: slightly superior, D: normal, E: A: E is determined to be problematic.
The surface characteristics of bubbles and black spots were determined visually, and A: very excellent, B: excellent: C: slightly excellent, D: normal, E: A: E, which is problematic, was determined in five stages.

  The enameled steel sheet of the present invention satisfies all of the resistance to sticking, foam resistance / spot resistance, enamel adhesion, and surface characteristics required for enameled steel sheets. In particular, the anti-tack property is remarkably improved, the defective product rate in the enamel product manufacturing process is greatly reduced, and the industrial significance is great.

Claims (15)

C: 0.010% or less in mass%,
Mn: 0.03 to 1.30%,
Si: 0.100% or less,
Al: 0.030% or less,
N: 0.0055% or less,
P: 0.035% or less,
S: 0.08% or less,
O: 0.005 to 0.085%,
B: 0.0003 to 0.0250%
The balance is composed of Fe and inevitable impurities, and the oxides of Fe, Mn, Si, Al, and B with a diameter of 0.10 μm or more in the observation unit field of view of 100 μm × 100 μm in the plate cross section are combined and integrated. There are two non-contacting complex oxides having different B mass concentrations, and the highest B mass concentration (B max%) and the lowest B mass concentration (B min%). The ratio of B max / B min ≧ 1.2 is a steel sheet for continuous cast enamel excellent in toughness resistance. A composite oxide in which oxides of Fe, Mn, Si, Al, and B having a diameter of 0.10 μm or more in an observation unit field of view of 100 μm × 100 μm in a cross section of the plate are combined and integrated is brought into contact with different Mn mass concentrations. Any two composite oxides that are not present exist, and the ratio of the highest Mn mass concentration (Mn max%) to the lowest Mn mass concentration (Mn min%) is Mn max / Mn min ≧ 1.2. The steel sheet for continuous casting enamel having excellent toughness resistance according to claim 1. In addition,
Nb: less than 0.004% ,
V: 0.003-0.15%
The steel plate for continuous cast enamel excellent in toughness resistance according to claim 1 or 2, wherein one or two of them are contained. In addition,
Cu: 0.01 to 0.500%,
Excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of claims 1 to 3, characterized in that it contains. Furthermore, in mass%,
It contains 1.0% or less in total of one or more of Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, and Mg. excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of 4. In the composite oxide in which the oxides of one Fe, Mn, Si, Al, Nb, B, V, and Cr existing in the steel plate are combined and integrated, there is a distribution of B mass concentration and high concentration. The ratio of the B mass concentration (B max%) of the part to the B mass concentration (B min%) of the low concentration part is B max / B min ≧ 1.2. 2. A steel plate for continuous casting enamel having excellent anti-tacking properties according to claim 1 . In the composite oxide in which the oxides of one Fe, Mn, Si, Al, Nb, B, V, and Cr existing in the steel plate are combined and integrated, there is a variation in Mn concentration, and the high concentration part The ratio of the Mn mass concentration (Mn max%) of Mn and the Mn mass concentration (Mn min%) of the low concentration portion is Mn max / Mn min ≧ 1.2. The steel sheet for continuous cast enamel excellent in the tear resistance according to item 1 . More than 1.2 times or 1/1 of the B mass concentration (%) of the composite oxide in which the oxides of Fe, Mn, Si, Al, Nb, B, V, and Cr inside the plate are combined and integrated Another composite oxide with a B mass concentration of 2 times or less is a linear distance between the centers of both composite oxides of 0.10 μm or more and within 20 μm, and a straight line connecting the centers of both oxides is from the rolling direction. at an angle within ± 10 °, excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of claims 1 to 7, characterized in that present. More than 1.2 times or 1/1 of the Mn mass concentration (%) of the composite oxide in which the oxides of Fe, Mn, Si, Al, Nb, B, V, and Cr inside the plate are combined and integrated. A straight line connecting the centers of both composite oxides with another composite oxide having a Mn mass concentration (%) of 2 times or less in a linear distance between the centers of both composite oxides of 0.10 μm or more and within 20 μm there at an angle within ± 10 ° from the rolling direction, there excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of claims 1-8, characterized in that. C: 0.010% or less in mass%,
Mn: 0.03 to 1.3%,
Si: 0.100% or less,
Al: 0.030% or less,
N: 0.0055% or less,
P: 0.035% or less,
S: 0.08% or less,
O: 0.005 to 0.085%,
B: 0.0003 to 0.0250%
And the balance is Fe and inevitable impurities, and in the melting and casting processes of steel, Mn and B are added to molten steel by adding 80% or more of the total amount of Mn by mass%, A method for producing a steel sheet for continuous casting enamel having excellent toughness resistance, characterized by adding at least 80% of the total amount of B added in mass% and casting within 60 minutes. In addition,
Nb: 0.004% less than,
V: 0.003-0.15%
The method for producing a steel sheet for continuous cast enamel having excellent toughness resistance according to claim 10, wherein one or two of them are contained. In addition,
Cu: 0.01 to 0.500%,
The manufacturing method of the steel plate for continuous casting enamel excellent in the tear resistance of Claim 10 or 11 characterized by the above-mentioned. Furthermore, it is characterized by containing not less than 1.0% in total of one or more of Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, Mg in mass%. method for producing excellent continuous casting enameling steel sheet for anti Tsumatobi resistance according to any one of claims 10 to 12. In the casting step, a plate thickness 1/4 layers of the slab, resistance Tsumatobi resistance according to any one of claims 10-13, wherein performing a cooling rate ≦ 10 ° C. / sec during solidification A manufacturing method for steel sheets for continuous casting enamel that excels in high quality. When a steel slab having an average oxide diameter of 1.0 μm or more and a thickness of 50 mm or more is rolled at a temperature of 600 ° C. or higher, the total true strain is obtained under the conditions of 1000 ° C. or higher and a strain rate of 1 / second or higher. The rolling according to claim 10, wherein the rolling is performed at a temperature of 1000 ° C. or less and a total strain of 0.7 or more under the conditions of a strain rate of 10 / second or more. The manufacturing method of the steel plate for continuous casting enamel excellent in the tear resistance of any one of Claims 1 .

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