JPS6021003B2 - Composite sleeve roll for rolling H-type steel and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite sleeve roll mainly used in the field of rolling H-shaped steel, and relates to a new type of roll having higher performance and a preferable method for manufacturing the same.

When rolling H-shaped steel, it is common to use a universal mill from the standpoint of productivity and quality assurance, but most of the rolls used in this universal mill, namely horizontal rolls, vertical rolls, and edge rolls, are It is a sleeve type. In casting sleeve rolls, the method shown in FIG. 1 is generally adopted from the viewpoint of improving the quality of the material and improving the casting process.

That is, first, the outer shell is cast by centrifugal force, and the inner shell is cast by centrifugal force when it is unsolidified or after solidification is completed, and both are allowed to settle. In this case, since the inner shell material reinforces the roll, particular attention must be paid to the toughness of the rice grain.

On the other hand, since the outer shell material is in contact with the rolled material and is directly linked to rolling performance such as wear resistance and roughness resistance, improving the outer shell material is most important. In particular, in the case of horizontal rolls, sliding wear with the flange of the H-beam steel is severe, and the properties generally required in hot rolling (crack resistance, glazing resistance, roughening resistance, wear resistance)
Of these, wear resistance is particularly important. Further, with regard to vertical rolls and edger rolls, there is a growing demand for improved wear resistance as the number of rolling tones has increased recently. Adamite material with Hs55 to 65 is used as the outer shell material of this type, but it has problems in terms of resistance to scratching and roughness, and it is difficult to manufacture with a hardness of Hs65 or higher. This is difficult due to technical issues and the possibility of accidents during use.

In addition, the welding of the outer shell and inner shell must be sound in order to prevent accidents during use of the rolls, and composite technology is also considered to be an important issue. Against this background of the prior art, the present invention has created a new composite sleeve roll of this type that has superior wear resistance and sufficient accident resistance compared to conventional rolls, and also A suitable manufacturing method is also provided.

That is, the present invention is made by welding and integrating an outer shell made of a high chromium material, an inner shell made of spherical graphite steel, and an intermediate layer interposed between the outer and inner shells, as detailed below. The present invention provides a new composite sleeve roll having an outer shell hardness of Hs 65 to 80, and at the same time provides a manufacturing method thereof using a centrifugal casting method.

The outer shell of the rear sleeve roll for rolling H-type steel of the present invention,
Each material of the intermediate layer and inner shell will be explained in detail below.

First, the outer shell material is made of a high chromium material having a hardness of Hs 65 to 80, and the range of each component and the reasons for the limitations are explained as follows. C should be determined by the desired carbamate group while maintaining a balance with Cr within a range that stabilizes the 7C3 type carbide (Fe-C).2.
If the content is less than 0%, the amount of carbides is small and the wear resistance is insufficient, while if the content exceeds 3.2%, the amount of carbides becomes too large, resulting in significant deterioration in mechanical strength, especially in terms of grade. Therefore, C is defined as 2.0 to 3.2%. Si is necessary for deoxidizing sunlight, and if it is less than 0.5%, it will have no effect, but if it is more than 1.5%, it will cause deterioration of mechanical properties, and it will also cause argon and unpleasant odors. It lowers the point and makes it difficult to obtain hardness. Therefore, the Si content is set in the range of 0.5 to 1.5%. Mn is required to have a content of at least 1.5% as an aid to deoxidizing Si, and if it is less than 0.5%, there is no deoxidizing effect.

However, if the content exceeds 1.5%, there will be significant deterioration in mechanical strength, especially in terms of strength. Therefore, the Mh content is also 0.5
The range is 1.5%. P is an element that is preferably as small as possible especially in the roll material, and is set at 0.1% or less in view of making the material brittle. Like P, S makes the roll material brittle, so the smaller the content, the more desirable it is, and its content should be 0.1% or less.

Ni is included to improve repellency and actively adjust hardness, and if it is less than 0.8%, it has no effect;
．． If the content exceeds 5%, retained austenite increases and hardness increases, which is surprising. Therefore, in the present invention, in order to obtain the target hardness Hs65-80, the Ni content is set at 0.8-80.
The range is 2.5%. Cr is used to improve toughness and wear resistance, but if its content is less than 10%, many M3C type carbides will crystallize, and the toughness and fine uniformity of carbides will not be restricted. When the content exceeds 2.5%, the amount of carbide in the Pond 3C6 type increases. This carbide has lower hardness than the M7C3 type carbide and does not have sufficient wear resistance. In the present invention, the range in which M7C3 type carbides occur is balanced with the specified range of C content.
The r content is defined in the range of 10-25%. Mo is effective in increasing the scaling resistance and at the same time entering the carbide, increasing the hardness of the carbide and promoting the tempering softening resistance, and when the content is 0.5%, this effect is small. Moreover, if the content exceeds 2.0%, residual austenite will become stabilized in the matrix, which will actually cause a decrease in hardness.

Therefore, the Mo content is set in the range of 0.5 to 2.0%.
The outer shell material contains each of the above components in weight percent, with the remainder essentially consisting of Fe, but the following may be added as an auxiliary component and is particularly effective: Examples include Nb and V. Nb is effective in refining the casting structure, and the inclusion of Nb promotes precipitation hardening and improves wear resistance, especially when the target hardness is Hs65~
In the range of 80%, this effect is obtained when the Nq content is 1.0%, and when it exceeds 1.0%, this effect is saturated and the cost increases.

Therefore, the Nb content is set to 1.0% or less. V is Nb
It is contained for the same purpose as the target hardness Hs6.
In the range of 5 to 80, the V content may be less than 1.0%, and 1
．． If the content exceeds 0%, the amount of V carbide increases, resulting in deterioration in rutting properties. Therefore, the V content is set to 1.0% or less. In the above description of the outer shell material, each component has been mainly explained in relation to its target hardness Hs of 65 to 80, and this is based on the following reasons.

In general, rolls for rolling H-type steel are required to have abrasion characteristics between the side wall and the flange of the H-type steel, resistance to side wall surface roughness, crack resistance, and flange breakage, and the wear resistance of the roll has a correlation with hardness. If the hardness is less than Hs65, the roughness resistance and abrasion resistance will decrease rapidly. However, on the other hand, the accident resistance and crack resistance against local heat generation of the roll during abnormal rolling, as well as the resistance against flange breakage against large rolling loads, deteriorate rapidly after hardness reaches HS80. It's across the street. Therefore, in order to ensure excellent roughness resistance, abrasion resistance, accident resistance, and crack resistance,
In the case of high chromium materials, the hardness range of Hs 65 to 80 is thin. Next, the middle layer will be explained.

This intermediate layer is interposed between the outer shell and the inner shell,
Outer shell to inner shell (mari core) mainly made of high chromium material
The purpose of this is to prevent the inner shell material from deteriorating its toughness due to the increase in Cr content due to mixing and diffusion of Cr into the inner shell material. The range of each component of the intermediate layer material and the reason for its limitation will be explained as follows. First, the C content is defined as a molten metal component in the range of 1.0 to 2.0%, and in the state where it is partially mixed with the outer shell after casting, that is, when it is a product, the C content is 1.0% to 2.0%. The range is 3 to 2.5%.

That is, when the intermediate layer molten metal is cast onto the inner surface of an already cast outer shell, a part of the inner surface is melted, and the C content of the intermediate layer material fluctuates (increases).
If Rakuyo is used in the intermediate layer with a C content of 2.0%, the C content will be 1.3 to 2.5% if the amount of dissolved outer shell is completely and uniformly mixed into the intermediate layer. The reason for this restriction is that the setting sun component has CI. When it is below 0%, the temperature of the intermediate layer becomes high and the outer shell becomes easy to melt, further increasing the amount of Cr mixed into the intermediate layer and preventing the diffusion of Cr into the inner shell (shaft core). This is because the reason for the existence of the middle layer is lost, and if C exceeds 2.0%, the amount of carbide increases, and the sardine quality of the middle layer itself deteriorates, which also causes the reason for the existence of the middle layer to be lost. It's for a reason. Si
It has the effect of deoxidizing the molten metal, and 0.2% or more is necessary, but if it exceeds 2.0%, it becomes brittle and deteriorates the mechanical properties of the intermediate layer, so 0.2 to 2.0% is necessary. % range.

Mn also has the same effect as Si, and 0.3% or more is required as MmS to remove the adverse effects of S, but if it exceeds 2.0%, the effect is saturated and the mechanical properties also deteriorate. Since it causes deterioration, the content is set in the range of 0.3 to 2.0%.

Although P increases the fluidity of the molten metal, it lowers the toughness of the material when used in roll materials, so it is limited to 0.1% or less.

Like P, S also makes the roll material brittle, so it should be kept at 0.1% or less without causing any actual damage.

Although Ni is contained in an amount of 0.2% or more due to contamination from the outer shell material even if it is not specifically added, the Ni content of 2.5% does not pose a problem.

However, if it exceeds 2.5%, competitiveness improves, which makes the base too hard, which is undesirable from the viewpoint of sardine character, and also increases residual stress, so it is restricted to 2.5% or less. There is a need to. Regarding the middle-class Rakuyo before Zenikomi, taking into account the amount of contamination from the outer shell, the Ni child was set at 2.
It is necessary to keep it below 0%. As for Cr, it is preferable that it is low because of the significance of casting the intermediate layer, and the content of the Zenigome molten metal is regulated to 1.5% or less, which is easy to control industrially. In other words, when Cr is contained in an amount exceeding 1.5%, the content of the intermediate layer increases when combined with the amount of Cd mixed in from the outer shell after casting, and is eventually mixed into the inner shell (mari core). Cr
In order to prevent this problem, it is necessary to limit the Cr content of the twill component to 1.5% or less. Incidentally, when an intermediate layer molten metal with a Cr content of 1.5% or less is cast, the Cr content after casting is in the range of 0.5 to 9.0%. Mo has the same effect as Ni, but if the content exceeds 1.5%, the intermediate layer becomes too hard, so 1.5% is recommended as a range that does not cause any actual damage.
Limited to:

The intermediate layer material contains each of the above components in weight percent, and basically the remainder is substantially composed of Fe, but other components other than the above, and if necessary, the following Ti, N, Zr as a deoxidizing agent. These can be added singly or in combination. That is, since the intermediate layer material is a material that is relatively easily oxidized, one or more of Ti, N, and Zr is contained in the total weight percent.
By adding less than 0.1% of Ni and deoxidizing it, a material-sounder intermediate layer can be obtained. Regarding the upper limit of the added content, all of the above elements are strong deoxidizing agents, so if they are contained alone or in combination at 0.1% or more, it will become a state of overoxidation, which is undesirable. This is because the material contains oxides as reaction products, which deteriorates the mechanical properties of the material. Next again,
To explain the inner shell material of the roll according to the present invention, this inner shell is made of a so-called spherical graphite steel material, and the range of each component and the reason for limitation are explained as follows.

Regarding the inner shell material, during casting, part of the inner surface of the previous intermediate layer is washed and settled, so it is necessary to take this washing into account when determining the moat composition during casting of the inner shell. In the case of graphite steel, C dissolves into the base and becomes graphite. (In some cases, a portion becomes eutectic cementite.) When the C content is less than 1.0%, melting and casting temperatures become high, resulting in increased costs. On the other hand, if it exceeds 2.0%, the graphite tends to lose its spherical shape, and its toughness deteriorates. Therefore, in order to ensure strength, C is defined as 1.0 to 2.0% (excluding 2.0%). Si has a close relationship with graphite crystallization, and if it is less than 0.6%, it is almost difficult to crystallize graphite. However, if it exceeds 3.0%, Si dissolved in the ferrite tends to deteriorate the toughness of the material. Therefore, the Sj content is 0.6-3.0%
The range shall be . In general, it is known that Si is inoculated with CaSi or the like immediately before making a payment to promote graphitization, and this technology is applied in the production of the present invention. CaSj can be added in an amount of 0.1 to 1.0% as Si content just before the addition.
In this case, if the content is 0.1%, the effect of graphitization is small, while if it exceeds 1.0%, the effect is saturated and it is not economical. Even when inoculated, the above Si component range is Ca
It is regulated by the content after addition of Si, etc. Mn combines with S and acts as MhS to remove the negative effects of S, but 0.2
If the content is less than 1.0%, the effect cannot be obtained, while if it exceeds 1.0%, the toughness of the material will deteriorate significantly, so the content should be reduced to 0.
．． The range is 2% to 1.0%.

P increases the fluidity of the falling sun, but since it makes the material brittle, it is preferably as low as possible, and is set at 0.1% or less.

Like P, S makes the material brittle, so the lower the content, the better, and should be 0.1% or less. Note that when CaSi is added, S is generally desulfurized by Ca.
O. It will be 0.4% or less. Ni is effective in delaying the transformation of the material and forming strong ruts, but 0.1% or more and 1.0% or less is necessary and sufficient.

If it is less than 0.1%, the above effect will be insufficient, but since roll gun is generally used as the raw material for melting, it will not be good for aesthetics.
It is difficult to obtain a material containing less than 0.1% i. Cr
Since the outer shell is made of a high chromium material, it is unavoidable that a certain amount of Cr will be mixed into the inner shell as the outer and inner shells are welded together, and care must be taken especially when determining the inner shell hot water composition.

This varies depending on the outer shell component, inner shell component, and casting conditions, but the Cr content of the inner shell material is 0.2 to 1
．． Increase by 0%. The Cr content of the inner shell as a product is 0.
A range of 3 to 2.0% is suitable. In other words, Cr is effective in making the material more rutting, but if it is less than 0.3%, it has no effect, and if it exceeds 2.0%, graphite crystallizes and becomes noisy, so it actually deteriorates the rutting property. It is for the sake of coming.
On the other hand, in order to regulate the Cr content of the inner shell material within a predetermined range, it is necessary to take into account the Cr content from the outer shell and adjust the Cr content of the inner shell molten metal at the time of casting. 0
．． It is necessary to specify it within the range of 1 to 1.0%. Mo is N
Like i, it is an important element in terms of ensuring strength, but 0.
If it is less than 1%, it has no effect, and if it exceeds 1.0%, it becomes hard and brittle, so the Mo content should be 0.1%.
-1.0% range.

The inner shell material contains the above-mentioned components in each weight%, and the remainder is basically composed of Fe, but other components other than those mentioned above, and if necessary, the following Tj, AI, Zr as deoxidizers. These can be added singly or in combination. That is, since the C content of the inner shell material is within the range of 1.0 to 2.0%, one or more of Ti, Zr, and Zr are added in an amount less than 0.1% by total weight. By deoxidizing,
This results in a roll that is materially sounder and free of cavities. Regarding the upper limit of the added content, all of the above elements are strong deoxidizers, so if they are contained alone or in combination at 0.1% or more, the molten metal will become overoxidized, and This is to reduce the fluidity of the molten metal. The composite sleeve roll for rolling H-shaped steel according to the present invention has the above-described configuration, and a method for manufacturing this roll by centrifugal casting will be explained with reference to the example shown in FIG.

That is, on the rotating rollers 6, 6 of the Liaoxin force casting machine, sleeves 2, 2 made of sand molds or heat-resistant bricks are placed at both ends of the inner surface.
The rotary mold 1 in which is fixed is reinstalled, and while the mold 1 is rotating, the outer shell 3 is first inserted from the moat ladle 7 through the Zenigome Shigeru 8 and the like.
Then, while the inner surface of the outer shell 3 is partially or completely unsolidified, the molten metal to form the intermediate layer 4 is poured, and further, after it has solidified or while it is still unsolidified, the molten metal that is to form the intermediate layer 4 is poured. The molten metal that is to form the shell 5 is poured.

In this way, these three members, ie, the outer shell 3, the intermediate layer 4, and the inner shell 5, are completely combined metallically to form an integral roll. Note that although the illustrated casting method is exemplified in which the rotating shaft is horizontal, this does not, of course, preclude casting with the rotating shaft changed to an inclined state.

Also, when casting the inner shell 4, place the fin-containing side of the inner shell 4 into the outer shell 3.
Unlike the case of , it is possible to cast from the opposite side, which is effective in ensuring a uniform outer shell thickness. Next, an example of a composite three roll for rolling H-shaped steel according to the present invention will be described.

Example C: 2.21%, Si: 0.62%, Mn: 0.78%
, P: 0.012%, S: 0.009%, Ni: 1.0
2%, Cr: 12.1%, Mo: 0.28%, the remainder substantially consisting of Fe, C: 1.60%, Si:
0.48%, Mn: 0.52%, P: 0.018%, S
:0.012%, Ni:0.23%, Cr:0.18%
, Mo: 0.21%, the balance substantially consisting of Fe, C: 1.48%, Si: 1.72% (CaSi
(Si content: 0.6% inoculation), Mn: 0. Total %, P:
0.042%, S: 0.021%, Ni: 0.26%,
Cr:0. Spot %, Mo: 0.20%, remainder substantially Fe
Using the inner shell Rakuyo, which was made of 300 ml of aluminum, the three parts were melted into one piece by centrifugal casting using the method shown in Figure 1.

However, the manufacturing conditions are as follows. Mold inner capacity: 870
0 Casting wall thickness (one side): Outer shell, low side, inner shell, 9 sides, middle layer, 3 places.Heat treatment: 600qo x 2 plate R distortion removal key.A roll of 8300 x 350 (inner diameter 5000) was extracted from this material.
When the surface hardness was measured, Hs was 65 to 67, and the chemical composition analysis results of the imitation 20 m from the roll surface were as follows.

C: 1.56%, Si: 1.61%, Mn: 0.42%
, P: 0.038%, S: 0.018%, Ni: 0.2
5%, Cr: 0.48%, Mo: 0.20%, Ti: 0
．． 028%, residual Fe, and the chemical component analysis results at a position 90 ships from the roll surface showed the following obstruction. C:1
．． 82%, Si: 0.57%, Mn: 0.62%, P:
0.016%, S: 0.010%, Ni: 0. Dislike%, c
r: 4.02%, Mo: 0.25%, residual Fe The present invention is as explained in detail below, and in the composite sleeve roll for rolling H-shaped steel according to the present invention, the outer shell is The inner shell is made of spherical graphite steel material with a specific chemical composition, and an intermediate layer with a specific chemical composition is interposed between the outer and inner shells to prevent Cr from being mixed into the inner shell. Since these are integrated by welding, the outer shell contains a large amount of (Fe-Cr)7C3 type carbide, ensuring that the target outer shell hardness of Hs 65 to 80 is achieved. As a result, it has excellent wear resistance and significantly contributes to the reduction of uneven wear during actual rolling.On the other hand, the inner shell has a tensile strength of 40k9/Iso or higher, which makes it a strong material, and is superior to conventional materials. Compared to ductile cast iron, which had a smaller amount of graphite, it has superior competitiveness, and the presence of an intermediate layer reliably solves the problem of material deterioration due to contamination from the outer shell, making it more resistant to breakage accidents. Due to the synergistic effect of these excellent properties of the outer and inner shells, this roll has a remarkable improvement effect on rolling performance and roll life compared to conventional products, and is extremely effective especially in the field of H-shaped steel rolling. It can be useful.

In addition, according to the manufacturing method of the present invention by Liaoxin force casting, the intermediate layer and inner shell are formed by centrifugal force casting following the outer shell, so there is little mixing between each layer, and in particular, the Cr of the inner shell molten metal is formed by centrifugal force casting. The content is regulated to a low level in consideration of the amount of contamination from the outer shell, so that the inner shell material does not become high in Cr due to the presence of the intermediate layer, and the hardness does not deteriorate. Good results were obtained in terms of weldability, and the method is particularly useful as a technical means for obtaining the desired composite sleeve roll.

In addition, in the roll according to the present invention, since the C content of the inner shell is lower than that of the outer shell, if the intermediate layer is not provided, the final solidified part will be inside the outer shell, so the welded part will be pulled toward the outside. Although there is a high possibility that nested defects will occur, the interposition of the intermediate layer has the advantage of reliably eliminating this defect. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing one example of the manufacturing method according to the present invention.

Figure 1

Claims (1)

[Claims] 1 C: 2.0 to 3.2% P: 0.1% or less Cr:
10~25% Si: 0.5~1.5% S: 0.1%
Below Mo: 0.5-2.0% Mn: 0.5-1.5
%Ni: 0.8 to 2.5% by weight, and an outer shell made of a high chromium material consisting essentially of Fe; C: 1.3
~2.5% P: 0.1% or less Cr: 0.5-9.0
%Si: 0.2-2.0% S: 0.1% or less Mo
: 1.5% or less Mn: 0.3 to 2.0% Ni: 0.
and an intermediate layer containing 2 to 2.5% by weight with the remainder substantially consisting of Fe; C: 1.0 to 2.0% (excluding 2.0%) Si: 0.6 to 3 .0% P: 0.1% or less Ni:
0.1-1.0% Mn: 0.2-1.0% S: 0.
1% or less Cr: 0.3-2.0% Mo: 0.1-1.
The inner shell is made of spheroidal graphite steel material containing 0% by weight and the remainder is substantially Fe, and the outer shell has a hardness of HS65 to HS65. 8
1. A composite sleeve roll for rolling H-type steel, characterized in that it has a roll of 0. 2. The roll according to claim 1, wherein the outer shell material further contains 1.0% or less Nb and 1.0% or less V by weight. 3. The roll according to claim 1, wherein the intermediate layer material further contains one or more of Ti, Al, and Zr in a total weight percent of less than 0.1%. 4. The roll according to claim 1, wherein the inner shell material further contains one or more of Ti, Al, and Zr in a total weight percent of less than 0.1%. 5 By centrifugal force casting method, C: 2.0 to 3.2% P: 0.1% or less Cr: 1.
0-2.5% Si: 0.5-1.5% S: 0.1%
Below Mo: 0.5-2.0% Mn: 0.5-1.5
After casting a molten high-chromium outer shell containing 0.8 to 2.5% Ni and the remainder substantially Fe, while the inner surface is partially or completely unsolidified, C: 1.0
~2.0% P: 0.1% or less Cr: 1.5% or less
Si: 0.2-2.0% S: 0.1% or less Mo: 1
．． 5% or less Mn: 0.3-2.0% Ni: 2.0%
C: 1.0 to 2.0% (2.0% is not included). ) Si: 0.6-30% P: 0.1% or less Ni: 0
．． 1-1.0% Mn: 0.2-2.0% S: 0.1
% or less Cr: 0.1-1.0% Mo: 0.1-1.0
A molten inner shell made of spheroidal graphite steel containing % by weight and the remainder substantially consisting of Fe is cast, and an outer shell, an intermediate layer and an inner shell are formed.
A method for manufacturing a composite sleeve roll for rolling H-shaped steel, which is characterized by preventing the occurrence of nest-like defects and welding and integrating. 6. The method for manufacturing a roll according to claim 5, wherein the outer shell molten metal further contains 1.0% or less Nb and 1.0% or less V by weight. 7 In addition, one or two of Ti, Al, and Zr are added to the intermediate layer molten metal.
6. The method for manufacturing a roll according to claim 5, wherein a total amount of less than 0.1% by weight of at least one species is added for deoxidation. 8. The method for manufacturing a roll according to claim 5, wherein one or more of Ti, Al, and Zr is further added to the inner shell molten metal in a total weight percent of less than 0.1% to deoxidize the inner shell molten metal.