JP3258154B2 - Method for producing continuous casting roll and continuous casting roll produced by the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a continuous casting roll and a continuous casting roll produced by the method.

[0002]

2. Description of the Related Art As a continuous casting roll frequently used in continuous casting equipment, a composite roll formed by weld overlaying is the most common. In addition, a molten metal of a desired material is formed around a base material using electromagnetic induction heating. Injection, welding and solidification to form a build-up layer on the outer periphery of the base material (hereinafter referred to as continuous injection cladding method). Have been. The build-up layers, which are the layers used, are mainly made of a martensitic material containing 11 to 16% of Cr and 1 to 4% of Ni. Next, paying attention to the wear phenomenon that governs the life of the roll, the roll repeatedly contacts the high-temperature slab coming out of the mold, so that wear and heat-crack-induced wear are major life-limiting factors. That is,
Abrasion is dominant in the upstream zone, including the top zone, and heat cracks are dominant in the downstream zone. Therefore, in order to improve the roll life, wear resistance,
High heat crack resistance is required, and a material having high strength, high hardness, high toughness, and high ductility is desirable. However, in the build-up layer by the welding build-up method and the continuous injection cladding method, by appropriately combining the chemical composition and heat treatment, high hardness characteristics can be obtained, but since the build-up layer has a solidified structure. There are inherent limitations in obtaining high strength, high toughness, and high ductility. Although a sleeve shrink-fit type roll was also used as a composite roll, there is a problem that the sleeve sometimes swells in addition to the above-mentioned wear phenomenon, and it is hardly used at present. In addition, about how to use the roll, the surface layer where abrasion, heat crack, etc. occurred
At present, the roll is discarded when the depth of the cracks becomes about 20 mm, for example, in which the roll is hardly used repeatedly. One of the reasons for re-cutting and not using repeatedly is that in order to re-cut and use repeatedly, it is necessary that the overlay layer of the martensitic material used is thick, but the most common The build-up method is not suitable for obtaining a thick build-up layer, and in order to make the build-up layer thick, multi-layer build-up welding with an extremely large number of layers is required, which increases the welding cost and is not economical. Another reason is that cracks are shallow for reshaping and repeated use, in other words, heat crack resistance is large and even if cracks occur, it is necessary for the growth rate to be slow. This is because when the cracks become deeper in a relatively short period of time, such as a pile roll, the cracks remain even if the rework is performed, and the rework is meaningless.

[0003]

The problem to be solved is that, in the conventional continuous casting roll by the welding overlay method, the overlay layer used is thin, and the overlay layer has low ductility and low toughness. Heat cracks easily advance and retreat, and are not suitable for remodeling and repeated use. In addition, even if the roll for continuous casting by the continuous injection cladding method can make the build-up layer thick,
It is insufficient in ductility and toughness, so that heat cracks are apt to advance and retreat, and it is not suitable for remodeling and repeated use.
The present invention has been made in view of the above circumstances, and provides a method for producing a continuous casting roll which is excellent in strength and toughness, has a thick build-up layer, and can be used repeatedly, and a continuous casting roll produced by the method. With the goal.

[0004]

According to the present invention, there is provided a semiconductor device comprising:
The method for producing a continuous casting roll described in the above is a method in which a solid base material is placed in a combination mold in which a mold containing a cooling mold is integrally arranged below a refractory heating mold surrounded by an electromagnetic induction heating coil. Is vertically inserted, a separately prepared molten metal of a desired material is injected into a gap between the base material and the combination mold, and the base material is intermittently lowered to melt the molten metal on the outer surface of the base material. The composite material, which is solidified by cooling to form a build-up layer on the outer periphery of the base material, is formed by hot forging. Further, the continuous casting roll according to claim 2 is a continuous casting roll manufactured by the manufacturing method according to claim 1, wherein the build-up layer has a weight ratio of:
C: 0.1 to 1.2%, Si: 0.1 to 1%, Mn:
0.2 to 2%, Cr: 8 to 18%, Ni: 0.2 to 6
%, Mo: 0 to 6%, with the balance being Fe and unavoidable impurities. A continuous casting roll according to a third aspect of the present invention is the continuous casting roll manufactured by the method for producing a continuous casting roll according to the first aspect, wherein the buildup layer has a weight ratio of C: 0.1 to 0.1. 1.2%, S
i: 0.1-1%, Mn: 0.2-2%, Cr: 8-1
8%, Ni: 0.2 to 6%, Mo: 0 to 6%, and one or two of V: 0.1 to 2%, W: 0.5 to 2%, The balance is composed of Fe and inevitable impurities.

[0005]

In the method for producing a continuous casting roll according to the first aspect, a molten metal of a desired material is injected around the base material by using electromagnetic induction heating, and the molten metal is welded and solidified to form a metal on the outer periphery of the base material. Since the buildup layer is formed to make a composite material, there is virtually no restriction on thickening the buildup layer, and it is extremely easy to obtain a thick buildup layer as compared to the buildup welding method. it can. Since the overlay of the composite material obtained by the above method has the same solidification structure as the overlay by the weld overlay method, it can be made to have high hardness by heat treatment, but the solidification structure is destroyed only by heat treatment. In terms of ductility, toughness, and strength, the inherent performance of the chemical composition cannot be sufficiently exhibited. However, by subjecting the composite material to hot forging and plastic working, the solidified structure is destroyed, the structure is densified, and the ductility, toughness, and strength can be significantly improved. Thus, a continuous casting roll having a thicker build-up, higher ductility and toughness, and excellent heat crack resistance compared to the most common conventional continuous casting roll by the overlay welding method is obtained. Next, in the roll for continuous casting according to the second and third aspects, the reason for limiting the chemical composition of the build-up layer is as follows. 0.1% by weight of C
Reason for limiting to -1.2%: C is the most basic element for obtaining a martensite composition by quenching.
If it is less than 1%, it is difficult to obtain martensite of high hardness, so 0.1% was made the lower limit. Further, the higher the C content, the higher the hardness of the martensite structure can be obtained. However, if the content exceeds 1.2%, the effect is small and the toughness is reduced. 8 to 1 by weight of Cr
Reasons for limiting the content to 8%: Cr is the most important element for enhancing the self-hardening property, but if it is less than 8%, sufficient self-hardening property cannot be obtained, and a high Cr content is desirable from the viewpoint of high-temperature corrosion resistance. Therefore, the lower limit was set to 8%. Self-hardening is 10 to 12% Cr
When the Cr content further increases, the self-hardening property decreases and ferrite easily appears.
%, The upper limit is set to 18% because sufficient hardness cannot be obtained even when combined with other elements. Si in a weight ratio of 0.1 to
Reason for limiting to 1%: Si is necessary as a deoxidizing agent and is 0.1
If it is less than 0.1%, the effect is insufficient, so 0.1% was made the lower limit. Even if it exceeds 1%, there is no further effect as a deoxidizing agent, and the toughness is reduced. Therefore, the upper limit is set to 1%. Reason for limiting Mn to 0.2 to 2% by weight: Mn is required as a deoxidizing agent, and S mixed as an impurity is MnS, which is necessary to reduce the influence of S. If the value is less than 0.3%, the effect is insufficient. Therefore, the lower limit is set to 0.2%.
Even if n is increased to exceed 2%, no further effect can be obtained, so the upper limit is set to 2%. Ni is 0.2 to 6 by weight.
%: Ni is necessary for enhancing the curability, stably forming a martensitic structure, and obtaining high hardness.
If it is less than 0.2%, the effect is insufficient, so the lower limit was made 0.2%. Ni is an austenite-forming element. When the Ni content exceeds 6%, retained austenite appears, and high hardness cannot be obtained, so the upper limit is 6%. Reason for limiting Mo to 0 to 6% by weight: The lower limit was set to 0 because a roll that can be used sufficiently without containing Mo can be obtained. However, since Mo increases the tempering softening resistance and the high-temperature strength, it is preferable that the build-up layer of the roll used at a high temperature contains Mo. On the other hand, Mo is a ferrite-forming element. If it exceeds 6%, ferrite appears and sufficient hardness cannot be obtained, so the upper limit is 6%.
%. By making the martensitic material of the above chemical component composition into a build-up layer, a high hardness, high strength, ductility, and good toughness continuous casting roll can be obtained, but when V and W are further added, Further, a build-up layer having excellent wear resistance and high-temperature strength can be obtained. The reasons for limiting the chemical composition of V and W in the continuous casting roll according to the third aspect are as follows. V in a weight ratio of 0.
Reason for limiting to 1 to 2%: V is a strong carbide-forming element, and abrasion resistance is improved by uniformly and finely distributing carbides. If it is less than 0.1%, the effect is insufficient, so 0.1% was made the lower limit. On the other hand, if V exceeds 2%, the toughness decreases, so the upper limit is 2%. W is 0.5 by weight
Reason for limiting to ~ 2%: W enhances high temperature strength,
It is a strong carbide-forming element, and abrasion resistance is improved by uniformly and finely distributing carbides. If it is less than 0.5%, the effect is insufficient, so 0.5% was made the lower limit. On the other hand, if it exceeds 2%, the effect is too thin and the toughness is reduced.

[0006]

EXAMPLES Next, examples embodying the present invention will be described to provide an understanding of the present invention. Here, FIG. 1 is a schematic sectional view of an apparatus used in one embodiment of the present invention, and FIG. 2 is a front view of a test piece of a heat check test for evaluating heat crack resistance. First, as shown in FIG. 1, a graphite buffer type 3 having an inner hole coaxial with the heating type 2 is disposed below a refractory heating type 2 surrounded by an electromagnetic induction heating coil 1. A combined mold A is formed by integrally stacking a coaxial hollow cooling mold 4 at a lower portion. When this apparatus is used, the solid base material 5 is vertically inserted into the combination mold A. Then, a separately prepared melt 6 of the overlay material serving as an outer layer is injected into the gap 7 between the base material 5 and the combination mold A, and the base material 5 is intermittently lowered. Then, while the molten metal 6 is welded to the surface of the base material 5, the graphite-based buffer mold 3 and the hollow cooling mold 4 sequentially cool and solidify the molten metal 6 to form the build-up layer 8. In this case, a silicate glass film 9 is formed on the outer periphery of the base material 5 in advance,
The preheating electromagnetic induction heating coil 10 disposed on the mold A is disposed, and the preheating electromagnetic induction heating coil 1 is disposed.
At 0, the base material is preheated and the silicate glass film 9 is melted and fired, so that the cladding layer 8 can be formed while keeping the base material surface clean. Hereinafter, the embodiment of the present invention will be described in more detail in comparison with a conventional example.

EXAMPLE 1 Using an apparatus as shown in FIG. 1, an S35C material was used as a base material 5, and a molten metal 6 to be a build-up layer was composed of chemical components indicated by symbols A and AC in Table 1 by weight ratio. And the balance Fe
And a continuous injection cladding method in which a build-up layer 8 is formed on the outer periphery of the base material 5 using steel made of unavoidable impurities.
A solid composite of 00 × 2500 mm is manufactured. And
The solid composite material was cut into a length of 300 mm and a length of 2200 mm, and those having a length of 2200 mm were hot forged at a forging ratio of 1.5. After forging, annealing at 870 ℃ × 8h, machining after leaving the finishing allowance, then 950 ℃
And then tempered. Tempering was performed at a higher temperature of 600 ° C., with particular emphasis on ductility and toughness.
After that, finish machining was performed to complete a continuous casting roll having a body diameter of φ300. A 300 mm long conventional sample roll having a length of 300 mm for comparison was manufactured by performing exactly the same heat treatment as that of the forged continuous casting roll without performing forging.

[0008]

[Table 1]

[0009] Table 2 shows the tensile properties of the cladding layer produced by the method of the present invention (continuous injection cladding method + forging) and the conventional method (continuous injection cladding method without forging) thus produced. , Hardness and impact properties. In Table 2, the most common conventional method is the welding overlaying method, and the symbols A and A, which are separately manufactured and have the same outer diameter and the chemical composition indicated by the symbol AW in Table 1 and the balance being Fe and inevitable impurities. The mechanical properties of the overlay having almost the same chemical composition as the composition of the molten metal indicated by AC were also shown. Table 2 shows that the characteristics of the build-up layer obtained by adding the forging to the continuous injection clad method according to the present invention are harder than those of the conventional continuous injection clad method and the build-up layer formed by welding. It can be seen that the proof stress, the tensile strength, the elongation, and the drawing were remarkably improved, although the hardness was almost equal.

[0010]

[Table 2]

Table 3 shows the results of a heat check test performed using the test piece as shown in FIG. 2, in which the material was rapidly heated from 100 ° C. to 650 ° C., and then heated from 650 ° C. to 100 ° C.
The operation of quenching was repeated for 3 minutes in a cycle, and the number of repetitions until cracking occurred was shown. From Table 2, it can be seen that the build-up layer of the present invention having high ductility and toughness has remarkably excellent heat crack resistance as compared with the build-up layer of the conventional method.
In FIG. 2, reference numeral 11 denotes a thermocouple mounting hole.

[0012]

[Table 3]

Example 2 Using the apparatus shown in FIG. 1, S35C was used as the base material 5,
As shown in the chemical composition of Table 4, the molten metal 6 to be the build-up layer 8 forms the build-up layer 8 on the outer periphery of the base material for each of the two types of steel indicated by the symbols B, BC, C, and CC. At least, a solid composite material of φ430 × 2700 mm is manufactured.
And, the solid composite material is 300 mm long and 2400 mm long.
It was cut into lengths and hot forged at a forging ratio of 1.5 for those with a length of 2400 mm. After forging, annealing at 760 ° C x 8h, machining after leaving the finishing allowance,
Normalization was performed at 1050 ° C., and further tempering was performed. Tempering was performed at a lower temperature of 550 ° C. with emphasis on strength and hardness. After that, finish machining was performed to obtain a continuous casting roll having a body diameter of φ320. The 300 mm length was not forged, but was subjected to exactly the same heat treatment as the forged continuous casting roll.

[0014]

[Table 4]

[0015] Table 5 shows the tensile properties and hardness of the cladding layers of the present invention (continuous injection cladding method + forging) and the conventional method (continuous injection cladding method without forging) thus produced. Indicated. As shown by the symbol BW in Table 4, the symbol B
And a continuous casting roll having a build-up layer having substantially the same chemical composition as BC and having the same outer shape was separately manufactured by a welding build-up method, and subjected to exactly the same heat treatment as the symbols B and BC. Table 5 also shows the tensile properties and hardness of the build-up layer by the welding build-up method. Table 5
Although the hardfacing layer according to the method of the present invention and the hardfacing layer according to the conventional method have extremely high hardness, and even though they are at the same level,
The strength and ductility of the build-up layer according to the method of the present invention are significantly improved. That is, it is understood that the forging significantly improves strength and ductility. Table 6 shows the results of the same heat check test as in Example 1. It can be seen that the build-up layer according to the method of the present invention has significantly improved heat crack resistance.

[0016]

[Table 5]

[0017]

[Table 6]

[0018]

As described above, the method for producing a continuous casting roll according to any one of claims 1 to 3 and the continuous casting roll produced by the method have excellent strength and toughness as compared with the conventional method. It is possible to provide a continuous casting roll which has a thick build-up layer and can be re-cut and used repeatedly. In addition, since a composite material having a thick build-up layer can be easily produced by an apparatus using a combination mold having an electromagnetic induction heating coil, production of a continuous casting roll excellent in strength and toughness is extremely economical. Since the manufactured continuous casting roll can be recut and used repeatedly, the life of the continuous casting roll until it is discarded can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an apparatus used in the present invention.

FIG. 2 is a diagram showing a shape of a test piece in a heat check test for evaluating heat crack resistance.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electromagnetic induction heating coil 2 refractory heating type 3 graphite buffer type 4 hollow cooling type 5 base material 6 molten metal 7 void 8 cladding layer 9 silicate glass film 10 electromagnetic induction heating coil for preheating 11 thermocouple mounting hole A Combination mold

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenichi Ozaki 4-31 Makiyama Shinmachi, Tobata-ku, Kitakyushu-shi, Fukuoka Fujiko Co., Ltd. Kitakyushu Factory (56) References JP-A-5-220544 (JP, A) JP-A-5-123854 (JP, A) JP-A-3-254354 (JP, A) JP-A-6-210434 (JP, A) JP-A-53-65214 (JP, A) JP-A-61-194151 (JP, A) JP-A-62-244559 (JP, A) JP-A-62-130758 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/00 B22D 19/16 B22D 19/00 B22D 23/04 B21K 1/00 B21K 5/00 C22C 38/00 302 C22C 38/46

Claims (3)

(57) [Claims] 1. A solid base material is vertically inserted into a combined mold in which a mold having a built-in cooling mold is integrally arranged below a refractory heating mold surrounded by an electromagnetic induction heating coil. Into the gap between the base material and the combination mold, a molten metal of a desired material prepared separately is poured, the base material is intermittently lowered, and while the molten metal is welded to the outer surface of the base material, solidified by cooling. A method for producing a continuous casting roll that can be repeatedly reworked and used, comprising hot forging a composite material having a build-up layer formed on the outer periphery of a base material. 2. The continuous casting roll manufactured by the manufacturing method according to claim 1, wherein the build-up layer has a weight ratio of C: 0.1 to 1.2% and Si: 0.1 to 1%. , M
n: 0.2 to 2%, Cr: 8 to 18%, Ni: 0.2 to
A roll for continuous casting, comprising 6% and Mo: 0 to 6%, with the balance being Fe and unavoidable impurities. 3. The continuous casting roll manufactured by the manufacturing method according to claim 1, wherein the build-up layer has a weight ratio of C: 0.1 to 1.2% and Si: 0.1 to 1%. , M
n: 0.2 to 2%, Cr: 8 to 18%, Ni: 0.2 to
6%, Mo: 0 to 6%, and V: 0.1 to 2
%, W: a roll for continuous casting, containing one or two kinds of 0.5 to 2%, the balance being Fe and unavoidable impurities.