JP3107932B2 - Method of manufacturing composite high-speed sleeve roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a composite sleeve roll such as H-shaped steel rolling rolls or edger roll sheet hot rolling.

[0002]

2. Description of the Related Art Conventionally, as an outer layer of a composite sleeve roll used for rolling an H-section steel, a cast iron-based material such as an adamite material, a ductile material, and a nickel glen material is generally used, and is mainly manufactured by a centrifugal casting method. ing. Also, recently, as a manufacturing technique of a high-speed tool steel-based composite roll having extremely excellent wear resistance, a powder HIP method, a continuous casting overlaying method, and the like are known, and a work roll for wire rod rolling or sheet rolling is known. Has been proven in such fields. However, these methods are not suitable for manufacturing process and equipment.
It is not suitable for producing a large-sized roll having a very large outer layer thickness, such as a sleeve roll for rolling a shaped steel. That is, the equipment is extremely expensive and costly, which makes it difficult to implement.

[0003]

As a method for producing the large-sized sleeve roll, a horizontal or vertical centrifugal casting method is generally used. However, a high-speed tool steel (hereinafter referred to as high-speed steel) -based material containing several percent of carbide-forming elements such as Cr, Mo, W, and V is GNo. When casting at a rotational speed of about 100, there is a problem that carbide segregation occurs due to a difference in specific gravity of each element. As the inner layer material, a tough ductile material is generally used for sleeve rolls made of cast iron. However, when a ductile material having a C composition exceeding 3% by weight is used for the high-speed sleeve roll, abnormalities occur at the boundary between the inner and outer layers. There is a problem that a tissue is likely to be generated, and the strength near the boundary part is extremely reduced. The present invention has been made in view of the above-described problems of the centrifugal casting method, and has as its object to realize a high-performance and sounder composite high-speed sleeve roll used as an H-section steel roll or an edger roll.

[0004]

[Means for Solving the Problems]

According to the method for producing a composite high-speed sleeve roll of the present invention , C is 1.8 to 3.0% by weight of a chemical component;
Cr is 4.0 to 8.0%, Mo is 2.0 to 8.0%, W
Is 2.0 to 6.0%, V is 4.0 to 10.0%, and the balance is
The outer layer made of a high-speed steel-based (high-speed steel) material, which is substantially Fe , and C in a weight ratio of chemical components of 1.0 to 2.0.
0%, Si 1.0-3.0%, Mn 0.2-1.0
%, Ni is 0.3 to 1.5%, and the balance is substantially Fe.
The inner layer made of molten spheroidal graphite adamite material is GN
o. Are sequentially cast by a vertical centrifugal casting method at a rotation speed of 50 to 80.

[0006]

The chemical composition of the material forming the outer layer is an important item in determining the performance of the roll, and the reason why the chemical component ratio of the high-speed material forming the outer layer is limited as described above will be described below. C is necessary for forming carbide for improving wear resistance. When the amount is less than 1.8%, the amount of the crystallized carbide is small, which is not sufficient in terms of wear resistance. On the other hand, if C exceeds 3%, the amount of carbides becomes too large, the strength and toughness are reduced, and the surface roughening resistance is also reduced in terms of roll quality.

[0007] Cr improves the hardenability of the matrix, forms carbides with C, and increases the hardness. If the amount is less than 4%, the effect is insufficient, and if it exceeds 8%, coarse M ₇ C ₃ -based carbides increase, and the surface roughening resistance decreases.
Mo and W combine with C to form M ₂ C or M
_It forms ₆ C carbides and forms a solid solution in the matrix to improve hardenability and strengthen the matrix, so that it has the function of improving wear resistance and increasing high-temperature hardness. However, since these elements have a higher specific gravity than Fe, the higher the content thereof in the centrifugal casting method, the higher the risk of carbide segregation. Therefore, the upper limit of Mo is set to 8.0%, and the upper limit of W is set to 6.0%.

[0008] V combines with C to form a very high hardness MC-based carbide, which greatly contributes to the abrasion resistance of the roll. If the amount is less than 4%, the effect is insufficient, and if it exceeds 10%, the carbides are difficult to be finely and uniformly distributed, and the surface roughness resistance is reduced. Co is not a carbide-forming element, but is added as needed in a range of 12% or less in order to form a solid solution in the matrix and increase the high-temperature softening resistance of the roll.

The spheroidal graphite adamite material for forming the inner layer is obtained by crystallizing spheroidal graphite in its structure by inoculating a Ca-Si alloy or the like into a low-carbon adamite melt. It is superior in toughness to the ductile material used. In addition, since the C value is low, the risk of carbide segregation occurring at the boundary between the inner and outer layers due to elements such as Cr and V in the outer layer material during casting is small, and it is possible to secure toughness near the boundary where the strength tends to decrease. Become.
In addition, the heat treatment of the roll of the present invention having a high-speed outer layer is performed by quenching at a high temperature of 1000 to 1200 ° C. Therefore, it is more advantageous that the inner layer material is a spheroidal graphite adamite material having a higher melting point than a ductile material. is there.

In the production of composite high-speed sleeves, GN
o. When the casting is performed at a rotational speed in a range of 50 to 80, the molten metal cannot be uniformly pressed against the mold due to insufficient centrifugal force when the casting speed is less than 50 G (GNo. Is 50). If it exceeds 80 G, the alloy element added in a large amount tends to segregate due to the centrifugal action, causing a problem of causing structural abnormalities.
Further, the vertical centrifugal casting method is used because when the horizontal centrifugal casting method is used for casting at 50 to 80 G, a laying phenomenon due to insufficient centrifugal force is likely to occur, and it is difficult to obtain a sound product. In general, 100 to 150 G for horizontal centrifugal casting and 100 to 150 G for vertical centrifugal casting.
It is performed around G. In this vertical centrifugal casting, it is necessary to inject the molten metal forming the outer layer into the mold and then inject the molten metal forming the inner layer at an appropriate timing. This is because if the amount of the outer layer melted by the inner layer molten metal is large, the amount of alloying elements in the outer layer material mixed into the inner layer material is increased, and the toughness is reduced.

[0011] The composite HSS sleeve roll obtained by the production method of the present invention is a roll in which a high-hardness HSS-based outer layer having extremely excellent wear resistance and a spheroidal graphite adamite inner layer having excellent toughness are completely integrated. It has enough strength to withstand high-load rolling such as H-beam rolling or thin-plate rolling,
It is superior to conventional cast iron rolls in abrasion resistance, and can be expected to improve the quality of rolled material in terms of product surface properties, unit consumption of rolls, and rolling efficiency.

[0012]

【Example】

Embodiment 1 FIG. Body diameter 1000 mm, body length 470 mm, inside diameter 5
A vertical roll for rolling an H-section steel having a thickness of 46 mm and an outer layer thickness of 100 mm (all finished dimensions) was manufactured by a vertical centrifugal casting method, and quenching and tempering heat treatment was performed to adjust the surface hardness to HS80. Regarding the roll of Example 1 and the rolls of Examples 2 and 3 described below, and the composite sleeve roll of the conventional nickel grain material as the comparative example 1 and the conventional ductile material as the comparative example 2, Table 1 shows the chemical components, their ratios, and the roll surface hardness.

[0013]

[Table 1]

As a result of the ultrasonic inspection, the roll of Example 1 was confirmed to be a sound composite sleeve roll without any harmful segregation or defects such as burrows in the outer layer, the inner layer, and the boundary. Was done. A test piece was collected from the extra length of the roll and examined for mechanical properties, metal structure, and cross-sectional hardness distribution. The mechanical properties of Example 1 and Comparative Example 1 are shown in Table 2, the microstructures of the outer and inner layers of the roll of Example 1 are shown in FIGS. 1 (a) and 1 (b), and the outer layer (nickel of Comparative Example 1) 2 (a) and 2 (b) show the microstructures of (glen) and the inner layer (ductile), and FIG. 3 shows the microstructure of the outer layer (ductile) of Comparative Example 2. The microstructure of the inner layer (ductile) of Comparative Example 2 is the same as that of FIG. Comparing FIG. 1, FIG. 2, and FIG. 3, it can be seen that the roll of Example 1 is a good roll having a fine structure and no segregation. FIG. 4 shows the hardness distribution of Example 1.

[0015]

[Table 2]

[0016] Example 1 roll, as can be seen from Table ^2, 93.4Kg / mm 2 tensile strength with an outer layer portion, 61.5Kg / mm ² becomes even boundary layer portion, from the sleeve roll of the conventional cast iron material The strength is much better. Also,
As can be seen from FIG. 4, the outer layer hardness is substantially constant irrespective of the distance from the surface, and the roll of Example 1 has a discard diameter (about 8 mm).
It can be expected that the wear resistance does not deteriorate up to 50 mm). According to the test use of the H-section rolling of the roll of Example 1, the average performance of rolling about 50,000 tons of product is about 4000 tons / mm (abrasion of diameter), and cracks harmful to the roll, No troubles such as seizure occurred and the surface properties of the rolled material were good.

Embodiment 2 FIG. Body diameter 780mm, body length 290m
m vertical rolls for H-section steel rolling were manufactured. The chemical composition and ratio of the outer layer material are as shown in Table 1 above. This roll has a surface hardness of H by the same heat treatment as in Example 1.
Adjusted to S85. Further, this roll was confirmed to be a sound composite sleeve roll by ultrasonic flaw inspection, and is under test use for H-section steel rolling.

Embodiment 3 FIG. Body diameter 915mm, body length 650m
m was manufactured. The chemical composition, ratio, and hardness of the outer layer material are as shown in Table 1 above. The sleeve roll of Example 3 was shrink-fitted into an arbor to form an assembling roll, which was subjected to a continuous test for hot rolling of thin sheets for about two months. As a result, the abrasion resistance and surface properties of the roll were good, It was confirmed that there was no occurrence and the accident resistance was good.

[0019]

According to the present invention, can a large complex high speed steel sleeve roll, such as a conventional for H-section steel rolling has been considered difficult in the production technology roll or edger roll sheet rolled in an implementation, complex technologies or processes Without the need for management,
GNo. Is relatively small, such as 50 to 80, so that the equipment is not extremely expensive and a large, high-performance composite high-speed sleeve roll can be provided. This large-sized composite high-speed steel sleeve roll has a completely integrated high-hardness high-speed stainless steel outer layer with excellent wear resistance and a spheroidal graphite adamite inner layer with excellent toughness. It has sufficient strength to withstand high-load rolling, has better wear resistance than conventional cast iron rolls, and improves the quality of rolled material in terms of product surface properties, the basic unit of rolling, and the rolling efficiency.

[Brief description of the drawings]

FIG. 1 (a) is a microstructure photograph showing the metal structure of the outer layer of the roll of Example 1 of the present invention, and FIG. 1 (b) is a microstructure photograph showing the metal structure of the inner layer of the roll of Example 1;

FIG. 2 (a) is a microstructure photograph showing the metal structure of the outer layer of a conventional nickel-grain roll (Comparative Example 1),
(B) is a microstructure photograph showing the metal structure of the inner layer of the conventional roll.

FIG. 3 is a microstructure photograph showing the metal structure of the outer layer of a conventional roll made of a ductile material (Comparative Example 2).

FIG. 4 is a graph showing a hardness distribution of Example 1 of the present invention.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22C 38/00 301 C22C 38/00 301L 302 302E 38/22 38/22 (56) References JP-A-4-176840 (JP, A) JP-A-62-144806 (JP, A) JP-A-2-258949 (JP, A) JP-A-3-23046 (JP, A) JP-A-3-14046 (JP, U) JP-A-4-22164 ( JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) B22D 19/16 B21B 27/00 B21B 27/03 520 B22D 13/00 501 C22C 37/04 C22C 38/00 301 C22C 38 / 00 302 C22C 38/22

Claims (1)

(57) [Claims] C is 1.8 to 3 in weight ratio of chemical components.
0%, Cr is 4.0 to 8.0%, Mo is 2.0 to 8.0.
%, W is 2.0 to 6.0%, V is 4.0 to 10.0%,
C is 1.0 to 2.0% by weight of an outer layer of a high-speed steel-based material having a balance of substantially Fe and a chemical component,
1.0 to 3.0% of Si, 0.2 to 1.0% of Mn, N
i is 0.3 to 1.5% and the balance is substantially Fe . Is 5
A method for producing a composite high-speed sleeve roll, comprising sequentially casting by a vertical centrifugal casting method at a rotation speed of 0 to 80.