JPH06145887A - Composite high-speed steel sleeve roll and its production - Google Patents

Abstract

PURPOSE:To realize a sounder composite high-speed steel sleeve roll of good performance used as a roll for rolling H-shape steel, an edger roll or the like. CONSTITUTION:This roll is formed of the external layer of a high speed steel series material having chemical components of, by weight, 1.8 to 3.0% C, 4.0 to 8.0% Cr, 2.0 to 8.0% Mo, 2.0 to 6.0% W, 4.0 to 10.0% V and <=12.0% Co, and the balance substantial Fe and the internal layer of a spheroidal graphite adamite material having chemical components of 1.0 to 2.0% C, 1.0 to 3.0% Si, 0.2 to 1.0% Mn and 0.3 to 1.5% Ni, and the balance substantial Fe. The external layer by the molten metal of the high speed steel series material and the internal layer by the molten metal of the spheroidal graphite adamite material are successively cast by a vertical centrifugal casting method at a rotating speed of 50 to 80 in GNo., by which the composite high-speed steel sleeve roll can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite sleeve roll such as a roll for H-section steel rolling or an edger roll for hot rolling a thin plate, and a method for producing the same.

[0002]

2. Description of the Related Art As an outer layer of a composite sleeve roll used for rolling H-shaped steel and the like, cast iron-based materials such as conventional adamite material, ductile material and nickel grain material are generally used, and are mainly manufactured by centrifugal casting. ing. Further, recently, powder HIP method, continuous casting surfacing method, etc. are known as a manufacturing technology of a high speed tool steel composite roll having extremely excellent wear resistance, and work rolls for wire rod rolling or thin plate rolling. Has a track record in fields such as. However, in terms of manufacturing process and equipment, these methods are
It is not suitable for manufacturing a large roll having a large outer layer thickness such as a sleeve roll for rolling a shaped steel. That is, it is difficult to implement because the equipment becomes extremely expensive and the cost becomes high.

[0003]

A horizontal or vertical centrifugal casting method is generally used as a method for producing the large-sized sleeve roll. However, a high-speed tool steel (hereinafter referred to as HSS) -based material containing a few percent of each of carbide-forming elements such as Cr, Mo, W, and V is used as GNo. However, when cast at a rotational speed of around 100, there is a problem that carbide segregation occurs due to the difference in specific gravity of each element. As the inner layer material, a tough ductile material is generally used in the sleeve roll made of cast iron, but when a ductile material having a C composition exceeding 3% by weight is used in the high-speed sleeve roll, the inner and outer layer boundaries are abnormal. There is a problem that the tissue is likely to be generated and the strength near the boundary is extremely reduced, and the combination of HSS and ductile is not suitable. The present invention has been made in view of the above-mentioned problems of the centrifugal casting method, and an object of the present invention is to realize a more reliable and sound composite HSS sleeve roll used as a roll for H-section steel rolling, an edger roll, or the like.

[0004]

The composite HSS sleeve roll of the present invention has a C content of 1.8 to 3.
0%, Cr 4.0 to 8.0%, Mo 2.0 to 8.0
%, W is 2.0 to 6.0%, V is 4.0 to 10.0%,
The weight ratio of the chemical components to the outer layer made of a high-speed material having a Co content of 12.0% or less and a balance of substantially Fe is 1.0 to 1.0.
2.0%, Si 1.0-3.0%, Mn 0.2-
1.0%, Ni 0.3-1.5%, balance F substantially
It is formed by the inner layer of the spherical graphite adamite material of e.

In the method for manufacturing the composite high-speed sleeve roll of the present invention, the outer layer made of the high-speed material molten metal and the inner layer made of the spherical graphite adamite material molten metal are used as GNo. Is 50 ~
It is characterized in that it is successively cast by a vertical centrifugal casting method at a rotation speed of 80.

[0006]

The chemical composition of the material forming the outer layer is an important item that determines the performance of the roll, and the reason why the chemical composition ratio of the HSS material forming the outer layer is limited as described above will be described below. C is necessary for forming carbide to improve wear resistance. If the amount is less than 1.8%, the amount of crystallized carbide is small and the abrasion resistance is not sufficient. On the other hand, when C exceeds 3%, the amount of carbides becomes too large, the strength and toughness deteriorate, and the rough surface resistance also deteriorates in terms of roll quality.

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

[0008] V combines with C to form an MC type carbide having a very high hardness, which greatly contributes to the wear resistance of the roll. If the amount is less than 4%, the effect is insufficient, and if it exceeds 10%, it becomes difficult to finely and uniformly distribute carbides, and the rough skin resistance is deteriorated. Although Co is not a carbide-forming element, it dissolves in the matrix and increases the high temperature softening resistance of the roll, so Co is added in an amount of 12% or less, if necessary.

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

In manufacturing composite high speed sleeves, GN
o. When casting is performed at a rotation speed range of 50 to 80, the molten metal cannot be uniformly pressed against the mold if the rotational speed is less than 50 G (GNo. 50) due to insufficient centrifugal force. If it exceeds 80 G, the alloy element added in a large amount as described above is likely to segregate due to the centrifugal action, which causes a problem of causing structural abnormality.
Further, the vertical centrifugal casting method is used because when a horizontal centrifugal casting method is used to cast at 50 to 80 G, a lining phenomenon is likely to occur due to insufficient centrifugal force, which makes it difficult to obtain a sound product. Generally, 100 to 150 G for horizontal centrifugal casting and 100 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 mixed in the outer layer material into the inner layer material is large, and the toughness is reduced.

The composite HSS sleeve roll according to the present invention is a product in which a high hardness HSS outer layer having extremely excellent wear resistance and a spherical graphite adamite inner layer having excellent toughness are completely integrated. It has sufficient strength to withstand high-load rolling such as rolling, is superior in wear resistance to conventional cast iron rolls, and is expected to improve the quality of the product surface properties of rolled materials, the roll unit, and rolling efficiency.

[0012]

【Example】

Example 1. Body diameter 1000 mm, body length 470 mm, inner diameter 5
A vertical roll for H-shaped steel rolling having a thickness of 46 mm and an outer layer thickness of 100 mm (both finished dimensions) was manufactured by a vertical centrifugal casting method, and subjected to quenching and tempering heat treatment to adjust the surface hardness to HS80. The roll of Example 1 and the rolls of Examples 2 and 3 described below, and the composite sleeve rolls of the conventional nickel grain material as Comparative Example 1 and the conventional ductile material as Comparative Example 2 were used as outer layer materials. Table 1 shows the chemical components, their proportions, and the roll surface hardness.

[0013]

[Table 1]

As a result of ultrasonic flaw detection, the roll of Example 1 was found to be a sound composite sleeve roll without any harmful segregation or defects such as burrows being observed in the outer layer, inner layer and boundary. Was done. A test piece was taken from the surplus product of this roll, and the mechanical properties, metallographic structure and cross-sectional hardness distribution were investigated. The mechanical properties of Example 1 and Comparative Example 1 are shown in Table 2, the microstructures of the outer layer and the inner layer of the roll of Example 1 are shown in FIGS. 1A and 1B, and the outer layer of Comparative Example 1 (nickel: nickel). 2 (a) and 2 (b) show the microstructures of the grain 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 shown in 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. The hardness distribution of Example 1 is shown in FIG.

[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 Remarkably excellent in strength. Also,
As can be seen from FIG. 4, the outer layer hardness is substantially constant regardless of the distance from the surface, and the roll of Example 1 has a waste diameter (about 8 mm).
It can be fully expected that the wear resistance does not deteriorate up to 50 mm). According to the test use of the H-shaped steel rolling of the roll of Example 1, the average result of rolling about 50000 tons of the product is about 4000 tons / mm (abrasion amount of diameter), and the harmful cracks on the roll, No trouble such as seizure occurred, and the surface properties of the rolled material were good.

Example 2. Body diameter 780 mm, body length 290 m
A vertical roll for H-shaped steel rolling of m was manufactured. The chemical composition and proportion of the outer layer material are as shown in Table 1 above. The surface hardness of this roll is 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 detection, and is in test use for H-section steel rolling.

Example 3. Body diameter 915 mm, body length 650 m
An edger roll for rolling a thin sheet of m was produced. The chemical composition and ratio of the outer layer material and the hardness are as shown in Table 1 above. The sleeve roll of this Example 3 was heat-fitted into an arbor to form an assembled roll, which was used for continuous hot rolling for a thin plate for about 2 months. As a result, both the wear resistance and surface properties of the roll were good, and there was no trouble. It was confirmed that no accident occurred and the accident resistance was also good.

[0019]

INDUSTRIAL APPLICABILITY The present invention can realize a large-sized composite high-speed sleeve roll, such as an H-shaped steel rolling roll or an edger roll for thin plate rolling, which has been considered difficult by conventional manufacturing techniques. Moreover, since the manufacturing method applies the conventional centrifugal casting technology, no complicated technology or process control is required, the equipment does not become extremely expensive, and a sound and high-performance large composite high speed sleeve roll is provided. it can. This large-sized composite HSS sleeve roll is a complete combination of a high hardness HSS outer layer with extremely excellent wear resistance and a spherical 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 the surface properties of rolled material, the roll unit, and rolling efficiency.

[Brief description of drawings]

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

FIG. 2 (a) is a microstructure photograph showing the metallographic structure of the outer layer of a conventional roll of nickel grain material (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 a metal structure of an outer layer of a conventional ductile material roll (Comparative Example 2).

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

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B22D 19/16 D 9266-4E C22C 37/04 38/22

Claims (2)

[Claims] 1. A weight ratio of chemical components, wherein C is 1.8 to 3.
0%, Cr 4.0 to 8.0%, Mo 2.0 to 8.0
%, W is 2.0 to 6.0%, V is 4.0 to 10.0%,
In the weight ratio of the chemical composition to the outer layer of the high speed steel material having Co of 12.0% or less and the balance being substantially Fe, C is 1.0.
~ 2.0%, Si 1.0-3.0%, Mn 0.2-
1.0%, Ni 0.3-1.5%, balance F substantially
A composite high-speed sleeve roll formed by an inner layer of a spherical graphite adamite material of e. 2. An outer layer made of a melt of high speed steel material and an inner layer made of a melt of spheroidal graphite adamite material are GNo.
The method for producing a composite high-speed sleeve roll is characterized in that it is successively cast by a vertical centrifugal casting method at a rotation speed of 50 to 80.