JPS61219406A - Composite ring roll - Google Patents

Abstract

PURPOSE:To make an inner layer tough and to reduce the manufacturing cost of the titled roll by diffusion joining the outer layer of a high alloy steel stock, containing the respective specific amounts of C, Cr, Si, Mo, Mn, V, P, to the inner layer excellent in toughness, such as a matrix of ferrite, under a hot hydrostatic pressure. CONSTITUTION:A high alloy steel stock is constituted of the following components, by weight percent. 1.0-2.8% C, 0.2-2.0% Si, <=1.5% Mn, 2-10% Cr, 3-15% Mo, 0.1-3% V and 1-0.5% P. This high alloy steel is suitable for an outer layer stock, because of its excellent high-temp. hardness, resistance to wear and resistance to seizure. For the inner layer stock, a carbon steel for machine structural use or a alloy steel for structural use, etc. is used. These outer and inner layer stocks are fixed by shrinkage fitting to, for instance, an axis 21 having an annular projected part 22 at its central outer circumference, to use it as a built-up roll. Such roll is manufactured at low cost and is excellent in durability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ring roll for rolling steel wire rods, bars, etc.

(Prior art) Rolls for steel rolling, especially rolls for finishing rolling mills, are required to have wear resistance in the part that contacts the rolled material (used layer), so the outer layer and the used layer are made of tough materials. A composite roll is used in which the shaft core part and the core part are welded together. The composite roll is mainly integrated into a composite roll at the casting stage using a centrifugal casting method.

On the other hand, most wire rod rolling mills these days use cemented carbide sintered ring rolls. For example, in block mills, ring rolls made of cemented carbide (mainly made of WC powder and CO) as shown in Figure 6 are used. is used.

Moreover, the cough ring roll is mechanically fixed to a shaft and used as an assembly roll.

(Problems to be Solved by the Invention) When a carbide ring roll is shaft-fitted and used as an assembly roll, the entire ring is made of carbide, which is not only uneconomical but also requires a complicated assembly structure. In other words, when assembling and fixing the ring roll to the shaft, it is necessary to firmly fix it to the shaft using a fixing ring, spacer ring, etc.
This is also because it is necessary to alleviate the large difference in coefficient of thermal expansion between the shaft of the steel thread and the carbide ring material. As a result, such assembled rolls are very costly.

Therefore, there is a demand for a composite ring roll in which an expensive material is used for the outer layer used for rolling, and an inexpensive tough material is used for the inner layer. One method for manufacturing such a composite ring roll is centrifugal casting. However, in this case, when the inner layer is cast on the outer layer of high alloy material, the inner surface of the outer layer is melted and the high alloy components are mixed into the inner layer, which deteriorates the toughness of the inner layer and reduces the yield of the high alloy material of the outer layer. There are drawbacks that make it worse.

The present invention was made in view of the problems in paper, and its purpose is to provide rolling performance that is slightly inferior to that of carbide ring rolls, but
It is an object of the present invention to provide a composite ring roll that is low in cost and has a strong inner layer in which migration of components from the outer layer to the inner layer is suppressed as much as possible.

(Failure to solve the problem) The following measures were taken to achieve the above objective.

That is, the outer layer of the composite ring roll has the following chemical composition in weight percent: C: ], O-2,8% Cr: 2-10% Si
; 0.2-2.0% Mo; 3-15% Mn
:1.5% or less V:Q, l-3%P: 01~0
．． 5% The remainder was made of a high-alloy steel material consisting essentially of Pe, and the inner layer was made of a steel material with excellent toughness, and both were diffusion bonded by hot isostatic pressing.

(Function) According to the means on paper, the high alloy steel material forming the outer layer has excellent wear resistance and burn resistance, so it is suitable for the layer used in rolling, and the outer layer is made of a steel material with excellent toughness. Since these steel materials are diffusion bonded by hot isostatic pressing, the transfer of high alloy components from the outer layer to the inner layer can be suppressed as much as possible, and the toughness of the inner layer will not deteriorate.

(Example) Next, the composite ring roll of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a composite ring roll according to the present invention.

The composite ring roll 1 has an outer layer 2 formed by centrifugal casting or cast casting using a high-alloy steel material with excellent wear resistance and seizure resistance, and an inner layer 2 made of a steel material with excellent toughness.
are diffusion bonded and integrated by hot isostatic pressing (hereinafter referred to as HIP).

Such a composite ring roll 1 is made by processing an outer layer material ring 2° made of high alloy steel material and an inner layer material ring 3° formed from a strong steel material into appropriate dimensions as shown in Fig. 2 (11+21). Thereafter, the two are fitted and diffusion bonded by HIP processing, and the resulting composite material is processed into a desired shape.

In this case, the outer diameter of the outer layer material ring 2°, l, is the first
The outer diameter D1 of the product in the figure is made larger by the machining allowance, and the inner diameter D2 is the diameter D2 of the boundary between the outer N2 and inner N3 of the product.
Assume that it is the same as On the other hand, the outer diameter of the inner layer material ring 3 is D2
Naturally, its inner diameter D3° is made smaller than the product inner diameter D3 by the machining allowance on the inner surface. Also, the width of the material ring is made larger than the product width in consideration of the amount of processing required. The thus obtained outer layer material ring 2'' and inner layer material ring 3'' are diffusion bonded by HIP processing.As a result, the incorporation of Cr from the outer layer to the inner layer is suppressed as much as possible, and both are made strong. A composite material is obtained which is integrated with the two.

The chemical composition of the high alloy steel material forming the outer layer is limited for the following reasons. Hereinafter, the unit is weight%, and the remainder is Pe.
and unavoidably mixed impurities.

C: 1. O~2°8% C forms a composite carbide and improves the hardness, abrasion resistance, etc. required for a roll material. If it is less than 1.0%, there will be insufficient bulk cementite and sufficient hardness will not be obtained. on the other hand,
If it exceeds 2.8%, the amount of massive cementite becomes excessive, resulting in a lack of toughness and causing rough skin.

Si: 0.2-2.0% Si is contained at 0.2% or more to ensure melt flowability,
Further, although about 0.2% of Ni is unavoidably contained in the raw materials used, if it is contained in excess of 2.0%, it is not preferable because it causes a decrease in toughness.

Mn: 1.5% or less Mn is also unavoidably contained in the raw materials used, but
If it exceeds 1.5%, it is not preferable because it causes a decrease in toughness.

Cr: 2-10% Cr is a carbide-forming element, and in the case of this roll material, it is an element necessary to generate hard massive cementite and ensure wear resistance. If it is less than 2%, there will be little lumpy cementite and it will be difficult to ensure wear resistance, while if it exceeds 10%, there will be too much lumpy cementite and the toughness will decrease.

Mo: 3 to 15% Mo is one of the main components of the roll material according to the present invention, and is an element that forms a high hardness carbide to improve wear resistance and provides softening resistance during strain relief heat treatment. It is. If it is less than 3%, the hardness necessary to dramatically improve wear resistance cannot be obtained, while if it exceeds 15%, there will be too much bulk cementite and the toughness will deteriorate.

V: Q, 1 to 3% ■ forms hard massive cementite and provides excellent wear resistance to non-rich materials, and also prevents the formation of net-like massive cementite in cast materials and forms independent massive cementite. to improve toughness. If it is less than 0.1%, there is no effect on the independence of massive cementite, while if it exceeds 3%, there will be too much lumpy cementite and the toughness will decrease.

p: o, t ~ 0.5% P forms a quaternary eutectic with Pe, Mo, and C, but
This quaternary eutectic peels off from the roll surface during rolling, acts as a lubricant, and provides extremely good seizure resistance. If it is less than 0.1%, the amount of quaternary eutectic is small and it is difficult to expect an effect of improving seizure resistance. On the other hand, if it exceeds 0.5%, the quaternary eutectic becomes excessive, resulting in a decrease in toughness, which is not preferable.

A high-alloy steel material composed of paper-like components has high high-temperature hardness and excellent wear resistance and seizure resistance, so it is suitable for use as a rolling layer.

The steel material used for the inner layer can be appropriately selected from materials such as mechanical structural carbon steel and structural alloy steel, which generally have excellent toughness. In particular, when using low-carbon, low-alloy steel consisting of a ferrite base,
It is suitable for HIP treatment and for hardening the composite material. That is, since the material made of such a ferrite base has a small coefficient of thermal expansion, it is less deformed even by temperature changes during thermal cooling of HIP processing oil, and cracks and peeling do not easily occur at the diffusion bonding surface. In addition, composite materials are subjected to quenching and tempering heat treatment to make the outer layer superior in wear resistance, but if the above-mentioned ferrite-based low-carbon, low-alloy steel material is used for the inner layer, the entire composite material can be quenched. However, the quenching action does not reach the inner layer, so no deterioration of toughness occurs. If the inner layer has a hardening effect, it is undesirable because breakage tends to occur when the ring roll is fitted into an assembled roll. It is also possible to subject only the outer layer of the composite material to quenching heat treatment, but the work is more complicated and lower in productivity than treating the entire composite material. In some cases, the rollers are used as they are without being assembled on a shaft, as shown in FIG.

That is, as shown in FIG.
It is also possible to shrink-fit the composite ring roll l, spacer ring 24 or/and end ring 25 to the shaft 23 and use it as an assembled roll, as shown in FIGS. .

It goes without saying that when assembling the composite ring roll 1 to the shaft, one composite ring roll or two or more composite ring rolls may be assembled depending on the type of rolling mill.

Further, the shaft material is generally made of a steel material that is strong and can be fixed by welding, but if the rolling load is small, it is of course possible to use a cast iron material such as ductile cast iron.

Next, specific examples will be listed and explained.

(Example) Outer diameter D1-φ320++n, inner diameter D3-φ180 Hoho,
Manufacturing example of a composite ring roll with outer layer/inner layer boundary diameter D2-φ260 and width 20 (In).

+11 High alloy steel material with the composition shown in Table 1 and C; 0
．． 24%, Si:O, +1%, Mn: 0.44
%, the balance being substantially Fe, and a material ring with the following dimensions was manufactured.

・Outer layer material ring DI'-ψ323, D2-ψ260, lI@20
5mm, inner layer material ring D2-φ260, D3'-φ175, width 205mm
(1st table) Unit weight %, the remainder is substantially Fe (2) Fit the outer layer and inner layer material rings and apply pressure 2
00 kg/c+A, temperature 1140°CT: HIP
After processing, both parts were diffusion bonded to obtain a composite material.

(3) Thereafter, the composite ring roll was subjected to quenching and tempering heat treatment, and then machined to obtain a composite ring roll.

The hardness of the outer layer of the product was 87 Its, and the hardness of the inner layer was 34 IIs.

(4) Prepare 21 [1i1 of each of the above composite ring rolls, shrink-fit and fix them to the shaft as shown in Fig. 3, and make the body length 500u+
An assembled roll for rolling steel bar No. 1 was obtained.

(Effect of the invention) As explained above, the composite ring roll according to the present invention has
The outer layer is made of high-alloy steel material with excellent wear resistance and copper lumpability, and the inner layer is made of a strong copper phase, which makes it a low cost roll for rolling steel wire rods, bars, etc. Moreover, it has an excellent lifespan. In addition, since the outer layer and the inner layer are diffusion bonded by the Hl l) treatment, it is possible to prevent the high alloy component from entering the inner layer from the outer layer with a high base metal phase as much as possible, and the toughness of the inner layer is not deteriorated.

Therefore, if the composite ring roll of the present invention whose inner layer is made of a tough material is applied to an assembly roll, it can be assembled to the shaft at low cost by a simple shrink fitting method, welding, screws, bolts, etc. However, it is possible to reuse the shaft.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a composite ring roll according to the present invention, and FIG.
Figure +11F2) is a cross-sectional view of a raw material ring, Figures 3 to 5 are partial cross-sectional views of an assembled roll to which the composite ring roll according to the present invention is applied, and Figure 6 is a cross-sectional view of a conventional ring roll. l - composite ring roll, 2 - outer layer, 3 - inner layer.

Claims (1)

[Claims] 1. Chemical composition in weight%: C: 1.0-2.8% Cr: 2-10% Si: 0.2-2.0% Mo: 3-15% Mn: 1 ．．
5% or less V: 0.1 to 3% P: 0.1 to 0.5% The remainder: The outer layer of high alloy steel material made essentially of Fe and the inner layer with excellent toughness are hot isostatically pressed. A composite ring roll characterized by being diffusion bonded by. 2. The composite ring roll according to claim 1, wherein the inner layer is formed of a low-carbon, low-alloy steel material comprising a ferrite base.