JPS5924568A - Roll for rolling h-beam - Google Patents

Abstract

PURPOSE:To improve service characteristics such as abrasion resistance as well as fracture resistance by melt sticking the outside layer and inside layer which are incorporated therein with prescribed ratios of C, Si, Mn, P, Fe, etc. and are adjusted to prescribed hardness to one body. CONSTITUTION:A titled roll is manufactured by melt sticking an outside layer of a high C% adamite material having 55-72Hs hardness and an inside layer of 45-55Hs hardness to one body. Said outside layer contains, by weight %, 1.8- 2.8 C, 0.2-1.2 Si, 0.4-1.5 Mn, <=0.1 P, <=0.1 Si, 0.5-2 Ni, 0.5-2 Cr, 0.5-2 Mo, and the balance Fe. The inside layer contains, by weight %, 1.2-1.8 C, 1-2.2 Si, 0.2-1 Mn, <=0.1 P, <=0.1 Si, 1.2-2.4 Ni, 0.1-1 Cr, 0.3-1 Mo, and the balance Fe. This roll has excellent service characteristics such as abrasion resistance and embrittlement resistance as well as fracture resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in rolls used for rolling H-shaped steel.

When rolling H-shaped steel (1), productivity improvement 1 quality? +
ff1. From the viewpoint of safety, it is common to use a universal mill as shown in Figure 1. Among the rolls that make up this universal mill, its horizontal roll (sleeve) (
2) is assembled by shrink-fitting to the arbor (3) as shown in Figure 1, so in addition to the stress caused by the eager buckwheat rolling load during rolling and the residual stress inherent in the roll, the stress due to shrink-fitting There are many cases of breakage accidents occurring from the shrink fit surface. On the other hand, the vertical roll (4), as shown in Fig. 2, has a cavity (5) into which the bearing is inserted, and immediately outside the cavity (5) is a shell-like type (5) as shown in the figure. Or blind hole 111 (screw type) bearing fixing hole (5)
This bearing fixing hole (5) 1
Thermal stress during rolling, stress due to rolling load, and residual stress are concentrated at green If <, and the incidence of breakage accidents is high.

Conventionally, this type of rolling roll has been separated into a used layer (outer layer) and an inner layer, and measures have been taken to reduce residual stress and strengthen the inner layer.

However, heat treatment to remove residual stress may deteriorate the wear resistance of the outer layer, so there is a limit. It is also conventionally used as a material that is compatible with its inner layer.

Ductile cast iron, maleapole cast iron, and graphite steel are generally known, and among these, graphite steel exhibits the best properties, but even in these cases, breakage accidents occur under severe rolling conditions.

In view of these problems, the great invention was to improve the cracking resistance of the H-shaped steel rolling roll (horizontal roll (21, It provides an excellent roll.
The present invention provides an H-type steel rolling roll having a novel composite structure in which an outer layer and an inner layer are welded and integrated, each of which is made of the materials described in detail below.

The outer and inner layer side chambers constituting the roll of the invention will be explained below.

[Outer layer]

Since the outer layer is in direct contact with the rolled material, it needs to have wear resistance, seizure resistance, and roughness resistance, and care should also be taken not to significantly increase residual stress. Therefore, the so-called high C% adamite side chamber having the following component composition having a matrix structure mainly composed of pearlite is suitable for the interpenetration of the outer layer. That is, the outer layer is 01.8~2.8, Si
0.2-1.2, Mn 0.4-1.5, po, i or less, 80.1 or less, NiO, 5-2.2, Or 0
．． Contains each weight% of 5-2.0°Mo 0.5-2.0,
The remainder consists of 1pe and impurities, hardness Hs 55-7
It is characterized by having 2. The reasons for limiting the above component ranges are listed below.

C1.8~2.8% The amount of eutectic cementite (hereinafter simply referred to as cementite) in the outer layer is determined by the C content, and the wear resistance of the material,
The crack resistance is almost determined. If it is less than ClB%, the amount of cementite is small and the desired wear resistance cannot be achieved. On the other hand, if the content exceeds 2.896, the amount of cementite becomes too large, deteriorating heat crack resistance, and causing cracks and wear, making it impossible to expect good results.

SiO, 2-1.2% Sl is included because it has a deoxidizing effect. If the content is less than 0.291%, no effect can be expected, while if it exceeds 1.2%, the tendency for Sl dissolved into the ferrite to deteriorate the toughness of the material becomes significant, which is problematic.

Mn 0.4 to 1.5% Mn has the effect of increasing hardness and wear resistance, except in the case of S, but if it is less than 0.4%, the effect is small; on the other hand, 1.59
This is because if it exceeds 6, the material becomes brittle.

P O, 1% or less P increases the fluidity of the molten metal and improves wear resistance and burn resistance, but since it makes the material brittle, the less the better, and it should be 0.1% or less.

S o,i 96 or less S also makes the material brittle like P, so it is set to 0.1% or less.

NiO, 5 to 2.2% Old material shifts the pearlite transformation to the long-term side in the A1 transformation of the material, and contributes to improving hardness and wear resistance by forming the base into hard pearlite and bainite.

However, in order to obtain a lever effect, the content must be 0.5% or more. However, if it contains more than 2.2%.

This is because pearlite transformation and bainite transformation are delayed too much, making it easy for martensite to appear, causing problems in terms of roughness resistance and residual stress.

CrO, 5 to 2.0% Or is effective in stabilizing cementite and improving the wear resistance of the base, and for this purpose, it is necessary in an amount of 0.5% or more. However, if the content exceeds 2.096, the cementite tends to become net-like and is likely to cause casting cracks, so 2.096 is set as the upper limit.

Mo 0.5-2.0% Mo has the same effect as N1, and 0.5% or more is required to improve hardness, wear resistance, and toughness. But 2
, if it exceeds 0%, it becomes too hard and brittle) and is also disadvantageous from an economical point of view.

The outer layer basically contains the above components, with the remainder consisting of Fθ particles and impurities. Note that if necessary, 1i is applied to the outer layer.
In place of '1e, the following elements can be contained at appropriate times.

When the outer layer of paulownia containing one or more of 'ri, j'J, and Zr is cast by centrifugal force casting β, casting defects are likely to occur due to gas. Therefore, when Ti, AJ, or Zr is added alone or in combination as a deoxidizing and denitrifying agent, its soundness is improved. It should be noted that if too much of these is added, it will inhibit the fluidity of the molten metal, so the total amount is limited to 0.1% by weight or less.

One or two types of Nb and V Both Nb and ■ are effective in refining the casting structure.

It also produces hard carbide, contributing to improved wear resistance. Therefore, if Nb and (2) are contained alone or in combination, it is possible to further improve the rolling performance. However, since the above effects become saturated when the content exceeds 1.096, the upper limit is set at 1.0 weight:Iii%.

Hardness I (855 to 72) From the standpoint of wear resistance, it is necessary for outside 7FI to have a hardness of H[!55 or more].In other words, less than H855 is sufficient in terms of wear resistance, This is because the compressive strength will also be low, and compressive fracture will occur due to high rolling loads.On the other hand, if it exceeds H872, the amount of martenzite precipitation must be increased, and in that case, plastic flow will occur and the resistance will deteriorate. Skin roughness deteriorates and residual stress is not possible A
ll K JVI will cause great problems. With the outer layer of paulownia according to the great invention described in Section 2, a hardness within the desired target range can be obtained by subjecting it to an appropriate heat treatment described below.

[Inner layer]

The inner layer needs to have high toughness, especially fatigue strength. However, in the great invention, C10, inner layer t = x C1,2 ~ 1.8
, S11.0-2.2, Mn 0.2-1.0, Po,
1 or less, S Q, 1 or less, Ni 1.2 to 2.4,
Or 0.1~1. Each g of OlM o 0.3-1.0
+', Jet%, the remainder being Fe and impurities, and having a hardness of −Iq of 45 to 55. The reasons for limiting the above component ranges are listed below.

It is made of so-called graphite steel, which is characterized by suppressing the crystallization of cementite and imparting toughness by crystallizing C1.2 to 1.8%, of which 11.1 is black sharp. The lower the C content in the wood interlayer, the better the toughness, but on the other hand, the castability deteriorates, and the larger the difference in C content with the outer layer material, the more likely nest-like defects will occur at the boundary. . On the other hand, if the C content is too high, the graphite shape becomes flaky and the desired toughness cannot be exhibited. Therefore, the range is limited to C1.2 to 1.896 as the 16Σ range that does not cause these problems and exhibits the desired toughness.

St 1.0-2.2% 51ii An element that promotes the crystallization of graphite. If it is less than 1.0%, the amount of Vi graphite is small and the toughness is insufficient, while if it is 2.2%
If it exceeds this, there will be no problem in terms of graphite content, but Si dissolved in solid solution in the ferrite will cause the base to become brittle, causing problems.

Mn 0.2-1.0% Mn combines with S and is effective in removing the adverse effects of S. However, if MnO is less than 29, there is no effect, while if it exceeds 1.096, the toughness of the treetops will deteriorate.

9001% or less P l'J: Increases the fluidity of the molten metal, but does not make the ear material brittle, so it should be 0.1% or less.

S O, 1% or less Similarly to P, S should be 0.196 or less to avoid making the quality weak.

Since Ni 1.2 to 2.4% old increases interpenetrating hardenability, it has a great effect on toughness, especially fatigue strength. In order to ensure the desired fatigue strength, especially for wood materials, where fatigue strength is required.
' Contain 1.2% or more of Ni. However, 2.4%
If it exceeds 24%, marten-reite tends to form and the toughness deteriorates, so it should be kept at 24% or less.

Or 0.1~1.091y Cr is effective for toughening and stabilizing cementite,
In order to ensure toughness, the content is 0.1% or more, but 1.
If it exceeds 0%, hardly any graphite will crystallize and the toughness will deteriorate, so it should be set to 10% or less.

Mn 0.3-1.0% MO has the same effect as the old one, and 0.3% to 1.0% Mn has the same effect as the old one.
Contains 3% or more, but on the other hand, 1.0% makes the material hard and brittle.
Keep it below.

The inner layer material basically contains the above components, with the remainder consisting of Fe and impurities. If necessary, F
In place of e, the following elements can be contained in appropriate amounts, and can also be inoculated.

T1, A4. Since one or more Zr inner layer materials are also likely to cause casting defects due to gas during casting, these elements can be added to improve the soundness of the inner layer material. In this case, all of the above elements are strong degassing agents, and if they are added in too large a quantity, the fluidity of the molten metal will deteriorate and structure defects will more likely occur. 0.1% by weight
The following five items should be kept in mind.

Inoculation It is generally known that good results can be obtained if inoculation is performed for the purpose of promoting graphitization and group formation. For wood quality, we apply inoculation technology to inoculate the wood with C before casting.
a5t, FeSi, etc. inoculant for 81 minutes and 0.1
Addition of up to 1.0% is more effective in improving toughness. Inoculation Jft is not effective when it is less than 0.1%, and the effect is saturated when it exceeds 1.0%.

In addition, even in the case of inoculation, the components are adjusted so that the 81 content m after inoculation is within the range of 1.0 to 2.2%.

Hardness H: 45 to 55 The inner layer must have a hardness of H845 or higher from the viewpoint of toughness. That is, toughness also has a correlation with hardness, and if it is less than H845, toughness, especially fatigue strength, will be low, and the incidence of breakage accidents will be high during long-term use. On the other hand, if it exceeds H855, there is no problem in terms of fatigue strength, but it deteriorates in terms of toughness, reduces safety against impact loads, and is more likely to cause breakage 4r failure. Regarding the inner layer material according to the above-mentioned great invention, suitable materials may be used as described below. By applying this, the desired target hardness force of 1 mm can be obtained.

Next, a method for manufacturing a roll according to the great invention will be briefly explained. Hollow rolls (sleeves) for such purposes can be easily manufactured by using the centrifugal sashing method (horizontal, vertical, and inclined types).

For example, as shown in FIG. 3, a centrifugal SO production mold is constructed by installing sand molds or heat-resistant bricks (7) on the inner surfaces of both ends of a rotary mold (6), and a ladle (8) and an outer layer a. By sequentially casting the molten metals of the molten metal and the inner layer at appropriate timings, a desired composite roll that is metallurgically bonded together is manufactured by Vf. In addition, when casting the inner layer molten metal, as shown in Fig. 4, it is possible to stand the SO mold that has cast the outer layer upright and insert it into the stirrup for static casting. perforate its core).

By centrifugally casting the outer layer and then centrifugally casting or statically casting the inner layer, a product having a desired shape and wall thickness can be easily manufactured. By the way, in the product manufactured as described above, there is a thickness of 10 mm at the boundary between the outer layer and the inner layer.
Although it is unavoidable that a mixed layer (intermediate material of the outer layer and inner layer) of ~20 tnm is generated, the formation of this mixed layer does not pose any problem. Note that if the C content in the inner layer is low and the difference is large compared to the outer layer, it is a good idea that nest-like defects are likely to occur near the boundary due to the solidification form.

In this case, as a countermeasure, it is effective to interpose an intermediate layer (a material with a C content intermediate between that of the outer layer and the inner layer) with a thickness of 10 to 40 layers, if necessary.

The roll heat treatment method according to the great invention involves heat treatment that raises the temperature to the austenite region, tempering, and strain relief for the purpose of ensuring the toughness of the material, adjusting hardness, and improving wear resistance. eutectoid variable a! Heat treatment is performed at a humidity of 8 or less.

Next, examples of the great invention are listed below along with comparative examples.

<Example> Using the outer layer and inner layer materials listed in the table below, each
A composite roll of 0- was manufactured. The hardness distribution of the example product is shown in FIG.

However, outer layer thickness: 180 questions, inner layer thickness: 95 mm (of which, the intermediate range of interoperability between the outer layer and inner layer is between 20 mm) Table: Chemical composition (wt%) Hardness measurement value: 250 mm from the roll surface Example Ha 47.7 ( (See Figure 5) Comparative example H day, 40.3 Mechanical properties: Tensile strength elongation for 250 minutes from the roll surface Fatigue strength (rotary bending 10' times) Example 65.3 immediately 4rl 1.93% 29 to φd
Comparative example 62.9Kll//IJ 2.24% 2
Residual stress value of 2φ: Inner surface line direction Example 12.3 Kφd Comparative example 11.8 Kt/mr1 As explained in detail above, the present invention applies to horizontal rolls and vertical rolls used for rolling H-shaped steel, The circular layer is made of high C% adamite abrasive material with a specific composition and a base structure mainly composed of fine pearlite, while the circular layer is made of graphite steel with a specific composition and excellent toughness, especially fatigue strength. However, since these are integrated and welded together, it has superior usability characteristics such as wear resistance, roughness resistance, and seizure resistance on one side compared to conventional products, and at the same time has excellent cracking resistance. Excellent safety was provided.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view showing the state of rolling of H-beam steel by a universal mill. Figure 2 (1), (b) l-
, 1: A front sectional view and a side view showing the vertical roll. FIG. 3 and FIG. 4 are both sectional views showing a manufacturing process for a composite roll according to the present invention. FIG. 5 is a diagram showing the measured hardness distribution in the radial direction of an embodiment of the roll of the present invention. a...Outer layer, b...Inner layer Patent applicant: Kubota Iron Works Co., Ltd. Procedure assistance
Authorized (self-motivated) October 4, 1980 Mr. Commissioner of the Japan Patent Office 1 Indication of the case 1982 Patent Application No. 134043 2 Title of the invention Applicant: P Terrakura (105) Kubota Tekko Co., Ltd. 4, Agent address: 11013 Go Tg, Higashiosaka City, Osaka Den J
, Josaka f061+7R2) [HK 'A5 Rejection 11i
Yama Notification Day I/J Showa Year Month Day (Voluntary) 6, Subject of amendment/Oshiichisho 2, Claims 1, C1,8 to 2,8, SiO,2 to 1.2 , Output 0.
4-1.5, Po, 1 or less, 5O11 or less, NiO,
5-2.0, CrO, 5-2.0, Mn 0.5-2
．． an outer layer having a hardness of Hs 55 to 72 and consisting of Fe and impurities in each weight%;
2-1.0, PO11 or less, S, 0.1 or less, Ni
1.2~2.4, CrO, 1~1.0, Mo0.3~
1. A roll for H air-conditioned rolling, comprising an inner layer having a hardness of 11s45 to 55, containing 1.0% of each weight, the balance F'e and impurities, and an inner layer having a hardness of 11s45 to 55. 2. Special feature where the outer layer contains one or more of Ti, At, and Zr in a total amount of 0.1% or less instead of Fe]
A rolling roll according to claim 1. 3. The rolling roll according to claim 1 or 2, wherein the outer layer contains 1.0% or less of Nb, 1 or 2 types of Nb and 2 in place of Fe, respectively. 4. The inner layer is made of 'l゛i, At, Zr instead of Fe.
The rolling roll according to claim 1, 2, or 3, which contains one or more of the following in a total amount of 0.1% by weight or less.

Claims (1)

[Claims] L C1,8-2.8, SiO,2-1.2, Mn
O, 4 to 1.5, P'0.1 or less, 30.1 or less, old 0.5 to 2.0, Mo 0.5 to 2.0, each weight%
hardness H day 5, consisting of 5% Fe, I, and impurities
5-72 outer layer, C1,2-1.8, Si1.0-2.2, Mn
0.2-1. OlP O, 1 or less, 5O11 or less, old 1
．． 2-2.4, cr o, i ~1.0. A roll for H Qp jil rolling, characterized in that it contains Mo 0.3 to 1.0% by weight and is integrally welded with an inner layer having a hardness of H845 to H845 and H845 to H55, the remainder being Fe and impurities. 2. The rolling roll according to claim 1, wherein the outer layer contains one or more of Ti, A4, and Zr in a total amount of 0.1% by weight or less in place of Fe. & Claims 1 or 2 in which the outer layer contains 10% by weight or less of one or both of Nb and V in place of Fe.
Roll for rolling as described in section. The rolling roll according to claim 1, 2, or 3, wherein the surface inner layer contains one or more of Ti, Al, and Zr in a total amount of 0.1% by weight or less in place of Fe. .