JPS59183909A - Composite sleeve roll for rolling H-type steel and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite sleeve roll that has better wear resistance and accident resistance than conventional rolls as a roll for H air-conditioned rolling.

When rolling H-shaped steel, it is common to use a universal mill from the standpoint of productivity and quality assurance, but most of the rolls used in this universal mill, namely horizontal rolls, vertical rolls, and edge rolls, are Adopts sleeve roll method.

In the casting of sleeve rolls, composite casting using centrifugal force casting as shown in FIG. 1 is generally adopted in order to improve the quality of the material and the casting yield. That is, first, the outer shell molten metal is centrifugally cast, and after it is unsolidified or solidified, the inner shell molten metal is centrifugally cast, and the two are welded and integrated.

Since the inner shell material reinforces the roll, special attention must be paid to its toughness. On the other hand, since the outer shell material is in contact with the rolled material and is directly linked to rolling performance such as wear resistance and roughness resistance, improving the outer shell material is the most important matter. In particular, in the case of horizontal rolls, sliding wear with the 7 langes of the H-beam steel is severe, and among the properties generally required in hot rolling (crank resistance, seizure resistance, roughening resistance, wear resistance), Abrasion resistance is important. Further, with regard to vertical rolls and edge rolls, there is a growing demand for improved wear resistance as the number of rolling machines increases recently.

Conventionally, H855-65 adamite material has been used for this outer shell material, but there are problems in terms of seizure resistance and roughness resistance, and increasing the hardness to H865 or higher is difficult due to manufacturing technology and It is said to be difficult due to the problem of accidents occurring during use.

In addition, in composite three rolls, in order to prevent accidents when using the rolls, it is necessary to thoroughly weld the outer shell and inner shell, and from this point of view, composite technology is also an important issue. .

In view of these circumstances, the present invention has a material with an outer shell material of 65 to 80%.
A new type of H is made by integrating a high chromium material with high He hardness and a spheroidal graphite cast iron material with excellent toughness and accident resistance as the inner shell material, and welding these outer and inner shell materials together.
The purpose of the present invention is to provide a composite sleeve roll for air-conditioned rolling, and at the same time, to provide a suitable manufacturing method thereof by centrifugal casting. 3.2%, Si 0.5-1.
5%, Mn 0.5-1.5%, 2061% or less, 5
O 11% or less, Ni O, 8~2.5%, Cr 10~
254, Mo 0.5-2.0% Nb 1.0% or less, V 1.0% or less Remaining J Outer shell consisting essentially of Fe, C2.8-3.8%, Si1. f3~6.2%, Mn
0.3-0.8%, po, +% or less, 8002% or less, Hx 1.5% or less, Cr 1.5% or less, MoO
, 6% or less, Mg0.02-0.1% balance substantially Fe
The inner shell is welded and integrated with the inner shell. In the specification, all component values of chemical compositions mean weight %.

The outer and inner shell materials according to the present invention will be explained below. First, regarding the material of the outer shell, this high chromium material is specifically designed to have a hardness of 65 to 80H84, and taking other required properties into account, the range of each component is defined as shown below.

C should be within the range that stabilizes (Fe-Cr)y c3 type carbide, and should be determined by the target carbide i while maintaining a balance with Cr, but if it is less than 20%, the amount of carbide is small and wear resistance is poor. The effect on sex is insufficient, while 6.2
%, the amount of carbides becomes too large, resulting in significant deterioration in mechanical strength, especially toughness. Therefore, C2,
It is defined as 0 to 6.2%.

Sl is included to deoxidize the molten metal, and has a content of 0.5
If the content is less than 1.5%, there will be no effect, and if the content exceeds 1.5%, the mechanical properties will deteriorate and it will be difficult to obtain hardness that completely lowers the Ari transformation point. Therefore, the 51 content is 05~
The range is 1.5%.

Mr#t has an auxiliary effect in deoxidizing Si, and if it is less than 0.5%, no deoxidizing effect can be obtained. However, 1.5%
If the content exceeds this amount, the mechanical properties, especially the toughness, will deteriorate significantly. Therefore, the Mn content is also in the range of 0.5 to 1.5%.

The smaller the P content, especially in roll materials, the more desirable it is.
It is necessary to keep the content to 0.1% or less in order to make the material brittle.

Similarly to P, the smaller the amount of S, the more desirable it is, and from the viewpoint of making the material brittle, it must be kept at 0.1% or less.

N1 is added to actively adjust the hardness in order to improve hardenability.If the content is less than 0.8%, it will not have this effect, while if it is contained more than 2.5%, it will cause retained austenite. 9, especially when adjusting the hardness to H865-80, N1-containing ffi"to,
The range is 8 to 2.5%.

Cr is particularly contained in large amounts to improve toughness and wear resistance, but if the content is less than 10%, M
A large amount of gC-type carbide crystallizes, making it impossible to improve toughness and make the carbide finely uniform.If the content exceeds 0 or 25%, the amount of M23Q-type carbide increases, and this carbide becomes M7Cs. Hardness is lower than type carbide and has sufficient N resistance.
=-Abrasion resistance cannot be obtained.

Therefore, the Cr content is defined as Cr1O to 25% as the range in which C3-type carbides are crystallized at 2°C, in balance with the above specified range of C content.

MO increases the quenching and tempering resistance, and at the same time enters into the carbide to increase the hardness of the carbide and is effective in promoting tempering and softening resistance.However, if its content is less than 0.5%, this effect is small; If the content exceeds %, residual austenite will become stabilized in the matrix, and the hardness will actually decrease. Therefore, the MOC content is set in the range of 0.5 to 2.0%.

Nbl''j: Effective in refining the casting structure, Nb content promotes precipitation hardening and improves wear resistance. Especially in the hardness range of 65 to 80Hs, Nb content is 10% or less. It has a sufficient effect, but if it exceeds 1.0%, the effect will be saturated and the cost will increase.

V is contained for the same purpose as Nb, but especially in the hardness range of 65 to 80 Hs, the content may be 1.0% or less, and if it exceeds 1.0%, V carbide will form. If the amount increases, the toughness will deteriorate. Therefore, the contents of Nb and (2) are each set at 1.0% or less.

As mentioned above, the outer shell material of Honda Ru has a hardness of H865.
The range of each component is specified so as to obtain a hardness of .about.80, and the reason for considering such a range of hardness characteristics is as follows.

In general, rolls for H air conditioning rolling are required to have wear characteristics between the side wall and the H-shaped steel 7 flange, roughening of the side wall, crack resistance, 7 flange chipping resistance, etc., but the wear resistance of the roll is determined by the hardness If the hardness is less than H865, the roughness resistance and abrasion resistance tend to decrease rapidly. but,
When the hardness exceeds H880, the resistance to accidents caused by local heat generation of the roll due to abnormal rolling, the resistance to cracking, or the resistance to 7-lunge defects and the like to large rolling loads tend to deteriorate rapidly. Therefore, excellent roughness resistance,
In order to ensure wear resistance, accident resistance, and crack resistance at the same time, in the case of a high chromium material, it is best to adjust the hardness to a range of H865 to H80.

Next, regarding the inner shell material, tough spheroidal graphite cast iron material is used for the inner shell material of this roll.
d The range of each component is defined as below. Note that since a part of the inner surface of the outer shell is washed and welded to the inner shell, it is necessary to determine the composition of the molten metal for the inner shell in consideration of the amount of washing.

C is contained in order to impart toughness and strength, but if the C content is less than 2.8%, the material will become chilled and the toughness of the inner shell material will significantly decrease. On the other hand, if the content exceeds 6.8%, graphitization will be excessive and the strength of the inner shell material will be insufficient. (fitting method), a large fitting allowance cannot be achieved, leading to axial displacement of the sleeve and damage from the inside. Therefore, C2
, 8 to 68%.

Si is necessary to prevent the material from becoming brittle due to the inclusion of outer shell Cr, but if the content is less than 1.8%, graphitization will be poor and a large amount of cementite will crystallize, reducing the strength of the inner shell. Due to the deteriorating ridges and residual stress, it becomes easy to crack during casting. On the other hand, if the content exceeds 6.2%, black ship formation will be promoted and strength will deteriorate. Therefore, the S1 content is 1.8 to 3.
The range shall be 2%. Note that the 51 content can be set to the above-mentioned high range from the time of melting the inner shell molten metal, but when the inner shell molten metal is cast, ca-8i and Fe-5i'i are added at the same time.
．． Inoculation at 2-0.5% (31%) is also a very effective method, in which case the initial 51 content will be close to the lower end of the above range, giving good results. .

Mn combines with S, and as MnS, the negative influence of S is completely reduced, but this effect is small at less than 0.6%, while at 0.6%, Mn is combined with S.
If the content exceeds 8%, the effect of deteriorating the material becomes more pronounced than the effect of preventing the adverse effects of S. Therefore, M
The n content is in the range of 0.3-08%.

P increases the fluidity of the molten metal, but since it makes the material brittle, it is desirable to have a low P content, and the content needs to be 0.1% or less.

Like P, S makes the material brittle, so the lower it is, the better. Furthermore, since the inner shell is made of spheroidal graphite cast iron, it combines with Mf added during the Mt treatment to form Mn, and S is removed, but the S content must be low in order to make the graphite spheroidal. It is necessary and is specified at 0.02% or less. In addition,
Regarding the inner shell molten metal before the Mn treatment, since S is removed by the Mf treatment, a So of 0.6% or less is allowed.

Although N1 should be contained in order to stabilize graphite, there is no significant effect even if it is contained in an amount exceeding 1.5%.

Therefore, the N1 content is set to 1.5% or less.

The lower the Cr content, the better the content is 1.5% or less in view of the balance with Sl.If the content exceeds 1.5%, the material will contain more cementite and will deteriorate in terms of toughness. do. Therefore, the Cr content is set to 1.5% or less. However, regarding the molten metal in the inner shell before casting, the outer shell is made of a high chromium material, and as the two are welded together, it is inevitable that Cr will be mixed into the inner shell, so the total amount of Cr mixed into the inner shell is assumed to be 0. It is necessary to regulate the content to a low level of 8% or less.

If the content exceeds 0.6%, the material becomes too hard, so the content should be 0.6% or less.

Mn is an element necessary for spheroidizing graphite, but if its residual content is less than 0.02%, spheroidization will be poor, so the inner shell cannot be made of tough spheroidal graphite cast iron material. On the other hand, if the content exceeds 0.1%, it is unfavorable in terms of Mt's chilling effect and dross. Therefore,
The residual Mn content is in the range of 0.02 to 0.1%.

In addition, when treating the inner shell molten metal with Mt, it is necessary to take into consideration losses due to MPS and dross generation and add extra so as to obtain a predetermined residual amount.

Also included are Nb and V that are unavoidably mixed in from the outer shell.

The roll of the present invention is made of the above-mentioned outer and inner shell materials, which are welded and integrated to form a composite sleeve "J-ru".

Such composite three rolls are manufactured by centrifugal casting. This manufacturing method is explained with reference to Fig. 1. Metallic iron Qll+ is coated with a refractory on the inner surface and sand molds or heat-resistant bricks (2) are fixed on the inner surfaces of both ends to prevent the molten metal from scattering from both ends. While rotating on a centrifugal casting machine, first cast the outer shell molten metal to completely form the outer shell (3), then pour the inner shell molten metal while the inner surface is partially or completely unsolidified, A composite sleeve roll in which the outer shell (31) and the inner shell (41) are completely welded and integrated metallurgically is cast.

((5) in Figure 1 is a rotating roller, (6) is a molten metal ladle, (
71 indicates a casting machine) In the centrifugal force casting method illustrated in FIG. It is also possible to do so. Also,
When casting the inner shell (4), it is also effective to move the injection port of the casting gutter 17) from the back end of the mold (]) to the casting side end in order to ensure that the outer shell thickness is uniform throughout. It is.

Next, an example of Kihatsu (7), a comparative example, and a conventional example will be listed and explained.

(2) Table 1 shows the chemical compositions of the molten metals of Examples 1 to 6, Comparative Examples 1 and 2, and Conventional Examples. However, the same inner shell molten metal was used in Examples 1-6. Using all the molten vortex shown in Table 1, under the manufacturing conditions shown in Table 2, and using the centrifugal force casting method shown in Figure M1, a roll material with an integrally welded outer shell and inner shell is inserted, and after solidification is completed. , Composite three roll C shown in the same table
A width of 2301M) was collected.

As a result of component analysis of the outer thigh and the central wall thickness of the inner shell of the obtained product, the product composition of each outer shell was approximately the same as that of each molten metal. On the other hand, the inner shell component of the first example was as follows. (However, for the sake of caution, we omit the analysis of Nb and V.

) Inner shell product composition of Example 1 (unit: wt%) C: 3,2
9% S: 0.012% F,! p: 0.03
9%Si: 2.81% Ni: 0.58%
Mn: 0.51% Cr: 1.09%P
: 0.058% Mo: 0.31% remaining Nb, V and substantial Fe incorporated from the outer shell Table 6 shows the results of examining the mechanical properties of the thick center of the outer shell of the obtained product Shown below.

Table 6 Note that the surface hardness of Example 1 was H874 ■Evaluation From Table 6, Examples 1 to 6 of the present invention had improved outer shell hardness compared to the conventional example. Compared to Example 1.2, the improvement in toughness is significant.

As confirmed by the above examples, the composite three for H air-conditioned rolling 70-rule of the present invention has an outer shell made of a high chromium material with a specific chemical composition as described above (Fe-Cr).
17 There is a large amount of C3 type carbides, and the outer shell hardness can be in the range of H865 to 80, which makes it possible to obtain a material with particularly excellent wear resistance.Furthermore, the structure itself is Nl) , V makes it tougher and has the effect of significantly extending the life of the roll compared to conventional rolls. Furthermore, according to the manufacturing method of the roll of the present invention, which is based on centrifugal force casting, the inner shell material is also centrifugally cast, thereby reducing the amount of mixing between the outer shell and the inner shell, and achieving complete welding and integration of both. However, since high chromium content in the inner thigh material is suppressed, it is effective in preventing deterioration of its toughness and is effective in ensuring the accident resistance of the roll.

[Brief explanation of drawings]

Figure 1 shows the manufacturing method for rear pickpockets and brawls by centrifugal casting. FIG. 13)...outer shell, (4)...inner shell. Patent applicant: Kubota Iron Works Co., Ltd. Kan 7

Claims (1)

[Claims] 1% by weight: C: 2.0-3.2% Si: 0.5-1.5% Mn: 0.5-1.5% p: o, i% or less S:O , +% or less Ni: 0.8 to 2.5% Cr: 10 to 25% MO + 0.5 to 2.0% Nb: 1.0% or less ■ = 1.0% or less The remainder essentially consists of Fe Shell: C: 2.8-3.8% Si: 1.8-3.2% Mn: 0.3-0.8% P: 0.1% or less S: 0.02% or less Ni: 1 .5% or less Cr: 1.5% or less MO: 0.6% or less M7: 0.02-0.1% The remainder is unavoidably mixed from the outer shell and consists of 7'cNb, V, and substantially Fe. A composite sleeve roll for H air-conditioned rolling having an outer shell hardness of 65 to 80 H days, characterized in that the inner shell is integrally welded with the inner shell. 2 By centrifugal force casting, C: 2.0-6.2% Si: 0.5-1.5% Mn: 0.5-1.5% P: 0.1% or less S: '0 .1% or less Hl: 0.8 to 25% Cr: 1'0 to 25% MO: 0.5 to 2.0% Nb: 1.0% or less - 1.0% or less balance substantially made of Fe After casting the molten outer shell, while the inner surface is partially or completely unsolidified, C: 2.8 to 3.8.
% Si: 1.8-3.2% Mn: 0.3-0.8% P: 0.1% or less S: 0.06% or less N1: 1.5% or less Cr: 0.8% or less MO : 0.6% or less The remainder is substantially Fe and the residual Mg amount is 0.02 to 0.1
The outer shell hardness is 65, which is characterized by casting the inner shell molten metal treated with M7 to form a duck, and welding the outer and inner shells together.
A method for manufacturing a composite sleeve roll for H air-conditioned rolling having ~80H days.