JPS6036857B2 - Cylindrical, cylindrical wear-resistant castings and their manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wear-resistant composite casting used for rolling rolls, rollers, and other cylindrical or cylindrical castings, and a method for manufacturing the same.
The present invention relates to providing a material having excellent wear resistance and having a three-layer structure in which a high-hardness layer containing particles is integrally formed.

For example, for rolling rolls, the breast surface thereof is required to have wear resistance, and the core and neck portions are required to be soft and have strong plowing properties.

For this reason, the current common method is to use centrifugal force casting to form only the outer shell layer of the chest surface using a high-alloy material with excellent wear resistance, and then cast a tough material inside and weld the two together. Composite roles are often used. However, even with such composite rolls, there is a limit to the wear resistance of the outer shell layer made of high alloy materials, etc., and it is not sufficient for applications that require particularly high wear resistance. We are currently in a situation where we cannot afford it.

Therefore, for finishing rolls for rolling round bars and wire rods, conventionally the outer shell layer was made of high-alloy chilled material with a hardness of H
Composite rolls having around s8 sparseness have been used, but recently, as an alternative to this, rolls using sintered carbide made of WC powder have been used, and have achieved excellent wear resistance. However, with this type of sintered carbide product, it is currently impossible to manufacture large products for use in large rolls or long rolls, and there are also disadvantages in that the cost is high. The present invention was made in view of this technical background, and the outer surface of rolling rolls and other rolling rolls, which correspond to the layers in use, is particularly required to have wear resistance, while the inner layer or core thereof must have toughness. For various cylindrical or cylindrical castings that require A new three-layer structure consisting of a high-hardness outer layer that contains WC particles that exhibit high hardness and wear resistance in a nearly uniform density and a densely packed state, and a high-alloy outer layer that is formed on the inner surface of the high-hardness outer layer and does not contain WC particles. It aims to provide a layered structure,
At the same time, the present invention also provides a means for producing wear-resistant castings formed by forming a high hardness layer containing the above-mentioned WC particles.
The object of the present invention is to provide a method for easily and inexpensively manufacturing target castings using centrifugal force casting without the problems encountered with sintered products.

The present invention will be described in detail below, taking a rolling roll as an example along with a manufacturing method thereof.

First, the manufacturing method of the present invention will be described.
This method is carried out using a centrifugal casting apparatus as shown in FIG. That is, FIG. 1 shows an outline of a normal centrifugal casting apparatus used for casting rolling rolls, and in the figure, 1 is a rotary loaf, 2 is a rotary mold, and sand mold parts for forming a neck part are provided on the inner surfaces of both ends of the rotary mold. 3 is installed. Therefore, an outer layer molten metal made of, for example, high-alloy grain, high-alloy chilled, high-C adamite material, etc. is cast into such a rotary mold 2 from a ladle 4 through a trough 5, etc., and first the composite roll is cast. outer layer is far 0
When casting this outer layer, it is preferable that Ni, N
WC powder 6 plated with i-P, Ni-B, Cu, etc. and preheated to an appropriate temperature is added.

The WC powder added to the outer layer Rakuyo in this way is separated in specific gravity under the application of centrifugal force in the outer layer flaw until the outer layer solidifies based on the difference in specific gravity. That is, the outer layer is separated into a high-hardness outer layer in which WC particles are densely packed at an almost equal density in the high-alloy material that is the outer layer material, and a high-alloy outer layer that is formed on the inner surface of the high-hardness outer layer and does not contain WC particles. It is formed. Here, the above-mentioned WC, which has the most characteristics in this method,
Addition of powder will be further explained.

First, in this method, it is essential to add the WC powder by appropriately plating it with a coating material, and this is based on the following reasons. In other words, in order to form the desired high hardness layer on the outer surface of the outer layer, WC powder must be contained in the outer layer structure in the form of particles, but if WC powder is added as is, easily separates into W and CO, and the decomposed W becomes alloyed with the outer layer material, making it impossible to achieve the intended purpose. Therefore, in this method, the decomposition of this WC powder is prevented and the WC powder is effectively interposed in the tissue in the form of WC particles.
C powder that has been subjected to plating treatment is added.
At this time, the plating material must be one that is easy to plate on the WC powder, one that does not have an adverse effect on the outer layer material, and one that is low cost. Preferred specific examples are as described above. It is. When adding the plated WC powder in this manner, there is less risk of decomposition and alloying, and the effectiveness of the addition is increased.

Therefore, the amount added can be appropriately controlled according to the conditions of the target casting, and the inclusion of WC powder in unnecessary parts can be avoided, so that the amount of expensive WC powder added can be kept to the minimum necessary. In addition, since WC particles have little risk of decomposition and alloying, WC particles
In the high-hardness outer layer in which the particles are embedded, the WC particles are densely packed with almost equal density, and the hardness of the high-hardness outer layer hardly decreases over the thickness direction of the high-hardness outer layer. Therefore, if such a high-hardness outer layer is used as a rolled layer, the wear resistance will not decrease even if the rolled layer (i.e. (high-hardness outer layer) is worn away with use, and all of the high-hardness outer layer is It can be used and is extremely economical.In addition, if the outer layer material that forms the matrix structure on the outer surface of the outer layer is a low-alloy soft material, the presence of WC particles can also prevent wear from progressing from this part during use. However, the abrasion resistance as a whole deteriorates, and it is better for the roll as a whole if the high alloy outer layer that contains WC particles and is integrally formed on the outer surface is made of a material that is hard to some extent. For the outer layer material, a high alloy material having high hardness and abrasion resistance as listed above is used, since it is advantageous to ensure deformation and accident resistance during rolling as a whole.

In addition, as mentioned above, the hardness of the high-hardness outer layer hardly decreases in the thickness direction, so by interposing the high-alloy outer layer, a sudden change in hardness with the inner layer or core layer made of European material, which will be described later, can be prevented. It plays a role of softening, and can effectively prevent defects such as breakage caused by sudden changes in hardness difference. Next, in this method, it is essential to heat the WC powder to an appropriate temperature before adding it, and this is based on the following reasons. In other words, when adding WC powder without child heating, if the amount added is large relative to the amount of molten metal, the temperature of the outer layer molten metal will drop after the addition, resulting in poor flow and rapid solidification. This is because it is easy to cause cavities to occur, and it becomes difficult for the WC powder to be uniformly distributed on the outer surface of the outer layer. The preheating temperature is determined by the amount added. The temperature of the outer layer varies depending on the outer layer material, its temperature, weight, and plating material, but a range of 300 to 900 DEG C. is usually appropriate. That is, if the temperature is too low, the preheating effect will be insufficient, while if it is too high, the plating material may melt, and the equipment and costs for pretreatment will increase. Note that if the particle size of the added WC powder is too small, there will be no wear resistance effect, and there will be a problem that it will not be distributed uniformly when added to the molten metal.On the other hand, if it is too large, the mechanical A range of 50 to 200 Buddhas is usually appropriate, although this may lead to a disadvantage of deteriorating properties.

In addition, in order to uniformly distribute the WC powder, it is preferable that the mirror temperature of the outer layer is set higher in advance by the amount of the temperature drop in consideration of the temperature drop caused by the addition of the WC powder. As described above, once the outer layer molten metal has been cast into the rotary mold 2 and the outer layer has solidified, the core material made of the European quality tough village is then cast inside the mold as appropriate in the same manner as in the case of conventional composite rolls. Molten metal is poured into the roll to obtain a composite roll in which the outer layer, core, and neck are welded and integrated.

FIG. 2 illustrates the structure of the composite roll of the present invention manufactured in this way, and in the figure, 7 is a high hardness outer layer containing WC particles, and 8 is a high hardness outer layer on the outer surface. The high-alloy outer layer is integrally formed, and numeral 9 indicates the core * and the neck portion which are welded and integrated with the high-alloy outer layer.

That is, the composite roll according to the present invention is formed by welding and integrating an outer layer made of a high alloy material and a core material made of a soft strong rut, and further, the outer layer is made of a high alloy material with excellent high quality. It has a three-layer structure consisting of a high hardness outer layer that contains WC particles that exhibit hardness and wear resistance characteristics in a densely packed state at an almost equal density, and a high alloy outer layer that is formed on the inner surface of the high hardness outer layer and does not contain WC particles. It is characterized by having.

Although the above has been described using rolling rolls as an example, the present invention can be similarly applied to various rolls, lo-fus, liners, sleeves, and other cylindrical or cylindrical castings that require wear resistance on the outer surface side. Needless to say, especially when applied to cylindrical castings, the inner layer may be cast by a centrifugal casting method after the outer layer is cast.

It is also possible to cut it into several pieces and use it as a composite ring. Although the illustrated example shows the case of horizontal centrifugal force casting, it is of course possible to apply an inclined type to the manufacturing method of the present invention. Next, specific examples of the present invention will be described.

Example roll dimensions 2900 x 400 mm (mold dimensions inner diameter 300 J
A composite roll for rolling (body length: 450 ribs) was manufactured using the following materials and conditions: However, the casting conditions were: outer layer mirror temperature 14
000O WC powder addition conditions 100-15 hesh is plated with Cu, 8
Preheated to 50 degrees Celsius, 58k9 when the sun sets on the outer layer.
Addition (equivalent to an area ratio of approximately 50% WC particles from the outer surface of the roll 8 to the 2 mm thick part).

Rusted wall thickness, extra weight layer 4 sails
108k9 core material 42
5k9 chemical composition (weight%) coin material C Si M
n P S Ni Cr Mo outer layer 3.
21 0. False 0.31 0.101 0.045 3
．． 54 1.21 0.25 core village 3.35 1.1
2 0.54 0.094 0.0611.03 0.
41,0.09 The thus obtained roll had the expected three-layer structure, and the outer surface of the roll contained WC particles densely packed at almost the same density, and had high hardness with excellent wear resistance. An outer layer was formed, while no influence of W was observed on the high-alloy outer layer and core material, confirming that the desired strength was maintained.

The microscopic structures of the high-hardness outer layer of this composite roll, the high-alloy outer layer made of chilled high-alloy material, and the core material made of high-grade cast iron are shown in FIGS. 3, 4, and 5.

As explained in detail above, the present invention is applicable to rolling rolls and other rolling rolls in which wear resistance is particularly required on the outer surface side corresponding to the layer used, while on the other hand, the inner layer or core portion thereof is required to have strong balling properties. For cylindrical or cylindrical castings, without adversely affecting the inner layer or core material, the outer layer is a high hardness outer layer containing WC particles in a high alloy material at an almost equal density, and the high hardness outer layer. and a high-alloy outer layer that does not contain WC particles, the outer surface of the outer layer can have extremely high wear resistance.
Furthermore, since this high-hardness outer layer has almost no change in hardness in the thickness direction, there is no decrease in hardness even if the surface is worn away, and the high-hardness outer layer as a whole has excellent wear resistance.

Furthermore, since the base in which the WC particles are embedded is made of a high-alloy material, it is difficult for wear to proceed from this base portion, and the wear resistance as a whole is less likely to deteriorate. In addition, by forming a high-alloy outer layer on the inner surface of the high-hardness outer layer, it is convenient for ensuring the deformation and accident resistance of the casting as a whole, and there is also a hardness gap between the high-hardness outer layer and the inner layer or core layer. This can effectively prevent quality defects caused by differences in hardness. In addition, the present invention, along with its preferred manufacturing method, can be easily and inexpensively applied to large products and rolls with long bodies by using centrifugal force casting, and overcomes the drawbacks of conventional solid cemented carbide products. It could have been done.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the manufacturing process of a composite roll according to the present invention, and FIG. 2 is a cross-sectional view showing the structure of the composite roll according to the present invention. Figures 3 to 5 are micrographs showing the structure of each part of an example of a composite roll according to the present invention, in which Figure 3 shows the high hardness layer, Figure 4 shows the high alloy outer layer, and Figure 5 shows the core. It shows the material. 7...High hardness layer, 8...
High alloy outer layer, 9... core and neck. Figure 1 Figure 2

Claims (1)

[Claims] 1. A cylindrical or cylindrical composite casting formed by welding and integrating an outer layer made of a high alloy material and an inner layer or core material made of a soft and tough material, wherein the outer layer contains W in the high alloy material.
A cylindrical, cylindrical, wear-resistant casting characterized by comprising a high-hardness outer layer containing C particles in a densely packed state at an approximately equal density, and a high-alloy outer layer formed on the inner surface of the high-hardness outer layer and containing no WC particles. 2 In centrifugal casting of cylindrical or cylindrical composite castings, when pouring the outer layer molten metal, Ni and Cu are added to the molten metal.
WC plated and preheated with metal based on
A high hardness outer layer containing WC particles and a W
A cylindrical or cylindrical shape characterized by casting an outer layer integrally formed with a high alloy outer layer that does not contain C particles, then casting an inner layer or a core material molten metal into this outer layer and welding and integrating the two. Manufacturing method for wear-resistant castings.