KR100587495B1 - Wear resistant wc-co-steel or fe-tic-steel joining body and the manufacturing method thereof - Google Patents

Abstract

The present invention relates to a wear-resistant cemented carbide (WC-Co or Fe-TiC) -steel joint, and to a method of manufacturing the same, more specifically, wear-resistant cemented carbide (WC-Co & Fe-TiC) used as an abrasive to the diffusion diffusion It provides a conjugated body and a manufacturing method thereof. To this end, the present invention in the diffusion bonding of cemented carbide (WC-Co or Fe-TiC) to steel using a vacuum sintering furnace and hot hydrostatic molding (HIP) furnace, the first is titanium carbide alloy steel (Fe -TiC) to maintain the at least one material selected from SUS420J2, S45C, SKD61 at 1200 ℃ to 1400 ℃ for 15 minutes to 45 minutes to provide a joint manufactured by cooling, and secondly using a hot hydrostatic molding furnace Titanium carbide alloy (Fe-TiC) powder, S45C and SKD61 were charged to the cans in turn, and maintained at 1200 ° C to 1400 ° C / 12000 to 17000psi for 1 hour to 4 hours, followed by heat treatment and cooling. It provides a conjugate produced by the method comprising the process of curing by reheating in the temperature range of 900 ℃ ~ 1150 ℃ 15 minutes to 45 minutes, the third is 88WC-12Co + 50WC-50Ni + SKD61 3 through HIP Species material CA It is charged to N in order to provide a conjugate prepared by a method comprising the process of slow cooling by maintaining for 1 to 4 hours at 1200 ~ 1400 ℃ / 12000 ~ 17000psi pressure. As a result, the strength of the base material and the bonding material can be remarkably increased to reduce the detachment of the bonding material during use, and the brittle material of the brittle material is reinforced with the softness of the base material to strengthen the overall brittleness. It is effective in reducing costs.

Cemented carbide, abrasion resistance, vacuum sintering, hot hydrostatic molding, titanium carbide alloy steel, steel, tungsten carbide-cobalt alloy steel

Description

Wear resistant cemented carbide-steel joint and its manufacturing method {Wear resistant WC-Co-steel or Fe-TiC-steel joining body and the manufacturing method

1 is a design drawing showing an embodiment of a bonded body bonded titanium carbide alloy steel (Fe-TiC) and steel (steel) produced by the vacuum sintering method or hot hydrostatic molding method according to the present invention.

2 is a view showing a Can used in the hot hydrostatic molding method according to the present invention.

Figure 3 is a view showing an embodiment of a step-by-step heat treatment process in the hot hydrostatic pressing method according to the present invention.

4 is a cross-sectional view showing a hot hydrostatic molding apparatus according to the present invention.

The present invention relates to a wear-resistant cemented carbide (WC-Co or Fe-TiC) -steel joint, and to a method for manufacturing the same, more specifically, wear-resistant cemented carbide (WC-Co or Fe-TiC) used as an abrasive, diffusion bonding to steel It provides a conjugated body and a manufacturing method thereof.

As the parts industry develops, carbides (WC-Co / Fe-TiC) are increasingly used throughout the industry as wear resistance is required for tools and molds.

Cemented carbide is an alloy of very high hardness made by firing metal carbide powder. Cobalt and small alloys, which are commonly used as a binding metal mainly composed of tungsten carbide, are cobalt. Cobalt between the tungsten particles is interposed with a melt of carbon and tungsten. In addition, it can be widely used in the sense that refers to the alloy with the metal carbide. Since the alloy of such a structure is very hard and wear-resistant, it is used for cutters (cutting machines), dies, etc. to cut or cut metal products, and also for the tip of rock drilling tools for drilling holes in rocks in mines and civil engineering. To prepare this alloy, cobalt powder and tungsten carbide powder are prepared separately, pressed and molded, and then sintered at a temperature. First, the cobalt powder is sintered (pre-sintered) at 1,000 ° C., and then finished in final form, and then 1,400 ° C. The sintering is carried out by heating with. As a result, tungsten and carbide (carbon) diffuse into cobalt to form a strong solid solution. As a result, the particles of tungsten carbide are combined to form a structure. In addition, there are three types of WC-Co-based, WC-TiC-TaC-Co-based, and WC-TiC-Co-based which are important in practical use.

However, such cemented carbides (WC-Co / Fe-TiC) have a disadvantage in that they are not widely handled because of their high wear resistance. In order to make up for this drawback, instead of using pure cemented carbide (WC-Co / Fe-TiC) when manufacturing tools and molds, cemented carbide and ordinary steel are used. Fastening, shrink fit, brazing (brazing), etc. have been used a lot in the form of, such as shrink fit and brazing method is mainly preferred. The shrink fit method is a method in which a plurality of materials to be joined are placed adjacent to each other and heated at a lower temperature than a normal firing temperature to be joined. The brazing method is a melting point of a base metal to be joined at 450 ° C. or higher. ) A method of joining two base materials by applying heat to the joining portion while the base material is not damaged, is also referred to as brazing. However, these bonding methods have a disadvantage in that the interface bonding strength of the bonded body is significantly lower, so that when the work is applied to a punch or the like, the joining part is dropped after a long time, and thus the entire mold is damaged.

The present invention has been made in order to solve the above problems, the present invention has an object to improve the bonding strength between the two materials in the manufacture of a cemented carbide and steel.

In addition, the present invention has another object to lower the manufacturing cost of the wear-resistant material by using a cemented carbide and steel joints instead of a pure cemented carbide as a wear-resistant material, and to realize a light weight of the product.

In addition, the present invention has another object to prevent interfacial peeling, cracking, etc. due to the difference in coefficient of thermal expansion generated at the interface between the two materials when the cemented carbide and steel are bonded.

In order to achieve the object of the present invention as described above, the present invention, titanium carbide alloy steel (Fe-TiC), and the step of placing the steel adjacent to each other; and after charging the adjacent materials in the sintering furnace 1300 ℃ 1600 ℃ Heating to a temperature within a range within; And cooling after the heat treatment; It provides a method of joining titanium carbide alloy steel and steel, characterized in that consisting of.

Preferably, the steel is at least one selected from SUS420J2, S45C, and SKD61.

Also preferably the sintering furnace is a vacuum furnace, the step of heat treatment is to increase the temperature to a temperature within the range of 1400 ℃ or more and 1500 ℃.

Here, the heat treatment step may further include a step of maintaining for 15 minutes to 45 minutes at the temperature.

In addition, the present invention comprises the steps of charging titanium carbide alloy steel (Fe-TiC) and steel together in a can (Can); Heat-treating the loaded materials by hot hydrostatic molding; Cooling the heat treated materials; And reheating the cooled material. Provides a method of joining titanium carbide alloy steel and steel.

Preferably, the titanium carbide alloy steel is in powder form.

Also preferably, the steel is at least one selected from SUS420J2, S45C, and SKD61.

Also preferably, the titanium carbide alloy steel, S45C, and SKD61 are loaded into the can one after the other.

Also preferably, the heat treatment temperature during the heat treatment by the hot water purification molding is 1200 ℃ ~ 1400 ℃, the heat treatment pressure is to be 12000psi ~ 17000psi.

Also preferably, the heat treatment step may further include a step of maintaining for 1 to 4 hours at the temperature.

Also preferably, the step of cooling the heat-treated material is to be a step of cooling to room temperature.

Also preferably, after the cooling, the step of processing the cooled material is further included.

Also preferably, in the step of reheating the processed material, the reheating temperature is in the range of 900 ° C to 1150 ° C.

Also preferably, the cooling may be a quenching step.

The present invention also provides a titanium carbide alloy steel and a steel joined body, which are produced by the method described above.

In addition, the step of charging a tungsten carbide-cobalt alloy (WC-Co), tungsten carbide-nickel alloy (WC-Ni), and steel in the can in turn; Heat-treating the charged materials by hot hydrostatic molding; And cooling the heat-treated material. It provides a method of joining a tungsten carbide-cobalt alloy and steel.

Preferably, the tungsten carbide-cobalt alloy (WC-Co) is in bulk form and the tungsten carbide-nickel alloy (WC-Ni) is in powder form.

Also preferably, the steel is at least one selected from SUS420J2, S45C, and SKD61.

Also preferably, the tungsten carbide-cobalt alloy (WC-Co), the tungsten carbide-nickel alloy (WC-Ni), and SKD61 may be loaded into the can one after the other.

Also preferably, the heat treatment temperature during the heat treatment by the hot water purification molding is 1200 ℃ ~ 1400 ℃, the heat treatment pressure is to be 12000psi ~ 17000psi.

Here, the heat treatment step further comprises the step of maintaining for 1 to 4 hours at the temperature.

Also preferably, the step of cooling the heat-treated material is to be a step of cooling to room temperature.

Also preferably, the cooling may be a slow cooling.

Here, the slow cooling step is to cool to a condition of 5 ℃ / hr.

Also preferably, the tungsten carbide-cobalt alloy has an alloy ratio in the range of 9: 1 to 7: 3, and the tungsten carbide-nickel alloy has an alloy ratio in the range of 4: 6 to 6: 4. do.

The present invention also provides a conjugate of tungsten carbide-cobalt alloy and steel produced by the above-described method.

Disclosed more specifically, the present invention relates to the production of double structural conjugates of cemented carbide (WC-Co or Fe-TiC) -steel using the CANNNING / HIP process or the vacuum sintering method. In particular, the CANNNING / HIP method is a method of diffusing bonding a cemented carbide (WC-Co or Fe-TiC) and steel by placing a cemented carbide and steel adjacent to each other and applying high temperature and high pressure thereto. This is a method of bonding by means of inter-diffusion of unit atoms of each material at the interface between cemented carbide (WC-Co or Fe-TiC) and steel. do. In addition, as the steel inside, it is possible to prevent brittleness of the cemented carbide (WC-Co or Fe-TiC) by joining by using powder or bulk, such as SKD61, and have high resistance to thermal shock.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and examples.

1 is a design drawing showing an embodiment of a bonded body of titanium carbide alloy steel (Fe-TiC) and steel (steel) manufactured by the vacuum sintering method or hot hydrostatic molding method according to the present invention, the manufacture of the above The method is as follows.

First, titanium carbide alloy steel (Fe-TiC) and steel are placed adjacent to each other and then charged into a sintering furnace. At this time, the sintering furnace should be maintained in an atmosphere such as vacuum or argon, and when oxygen is introduced, a problem occurs that the metal is oxidized. Therefore, a general sintering furnace should not be used.

The titanium carbide alloy steel used in the present invention further contains about 3 to 6 wt% chromium (Cr) and about 2 to 4 wt% molybdenum (Mo), and the content ratio of titanium carbide (TiC) and iron (Fe) is approximately It is manufactured to have a ratio of 1: 1: 1: 1.5.

In addition, in the steel used in the present invention, at least one selected from SUS420J2, S45C, and SKD61 is used, wherein SUS420J2 contains chromium and iron in a ratio of about 1: 10 to 1.5: 10, and nickel and carbon Is a material containing a small amount of, S45C is a material containing most of the iron and a small amount of carbon, SKD61 is a chromium and iron in a ratio of about 0.3: 10 to 1: 10, and a small amount of It is a material containing molybdenum, nickel and carbon.

In addition, the annealing hardness of titanium carbide alloy steel was 40-55 HRc, the hardening hardness was 60-75 HRc, the tensile strength was 1600-1750 N / mm <2>, and the density used the thing of 6-7 g / cm <^3> .

The thickness of the titanium carbide alloy steel and the steel shown in the drawings are represented by 15mm and 30mm, respectively, but is not limited to these thicknesses.

Next, the sintering furnace in which the materials having the above characteristics are loaded is heated to a temperature within a range of 1300 ° C. or higher and 1600 ° C. while maintaining an atmosphere such as vacuum or argon. More preferably, the temperature is raised to a temperature within the range of 1400 ° C or higher and 1500 ° C or lower and heat treated.

Here, after the temperature is raised to a temperature in the above range, it is not cooled immediately and held for about 15 to 45 minutes at that temperature. After maintaining the temperature as described above to cool the heat-treated material and the sintering furnace, it is preferable to use a slow cooling method by the air cooling method.

At this time, the surface was polished for smooth surface movement of the interface, and the joint was given a load so that the joint was well formed. The above materials are materials that do not melt even at a temperature of about 1500 ℃, the first attempt to join using a small size of the material, and then tried to join by increasing the size of the material.

In addition, the present invention also provides a method of manufacturing a joined body by joining titanium carbide alloy steel (Fe-TiC) and steel by hot hydrostatic molding method, which will be described below.

Here, the properties of the titanium carbide alloy steel and steel are as described above in the production of the joined body using a sintering furnace.

First, the titanium carbide alloy steel (Fe-TiC) and steel is charged to the can (Can).

Figure 2 is a view showing the can (Can) used in the hot hydrostatic molding method according to the present invention, the cans used when manufacturing the joined body by the hot hydrostatic molding (HIP) method is a hot hydrostatic molding by inserting a molded body Corresponding to the container, it was manufactured using S304 and SS41, respectively, and SUS304 is difficult to process due to poor workability, but excellent in weldability, less likely to leak or leak (leakage). However, SS41 was found to be excellent in terms of processability.

When the above materials are loaded into the can, it is preferable to weld with the can to fix them. After the materials are charged as above, the vacuum degassing process is performed while evacuating with a vacuum pump. At this time, sealing operation was performed so that the exhaust gas discharge port was not leaked using a hydraulic press.

At this time, the steel is in the bulk form, the titanium carbide alloy steel is charged in the form of powder and heat treatment, the steel is preferably loaded S45C and SKD61, the titanium carbide alloy steel and S45C and SKD61 in the order of charging. It is also desirable to.

Subsequently, in the step of heat-treating the loaded material by hot hydrostatic pressure molding method, the temperature increase rate up to 900 ° C. was increased to 6 ° C./min, and the temperature increase rate above 900 ° C. was about 4 ° C./min, respectively. Is 1200 ℃ ~ 1400 ℃, and the heat treatment pressure is 12000psi ~ 17000psi. If the temperature exceeds the above temperature and pressure conditions, the bonded body may be damaged or melted during the heat treatment process. Therefore, it is very important to maintain the above heat treatment conditions during heat treatment.

Figure 3 shows one embodiment of the step-by-step heat treatment process in the hot hydrostatic pressing method according to the present invention.

In the case of heat treatment as described above, it is preferable to cool after maintaining (soaking) for 1 to 4 hours at the corresponding temperature, at this time to cool to room temperature to completely cool the product. In addition, in the cooling method, it is more preferable to use a quenching method in order to proceed rapidly, but a slow cooling method may be used.

The cooled materials are processed for dimensional correction before reheating, and the purpose of further reheating is to harden the steel even more. At this time, the reheating temperature in the step of reheating is to be in the range of 900 ℃ ~ 1150 ℃.

Further, the method for joining the tungsten carbide-cobalt alloy and steel according to the present invention is as follows.

4 shows a tungsten carbide-cobalt alloy (WC-Co), a tungsten carbide-nickel alloy (WC-Ni), and steel, which are sequentially loaded into a can, as can be seen from a cross-sectional view showing a hot hydrostatic molding apparatus according to the present invention. do.

Here, the tungsten carbide-cobalt alloy is an alloy ratio in the range of the ratio of 9: 1 to 7: 3, and the characteristics of the steel as described above through the manufacturing method of the above bonded.

In addition, the characteristics of the can is the same as described above in the method of joining the titanium carbide alloy steel and steel produced by the hot hydrostatic pressing method, and the exhaust gas degassing for the hot hydrostatic pressing method is also the same as described above.

The characteristic of the above manufacturing method is to prevent defects due to thermal expansion coefficient difference generated after bonding when different materials are bonded.

That is, when manufacturing the bonded body according to the present invention, the thermal expansion coefficient difference generated at the interface of the bonded body should be overcome, in the present invention to prevent a sudden change in the coefficient of thermal expansion between the two materials and tungsten carbide to achieve a smooth change in the coefficient of thermal expansion -In the case of diffusion bonding of cobalt alloy and steel, it adopts the method of joining by introducing intermediate materials between the two materials, instead of direct joining.In this case, tungsten carbide (WC) and nickel (Ni) are used as intermediate materials to reduce the difference of thermal expansion coefficient. ) Is alloyed in a ratio of 4: 6 to 6: 4, but more preferably, the alloyed material is selected and used in a ratio of about 5: 5, and preferably the above intermediate material is used to use the hip method. Was prepared in the form of a powder to attempt bonding. In this case, however, the intermediate may be used in bulk rather than powder form. When using the powder form as described above, by introducing the interfacial material of the synthetic resin material that can be scattered during low temperature heat treatment between the tungsten carbide-cobalt alloy powder and the intermediate material powder to prevent the mixing of both materials, and then pre-baking The method of carrying out the main firing can also be considered. In addition, the width of the intermediate should also be adjusted according to the size of the product.

Thereafter, the heat treatment is performed by a hot hydrostatic pressure molding method. At this time, the heat treatment temperature is preferably 1200 ° C to 1400 ° C, and the heat treatment pressure is 12000psi to 17000psi. If the temperature exceeds the above temperature and pressure conditions, the bonded body may be broken or melted during the heat treatment process. Therefore, it is very important to maintain the above heat treatment conditions during heat treatment.

In addition, in the heat treatment step it is preferable to maintain for 1 hour to 4 hours at the corresponding temperature, and to cool the heat-treated material to room temperature at this time, it is preferable to use a slow cooling method, more specifically 5 ℃ / It is preferable to cool on the conditions of hr.

Meanwhile, as described above, the cemented carbide and steel are separated by the sintering furnace and the cemented cemented carbide and the steel by the hot hydrostatic molding method, but the method of further improving the bonding strength by performing the continuous process is also considered. Can be.

Looking more specifically, the step of placing titanium carbide alloy steel (Fe-TiC) and the steel adjacent to each other; Charging the adjacent materials to a sintering furnace and then heating to a temperature within a range of 1300 ° C. to 1600 ° C .; Cooling after the heat treatment; Charging titanium carbide alloy steel (Fe-TiC) and steel together into a can; Heat-treating the loaded materials by hot hydrostatic molding; Cooling the heat treated materials; And reheating the cooled material. Provides a method of joining titanium carbide alloy steel and steel.

In addition, in the case of the above method, since the hot hydrostatic molding (HIP) process after vacuum sintering of cemented carbide (WC-Co or Fe-TiC), internal micropores do not remain, so wear resistance is improved and high reliability of the product is expected. Can be.

The above-described embodiments of the present invention are merely exemplary, and thus, the technical spirit or scope of the present invention is not limited, and easily accessible from the claims described below by those skilled in the art to which the present invention pertains. It will be apparent that all changes or modifications derived are included in the scope of the present invention.

As described above, when the present invention is applied to a large rolling roll made of cemented carbide (Ø 410 x Ø 210 x 120t), a part of the roll is replaced with steel, thereby greatly reducing the unit cost per roll, and the roll weight is also increased. It is lighter than 30%, making it easy to handle.

In addition, by improving the bonding strength of the cemented carbide and steel by the present invention has the effect of increasing the impact resistance and heat resistance than the conventional cemented carbide rolls, by being able to manufacture a cemented carbide with a higher content of tungsten carbide than conventional alloys There is an effect that can have a higher wear resistance than conventional rolls.

In addition, when joining cemented carbide and steel according to the present invention, there is an effect that can prevent the interfacial peeling, cracking and the like caused by the difference in the coefficient of thermal expansion generated at the interface between the two materials.

In addition, there is an effect that the cemented carbide (WC-Co / Fe-TiC) can be applied to a wide range of parts that were not previously applied in the manufacture of mold parts and wear-resistant parts throughout the industry.

Claims (28)

Placing titanium carbide alloy steel (Fe-TiC) and the steel adjacent to each other; and Charging the adjacent materials to a sintering furnace and then heating to a temperature within a range of 1300 ° C. to 1600 ° C .; And Cooling after the heat treatment; Joining method of titanium carbide alloy steel and steel, characterized in that consisting of. The method of claim 1, The steel is a joining method of titanium carbide alloy steel and steel, characterized in that at least one selected from SUS420J2, S45C, SKD61. The method of claim 1, The sintering furnace is a vacuum furnace, the step of heat treatment is a joining method of titanium carbide alloy steel and steel, characterized in that the temperature is raised to a temperature within the range of 1400 ℃ to 1500 ℃. The method of claim 1, The heat treatment is a method of joining titanium carbide alloy steel and steel, characterized in that further comprising the step of maintaining for 15 to 45 minutes at the temperature. A titanium carbide alloy steel and steel joined body produced by the method of claim 1. Charging titanium carbide alloy steel (Fe-TiC) and steel together into a can; Heat-treating the loaded materials by hot hydrostatic molding; Cooling the heat treated materials; And Reheating the cooled material; Joining method of titanium carbide alloy steel and steel, characterized in that consisting of. The method of claim 6, The titanium carbide alloy steel is a joining method of titanium carbide alloy steel and steel, characterized in that the powder form. The method of claim 6, The steel is a joining method of titanium carbide alloy steel and steel, characterized in that at least one selected from SUS420J2, S45C, SKD61. The method of claim 8, And the titanium carbide alloy steel, S45C, and SKD61 are sequentially loaded into the can. The method of claim 6, The method of joining titanium carbide alloy steel and steel, characterized in that the heat treatment temperature during the heat treatment by the hot water purification molding is 1200 ℃ ~ 1400 ℃, heat treatment pressure is 12000psi ~ 17000psi. The method of claim 6 or 10, The heat treatment step is a method of joining titanium carbide alloy steel and steel, further comprising the step of maintaining for 1 to 4 hours at the temperature. The method of claim 6, The cooling of the heat-treated material is a joining method of titanium carbide alloy steel and steel, characterized in that cooling to room temperature. The method of claim 6 or 12, After the cooling, the method of joining titanium carbide alloy steel and steel further comprising the step of processing the cooled material. The method of claim 6, The reheating temperature in the step of reheating the cooled material is a joining method of titanium carbide alloy steel and steel, characterized in that in the range of 900 ℃ ~ 1150 ℃. The method of claim 13, Bonding method of titanium carbide alloy steel and steel, characterized in that the reheating temperature in the step of reheating the processed material is in the range of 900 ℃ ~ 1150 ℃. The method of claim 6, The cooling step is a method of joining titanium carbide alloy steel and steel, characterized in that the step of quenching. Titanium carbide alloy steel and steel joined body produced by the method of claim 6. Charging tungsten carbide-cobalt alloy (WC-Co), tungsten carbide-nickel alloy (WC-Ni), and steel into the can in turn; Heat-treating the charged materials by hot hydrostatic molding; And Cooling the heat treated materials; Bonding method of tungsten carbide-cobalt alloy and steel, characterized in that consisting of. The method of claim 18, The tungsten carbide-cobalt alloy (WC-Co) is in the form of a bulk (bulk), tungsten carbide-nickel alloy (WC-Ni) is a joining method of the tungsten carbide-cobalt alloy and steel, characterized in that the powder form. The method of claim 18, The steel is a method of bonding tungsten carbide-cobalt alloy and steel, characterized in that at least one selected from SUS420J2, S45C, SKD61. The method of claim 18, The tungsten carbide-cobalt alloy (WC-Co), the tungsten carbide-nickel alloy (WC-Ni), and SKD61 is inserted into the can in order to join the tungsten carbide-cobalt alloy and steel. The method of claim 18, The method of joining tungsten carbide-cobalt alloy and steel, characterized in that the heat treatment temperature during the heat treatment by hot water synthesis molding is 1200 ℃ ~ 1400 ℃, heat treatment pressure is 12000psi ~ 17000psi. The method of claim 18 or 22, The heat treatment step further comprises the step of maintaining for 1 to 4 hours at the corresponding temperature tungsten carbide-cobalt alloy and the joining method of the steel. The method of claim 18, The cooling of the heat-treated material is a bonding method of tungsten carbide-cobalt alloy and steel, characterized in that cooling to room temperature. The method of claim 18, The cooling step is a tungsten carbide-cobalt alloy and steel joining method characterized in that the slow cooling step. The method of claim 25, The slow cooling step is a method of bonding tungsten carbide-cobalt alloy and steel, characterized in that the cooling to 5 ℃ / hr conditions. The method of claim 18, The tungsten carbide-cobalt alloy has an alloy ratio in the range of 9: 1 to 7: 3, and the tungsten carbide-nickel alloy has an alloy ratio in the range of 4: 6 to 6: 4. Joining method of carbide-cobalt alloy and steel. A joint of tungsten carbide-cobalt alloy and steel produced by the method according to claim 18.

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