JP7659826B2 - Manufacturing method for bonded metal parts - Google Patents

Description

The present invention relates to a method for manufacturing a bonded metal part by bonding a bonding member formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member to a cemented carbide member formed of a cemented carbide.

Regarding the improvement of the properties of cemented carbide tools used as cutting tools, it has been reported in recent years in Patent Document 1 that by removing the metallic bonding phase from the tool surface of cemented carbide alloys consisting of a hard particle phase and a metallic bonding phase and using the tool with only the hard particle phase remaining on the surface, the properties such as wear resistance and adhesion resistance can be improved.

Chemical etching and physical etching are used to remove this metallic bonding phase. For example, Patent Document 2 discloses a process for removing the surface metallic bonding phase using aqua regia or nitric acid solution.

WO2019/065677 publication JP 2019-206754 A

When the processes described in Patent Documents 1 and 2 are applied to a bonded metal part manufactured by bonding a bonding member formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide component to a cemented carbide component, a situation occurs in which, due to the difference in ionization tendency, only the bonding member formed of the alloy having a parent phase of a metal with a higher ionization tendency is etched, and the corrosion of the metallic bonding phase of the cemented carbide constituting the cemented carbide component does not progress.

For example, in a metal wire drawing process, in a composite die in which an iron alloy used as an outer diameter retaining ring is joined to an inner diameter cemented carbide die, when attempting to etch the inner diameter cemented carbide, due to the difference in ionization tendency, only the outer diameter iron alloy ring is etched, and corrosion of the metallic bonding phase in the inner diameter cemented carbide does not progress.

Under such circumstances, corrosion of the metal bonding phase of the cemented carbide cannot be carried out as intended, and it is not possible to achieve improved properties such as wear resistance and adhesion resistance for bonded metal parts that include cemented carbide members as components.

The present invention has been made to solve these problems, and aims to provide a method for manufacturing a bonded metal part that can cause corrosion of the metal bonding phase of the cemented carbide as intended, and can improve properties such as wear resistance and adhesion resistance, even in a bonded metal part manufactured by bonding a bonding member formed of an alloy whose parent phase is a metal that has a higher ionization tendency than the parent phase of the metal bonding phase of the cemented carbide that constitutes the cemented carbide member, to a cemented carbide member formed of the cemented carbide.

In order to solve the above problems, the present invention provides a method for manufacturing a bonded metal part by bonding a bonding member formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide part to a cemented carbide part formed of a cemented carbide, and the method for manufacturing a bonded metal part is characterized in that the bonding member is coated with a non-eluting material, and then, of the hard particle phase and metallic bonding phase contained in the cemented carbide constituting the cemented carbide part, only the metallic bonding phase is selectively etched and surface-treated.

By coating a joining member made of an alloy whose parent phase is a metal with a higher ionization tendency than the parent phase of the metallic bond phase of the cemented carbide constituting the cemented carbide member with a non-eluting material and then selectively etching only the metallic bond phase of the hard particle phase and metallic bond phase contained in the cemented carbide constituting the cemented carbide member to perform surface treatment, it is possible to prevent a situation in which only the joining member made of an alloy whose parent phase is a metal with a higher ionization tendency is etched and the metallic bond phase of the cemented carbide constituting the cemented carbide member does not corrode. This makes it possible to improve properties such as wear resistance and adhesion resistance.

In the present invention, the joining method of the joining member to the cemented carbide member can be material joining, chemical joining, or mechanical joining, and can be applied to various joining forms. Therefore, it can be applied to joining type metal parts such as dies and tools for various uses and shapes. Here, material joining is joining that utilizes the characteristics of metal materials, such as welding, brazing, and friction stir welding. Chemical joining is joining that uses adhesives, etc. Mechanical joining is joining by fixing with screws, rivets, etc., or by fitting with press fitting, shrink fitting, etc.

In the present invention, the depletion depth of the metallic bonding phase when only the metallic bonding phase is selectively etched can be calculated from four pieces of information: the composition of the cemented carbide base material, the composition measured by characteristic X-ray analysis from the top surface after the cemented carbide base material is processed into a bonded metal part and the metallic bonding phase is selectively etched, the composition of the metallic bonding phase remaining slightly between the hard particles in the depleted region of the selectively etched metallic bonding phase, and the analysis depth measured by the emission of characteristic X-rays in the characteristic X-ray analysis.

As a result, a small amount of metallic bond phase remains between the hard particles in the depletion layer after selective etching, and the amount of metallic bond phase that changes smoothly at the interface can be efficiently calculated. Therefore, when a joining member formed of an alloy whose parent phase is a metal with a higher ionization tendency than the parent phase of the metallic bond phase of the cemented carbide constituting the cemented carbide member is coated with a non-eluting material and then surface treatment is performed by selectively etching only the metallic bond phase out of the hard particle phase and metallic bond phase contained in the cemented carbide constituting the cemented carbide member, it becomes possible to accurately calculate the corrosion depth non-destructively. Note that the selective corrosion depth is assumed to be approximately the same as the average grain size of the hard particles from the viewpoint of strength retention.

According to the present invention, even in the case of a bonded metal part manufactured by bonding a bonding member formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member, it is possible to realize a manufacturing method of a bonded metal part that can cause corrosion of the metallic bonding phase of the cemented carbide as intended, thereby realizing improved properties such as wear resistance and adhesion resistance.

FIG. 1 is a schematic diagram of a shrink-fitted powder compaction die. FIG. 13 is a diagram showing the change in a powder molding die before and after etching. FIG. 1 is a schematic diagram of a brazed bonded metal part. FIG. 1 is a diagram showing the change in a bonded metal component before and after etching. FIG. 2 is a schematic diagram showing a cross section of a metallic bonding phase on a surface of a cemented carbide member after selective etching and a change in the amount of _CO, which is a main component of the metallic bonding phase, during the selective etching. FIG. 2 is a diagram for defining the depletion depth of a metallic bonding phase. 1 is a flow chart of a method for measuring the depletion depth of a surface metal binder phase in a cemented carbide.

Hereinafter, a method for producing a bonded metal component according to the present invention will be described based on an embodiment thereof.
A first embodiment of a method for manufacturing a bonded metal component will be described with reference to FIG.
FIG. 1 is a schematic diagram of a shrink-fitted powder compaction die.
The powder molding die is an example of a bonded metal part manufactured by bonding a cemented carbide member 3 formed of a cemented carbide to a bonding member 4 formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member 3, and material type G3 (classification symbol VM-40) is used for the cemented carbide member 3, and SKD11 is used for the bonding member 4. In cemented carbide, cobalt or nickel is generally used for the metallic bonding phase, and cobalt is selected for the parent phase of the metallic bonding phase of material type G3 of the cemented carbide member 3.

For the powder molding die having this configuration, the joining members 4 were covered with a non-eluting material, and then surface treatment was performed by selectively etching only the metallic bonding phase out of the hard particle phase and metallic bonding phase contained in the cemented carbide constituting the cemented carbide member 3. For comparison, etching treatment was also performed without covering the joining members 4 with a non-eluting material. After the etching treatment, the appearance change was observed, and the change in the metallic bonding phase was analyzed by SEM-EDS.
Table 1 shows the results of SEM-EDS analysis of the cemented carbide parts using an SU3800 electron microscope.

The results shown in Table 1 show that with etching without a coating, the amount of cobalt in the metallic bonding phase remains unchanged compared to before etching, indicating that no reaction has occurred. In contrast, with etching with a coating, the amount of cobalt in the metallic bonding phase is clearly less than before etching, indicating that corrosion of the metallic bonding phase is progressing.

Figure 2 shows the changes in the powder molding die before and after etching. Figure 2(a) shows the powder molding die before etching, Figure 2(b) shows the powder molding die after etching without being coated with a non-eluting material, and Figure 2(c) shows the powder molding die after etching with a coating of a non-eluting material.

Comparing Figure 2(a) and Figure 2(b), in Figure 2(b), the outer parts, which are the joined metal part materials, have turned black, indicating that they have been corroded by the etching solution. In contrast, in Figure 2(c), there is no discoloration in the outer parts, which are the joined metal part materials, indicating that they have not been corroded by the etching solution.

The above results demonstrate that in a bonded metal part manufactured by bonding a bonding member 4 formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member 3 formed of cemented carbide, it is possible to suppress corrosion of the bonding member 4 and to cause corrosion of the metallic bonding phase of the cemented carbide of the cemented carbide member 3 as intended.

A second embodiment of the method for producing a bonded metal component will be described with reference to FIG.
FIG. 3 is a schematic diagram of a brazed bonded metal part.
This brazed bonded metal part is an example of a bonded metal part manufactured by bonding a bonding member 4 formed of an alloy having a parent phase of a metal that has a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide part 3 to a cemented carbide part 3 formed of a cemented carbide. The cemented carbide part 3 is made of material type G5C (classification symbol VM-50), and the bonding member 4 is made of steel material S45C.

For the bonded metal part having this configuration, the bonding members 4 were coated with a non-eluting material, and then surface treatment was performed by selectively etching only the metallic bonding phase out of the hard particle phase and metallic bonding phase contained in the cemented carbide constituting the cemented carbide member 4. For comparison, etching treatment was also performed without coating the bonding members 4 with a non-eluting material. After the etching treatment, the appearance change was observed, and the change in the metallic bonding phase was analyzed by SEM-EDS.
Table 2 shows the results of SEM-EDS analysis of the cemented carbide parts using an SU3800 electron microscope.

The results shown in Table 2 show that with etching without a coating, the amount of cobalt in the metallic bonding phase remains unchanged compared to before etching, indicating that no reaction has occurred. In contrast, with etching with a coating, the amount of cobalt in the metallic bonding phase is clearly less than before etching, indicating that corrosion of the metallic bonding phase has progressed.

Figure 4 shows the changes in a bonded metal part before and after etching. Figure 4(a) is a bonded metal part before etching, Figure 4(b) is a bonded metal part after etching without being coated with a non-eluting material, and Figure 4(c) is a bonded metal part after etching with a coating of a non-eluting material.

Comparing Figure 4(a) and Figure 4(b), in Figure 4(b), the joined metal component material has turned black, indicating that it has been corroded by the etching solution. In contrast, in Figure 4(c), there is no discoloration of the joined metal component material, indicating that it has not been corroded by the etching solution.

The above results demonstrate that in a bonded metal part manufactured by bonding a bonding member 4 formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member 3 to a cemented carbide member 3, it is possible to suppress corrosion of the bonding member 4 and to cause corrosion of the metallic bonding phase of the cemented carbide of the cemented carbide member 3 as intended.

As described above, the effectiveness of the method has been demonstrated in bonded metal parts manufactured by bonding a bonding member 4 made of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide member 3 to a bonded metal part having a different bonding method and shape. The bonding method of the bonding member 4 to the cemented carbide member 3 can be material bonding, chemical bonding, or mechanical bonding, and can be applied to various bonding forms. Therefore, it can be widely applied to bonded metal parts having different bonding methods and shapes, such as composite dies, composite punches, composite molds, etc.

The following describes a method for calculating the depletion depth of the selective corrosion of the metallic bonding phase when corroding the metallic bonding phase of a cemented carbide in the manufacturing method of the bonded metal part of the present invention.

5 is a schematic diagram showing a cross section of the surface of a cemented carbide member after selective etching of the metallic bonding phase and the change in the amount of _CO, the main component of the metallic bonding phase, during the selective etching. In the depletion layer after selective etching, a small amount of metallic bonding phase 2 remains between the hard particles 1, so the amount of _CO fluctuates and does not become completely zero. A gradual transition in the amount of _CO occurs from the region where the metallic bonding phase 2 has been removed by corrosion to the unreacted region, and it is necessary to define the depletion depth in this region.

Therefore, the inventors have decided to define the depletion depth of the metallic bonding phase by assuming a linear change in components as shown in Fig. 6. The amount of _CO in the matrix is m1, and the small amount of _CO remaining between the hard particles is m2. It is assumed that m2 and m1 are both constant values, and that the transition from m2 to m1 occurs linearly as shown in Fig. 6.

The transition position of the _CO amount where this linear change occurs is defined as the depletion depth d of the metallic bonding phase. Using these definitions, the analysis depth D measured by the X-rays irradiated in the characteristic X-ray analysis, and the amount of Co mx actually measured by the characteristic X-ray analysis, an equation is created based on the conservation of mass of the amount of Co, and the following equation (1) is obtained.

By solving equation (1) with respect to the deficiency depth d, we obtain equation (2).

Here, the concentration of the metallic bonding phase remaining between the hard particles must be estimated in advance using an analysis method attached to the scanning electron microscope. The analysis depth is determined by the X-ray intensity of the characteristic X-ray analyzer used and the composition of the cemented carbide being analyzed.

Characteristic X-ray analyzers include energy dispersive X-ray analyzers (EDS) and wavelength dispersive X-ray analyzers (WDS). Both instruments measure the chemical composition of a sample by detecting characteristic X-rays emitted from the sample surface, with EDS measuring the energy of characteristic X-rays and WDS measuring the wavelength of characteristic X-rays.

In EDS, the reaction region of characteristic X-rays is relatively shallow at a depth of a few μm, while WDS has an analysis depth of more than 10 μm. In the present invention, considering that the material to be analyzed has hard particle diameters of about a few μm, it can be said that a wavelength dispersive characteristic X-ray analyzer (WDS), which can measure the depth of multiple particles, is a more desirable analytical device.

Although this is a simplified definition of the deficiency depth, it is arithmetically uniquely determined and always intersects with the transition region of the Co content, making it a very easy definition to use when specifying it as an agreement in specifications. Furthermore, because this measurement method is non-destructive, it can be used directly for shipping inspections, and at the same time, it can also be used to analyze the cause of abnormalities.

As described above, it is possible to calculate the depletion depth d of the metallic bonding phase from four pieces of information: the composition m1 of the cemented carbide base material, the composition mx measured from the top surface by characteristic X-ray analysis after processing the same base material into a bonded metal part and selectively etching the metallic bonding phase, the composition m2 of the metallic bonding phase remaining slightly between the hard particles in the depleted area of the selectively etched metallic bonding phase, and the analysis depth D measured by the emission of characteristic X-rays in the characteristic X-ray analysis.

Figure 7 shows a flowchart of the method for measuring the depletion depth of the surface metallic bonding phase in a cemented carbide, as explained above. By carrying out this process, when the metallic bonding phase of a cemented carbide is removed from the surface by etching, the metallic bonding phase leaves the hard particle phase in a mesh-like shape, and selective corrosion progresses in a tunnel-like shape. Even in this situation, the calculated corrosion depth can non-destructively and unambiguously define the depth of the corrosion front, whose boundary is actually ambiguous.

A comparison test between the calculated and measured values of the above-mentioned defect depth was carried out for three material types with different particle sizes (fine, medium, and coarse), by producing samples for each of the fine, medium, and coarse grains. The average particle size of each was 0.6 to 1.0 μm for fine grains, 2.0 to 4.0 μm for medium grains, and 5.0 μm or more for coarse grains. The actual measurements were taken at several locations using a wavelength dispersive X-ray analyzer (WDS) and an energy dispersive X-ray analyzer (EDS), and the average values were calculated.

As a result of the test, the difference between the calculated and measured deficiency depths was much smaller than half the particle diameter of the hard particles for all the cases of fine, medium, and coarse grains. The value of half the particle diameter of the hard particles can be recognized as a boundary value that determines whether or not the hard particles will fall off, and if the difference between the calculated and measured deficiency depths exceeds half the particle diameter of the hard particles, it will have a negative effect on the function of the parts made of cemented carbide when selective corrosion is performed. However, according to the test results, the difference between the calculated deficiency depth and the measured value was much smaller than half the particle diameter of the hard particles, so it was confirmed that the method of calculating the calculated deficiency depth according to the present invention is extremely effective.

By using this method, it is possible to accurately calculate the corrosion depth nondestructively when a joining member formed of an alloy whose parent phase is a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide that constitutes the cemented carbide component is coated with a non-eluting material and then surface treated by selectively etching only the metallic bonding phase out of the hard particle phase and metallic bonding phase contained in the cemented carbide that constitutes the cemented carbide component.

The present invention can be widely used as a manufacturing method for bonded metal parts that can improve properties such as wear resistance and adhesion resistance because it is possible to intentionally corrode the metallic bonding phase of the cemented carbide even in bonded metal parts manufactured by bonding a bonding member formed of an alloy having a parent phase of a metal that has a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide that constitutes the cemented carbide member to a cemented carbide member.

Reference Signs List 1 Hard particles 2 Metallic bonding phase 3 Cemented carbide member 4 Joining member

Claims (2)

A method for manufacturing a bonded metal part by bonding a bonding member formed of an alloy having a parent phase of a metal with a higher ionization tendency than the parent phase of the metallic bonding phase of the cemented carbide constituting the cemented carbide part to a cemented carbide part formed of a cemented carbide, the method being characterized in that the bonding member is coated with a non-eluting material, and then the metallic bonding phase alone of the hard particle phase and metallic bonding phase contained in the cemented carbide constituting the cemented carbide part is selectively etched and surface-treated. The method for manufacturing a bonded metal part according to claim 1, characterized in that the bonding method of the bonding member to the cemented carbide member is by material bonding, chemical bonding, or mechanical bonding.

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