Process for realizing diffusion bonding of dissimilar materials through powder metallurgy process

Abstract

The invention relates to the technical field of metal heat treatment, in particular to a process for realizing diffusion bonding of dissimilar materials through a powder metallurgy process, which comprises the following steps of: controlling the mechanical property, the dimensional accuracy, the surface appearance and the structural integrity of a formed blank through selection of alloy elements, regulation and control of component proportion and optimization of additive components and content; the wear-resistant material powder is pressed into a blank, then the sintering temperature, the sintering time, the sintering pressure and other parameters are used for control, blank forming is achieved, the bonding strength of the blank and parts is improved, a steel-based typical structural part with local high wear resistance is manufactured, the strength and wear resistance of the mechanical parts are greatly improved, and the service life of the mechanical parts is greatly prolonged. The dissimilar material connecting process is suitable for engineering forming design and preparation production of locally-reinforced wear-resistant structural parts such as mining machinery, oil and gas pipelines, ocean platforms and bridge structures.

Description

Technical Field

[0001] The invention relates to a processing technology for wear-resistant parts of low-alloy steel with high wear resistance, high strength and high toughness, belonging to the technical field of dissimilar material connection, and specifically to a process for realizing diffusion connection of dissimilar materials through a powder metallurgy process. Background Art

[0002] In the fields of engineering machinery, mining machinery, etc., the hardness and load-bearing capacity of parts used to withstand impact loads directly affect the service life of the parts. Take the rotary drilling rig used for hole-forming operations in building foundation engineering as an example. The arc plate and reinforcement ring of the rotary drilling drill rod are located on each section of the machine lock rod drill rod, and bear the pressure and torque of the drilling rig. Therefore, as key load-bearing parts, the arc plate and drill rod reinforcement ring need to have high tensile strength, wear resistance and impact resistance. At present, high-quality arc plates and reinforcement rings usually adopt diffusion bonding technology, which closely contacts the welding surfaces of two or more parts to be connected under certain temperature, time and pressure conditions, so that atoms diffuse on the surfaces of the two parts to form a transition layer, thereby forming a strong bond at their contact interface to increase the local wear resistance of the parts, which can not only meet service requirements but also save costs; however, traditional diffusion bonding often only connects one surface, that is, the connection between the plates, with a small contact area and weak shear and impact resistance. In construction operations in rock layers with extremely harsh working conditions, the drill rod is subjected to the dual effects of pressure and impact during operation. Parts falling off, cracking, curling, and non-wear resistance become the main failure points of drill rod accidents. Therefore, improving the local wear resistance and impact resistance of parts and achieving close bonding of various components have become technical problems that need to be urgently solved by domestic rotary drilling rig suppliers. Summary of the invention

[0003] In view of the above problems, the present invention provides a process for achieving diffusion connection of dissimilar materials through powder metallurgy process, which can simply and efficiently manufacture high-strength and high-impact mechanical structural parts with locally enhanced wear resistance.

[0004] The purpose of the present invention is achieved through the following technical solutions: A process for achieving diffusion connection of dissimilar materials by powder metallurgy process, using ball milling-cold pressing method to prepare high-performance wear-resistant material molded blanks with specific shapes, and using powder metallurgy forming technology to prepare steel structural parts with local reinforcement of wear-resistant materials; comprising the following steps: 1. Production of molded blanks: ①. High performance wear-resistant material composition, alloy powder includes by mass percentage: C: 0.15-0.45%, Cr: 0.5-2.5%, Si: 0.3-1.0%, Mn: 0.5-1.5%, Mo: 0-1.0%, Ni: 0.5-2.5%, the balance is Fe, and there are a small amount of inevitable trace impurities; ②. Powder preparation: weigh the alloy powder according to the proportion under vacuum conditions, and add 0.6-1.5% of the total weight of dispersant and lubricant; ③.Ball milling: ball mill the prepared powder to mix it for mechanical alloying; ④. Pressing: The ball-milled mixed powder is pressed in a cold pressing mold at a pressure of 600-900 MPa for 60-300 seconds to form a wear-resistant molded blank of a specific shape; 2. Machining of steel base parts: The installation grooves matching the molded blank are machined on the wear-resistant parts of the steel base, and the connection surfaces between the steel base and the molded blank are mechanically polished; 3. Assembly: The molded blank and the steel base are assembled through the mounting groove to form a steel base structural part. The steel base structural part is fixed on the diffusion bonding furnace by using a graphite mold. The furnace door is closed to evacuate the furnace, and a pressure of 1 to 5 MPa is applied to the graphite punch to press the molded blank and the steel base tightly. 4. Sintering forming: When the vacuum degree reaches -0.1 MPa, first heat to 250-300°C at a rate of 6°C / min, and keep at this temperature for 60 minutes; continue to heat to 750-900°C at a rate of 6°C / min, and keep at this temperature for 60 minutes; then heat to 1100-1300°C at a rate of 4°C / min; after reaching the temperature, operate the diffusion bonding furnace to apply a pressure of 30-60MPa to the graphite punch, keep warm and pressure for 60-90 minutes, unload the pressure after sintering, and allow the steel-based structural parts to cool to room temperature in the diffusion bonding furnace.

[0005] Furthermore, the particle size of the alloy powder in step 1① is ≤74 μm.

[0006] Furthermore, the dispersant and lubricant in step 1② are zinc stearate and / or vinyl bisstearamide.

[0007] Furthermore, in step 1③, anhydrous ethanol accounting for one third of the total weight of the alloy powder is added to fully disperse and mix the alloy powder evenly. After ball milling, the powder is dried in a vacuum drying oven, and the agglomerated powder after drying is ground in a mortar under a vacuum environment.

[0008] Furthermore, in step 1③, a planetary ball mill is used for mechanical mixing, using zirconium oxide ball milling beads with sizes of 10 mm, 6 mm and 2 mm, a rotation speed of 100-150 r / min, a ball milling time of 6-48 h, and a 5-min stop after every 30 min of ball milling.

[0009] Furthermore, the alloy powder in step 1① also includes a ceramic powder additive, and the ceramic powder additive accounts for 0.25 to 6% of the total weight.

[0010] Furthermore, in the step 2, the surface roughness of the connection between the steel base member and the molded blank is less than Ra6.3.

[0011] The beneficial effects of the present invention are: The present invention utilizes powder metallurgy technology to realize high-performance powder sintering and integrated forming of typical parts diffusion connection, and prepares typical structural parts with locally enhanced wear resistance, which is suitable for engineering forming design and preparation production of locally enhanced wear-resistant structural parts such as mining machinery, oil and gas pipelines, offshore platforms, bridge structures, etc. The present invention controls the mechanical properties, dimensional accuracy, surface morphology, and structural integrity of the formed blank by selecting alloy elements, regulating the proportion of components, and optimizing the composition and content of additives; and then utilizes the control of parameters such as sintering temperature, sintering time, and sintering pressure to realize blank forming and increase the bonding strength between the blank and the parts, so as to make a typical steel-based structural part with local high wear resistance, and greatly improve the strength, wear resistance and performance of mechanical parts. Compared with the prior art, the present invention ensures the basic shape of the wear-resistant area through the preparation of high-performance wear-resistant powder pressing and forming, thereby improving the local wear resistance of parts. On the other hand, the integrated forming process of wear-resistant blank sintering and parts high-temperature diffusion connection not only realizes the precise forming of wear-resistant materials, but also ensures the close combination of wear-resistant materials and parts, increases the bonding area between the two, and enhances the performance of typical parts.

[0012] In addition, the integrated forming process of sintering the molded blank and high-temperature diffusion bonding of parts reduces the preparation process, shortens the production time, and improves the material utilization rate and the performance and service life of the structural parts.

[0013] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Flow chart for powder metallurgy process to realize diffusion bonding of dissimilar materials.

[0015] Figure 2 Schematic diagram of the mold for realizing diffusion bonding of dissimilar materials by powder metallurgy process; DETAILED DESCRIPTION

[0016] In the figure: 1-graphite punch, 2-graphite jacket, 3-molded blank, 4-steel base. Example 1

[0017] The present invention discloses a process for achieving diffusion connection of dissimilar materials through powder metallurgy process. The mechanical properties, dimensional accuracy, surface morphology and structural integrity of the formed blank are controlled by selecting alloy elements, regulating the proportion of components, optimizing the composition and content of additives. Wear-resistant material powder is pressed into blanks. Then, parameters such as sintering temperature, sintering time and sintering pressure are controlled to achieve blank forming and increase the bonding strength between the blank and parts, so as to prepare typical steel-based structural parts with local high wear resistance.

[0018] This embodiment takes the preparation of a rotary drilling drill rod reinforcement ring as an example to explain the technical solution of the present invention in detail: A rotary drilling rig is a construction machine used for drilling operations in building foundation projects, especially in rock layer construction, where the working conditions are very harsh. Components such as the drill pipe reinforcement ring and arc plate of the rotary drilling rig are located on each section of the drill pipe of the machine lock rod. They bear the pressure and torque of the drilling rig during the drilling operation. They are the key parts of the rotary drilling rig. Their hardness and bearing capacity directly affect their service life. Therefore, the drill pipe reinforcement ring, arc plate and other parts need to have high tensile strength, wear resistance and impact resistance.

[0019] The drill pipe reinforcement ring of the rotary drilling rig is prepared by using the integrated forming process of high-performance wear-resistant blank sintering and parts high-temperature diffusion connection; Figure 1 As shown in the process flow chart, high-performance wear-resistant powder is first pressed into a blank by cold pressing to ensure the local specific shape that needs to enhance wear resistance. The blank is then sintered into a wear-resistant material and connected to the steel part through an integrated forming process of powder metallurgy and diffusion bonding to obtain a typical steel-based structural part with locally enhanced wear-resistant material with high dimensional accuracy and good wear resistance.

[0020] The specific implementation is as follows: 1. Production of high-performance wear-resistant die-pressed blanks: ①. High performance wear-resistant material, alloy powder includes the following components by mass percentage: C: 0.20%, Cr: 0.6%, Si: 0.6%, Mn: 1.3%, Mo: 0.2%, Ni: 1.0%, the balance is Fe, and there are a small amount of inevitable trace impurities; the original powder particle size is ≤74μm (within 200 mesh); ② Powder preparation: weigh the powders in proportion under vacuum conditions, and add 0.6wt.% of the total weight of zinc stearate as a dispersant and lubricant; ③. Ball milling: add one third of the total weight of the powder to the powder prepared in step ②, so that the powder is fully dispersed and mixed evenly, and mechanically mixed on a planetary ball mill, using zirconium oxide ball milling beads with sizes of 10 mm, 6 mm and 2 mm, a speed of 150 r / min, a ball milling time of 48 h, and a stop time of 5 min every 30 min of ball milling; after the ball milling, separate the mixed powder from the ball milling beads, dry the anhydrous ethanol in a vacuum drying oven, and grind the blocks produced during the drying process in a vacuum environment with a mortar to obtain an alloyed powder; ④. Pressing blanks: The alloyed powder mixed in step ③ is pressed into shape on a press. The inner wall of the cold pressing mold is lubricated with polytetrafluoroethylene before pressing. The pressing pressure is 600MPa and the pressure is maintained for 300s to press into a wear-resistant material molded blank of a specific shape.

[0021] 2. Machining of steel base parts: The steel base parts are processed and, according to the use requirements of the parts and the shape of the molded blanks, mounting slots that cooperate with the molded blanks are processed at the connection between the steel base parts and the molded blanks (i.e. the wear-resistant parts of the parts), such as cylindrical, rectangular, T-shaped and dovetail shapes; then the surface of the connection between the steel base parts and the molded blanks is precisely polished to make the surface roughness less than Ra 6.3.

[0022] 3. Assembly: According to the size and use requirements of the drill pipe reinforcement ring, a powder sintering and diffusion bonding integrated forming graphite mold is designed and prepared. The molded blank is embedded in the steel base installation groove to form a steel base structure, and then placed in the graphite mold. Figure 2 As shown, boron nitride is sprayed on the mold surface as a release agent; the steel-based structural part is fixed on the diffusion bonding furnace using a graphite mold, the furnace door is closed and evacuated to a vacuum degree of -0.1 MPa, and a pressure of 3 MPa is applied to the graphite punch to make the molded blank fit tightly with the steel base part.

[0023] 4. Sintering forming: When the vacuum degree in the furnace reaches -0.1MPa, the temperature begins to rise. First, it is heated to 300℃ at a rate of 6℃ / min, and kept at this temperature for 60min to pre-discharge the additives; it is continued to be heated to 800℃ at a rate of 6℃ / min, and kept at this temperature for 60min to finally discharge the additives; then it is heated to 1100-1300℃ at a rate of 4℃ / min; after reaching the temperature, the diffusion bonding furnace is operated to slowly apply a pressure of 45MPa to the graphite punch, and the temperature and pressure are kept for 60-90min. After sintering, the pressure is unloaded to allow the parts to slowly cool to room temperature in the diffusion bonding furnace.

[0024] The present invention uses a high-performance wear-resistant blank sintering forming and a high-temperature diffusion connection forming process for parts to make atomic diffusion occur on the surface of two or more connecting parts, forming a transition layer, thereby forming a strong bond at the contact interface, and realizing the connection between dissimilar materials with large performance differences. Its principle is to prepare a local structural blank with enhanced wear resistance through a mechanical alloying process, and to use a powder metallurgy process to realize the integrated forming of high-performance powder sintering forming and typical parts diffusion connection, so as to prepare a typical steel-based structural part with locally enhanced wear resistance. In the process of high-performance wear-resistant material powder pressing into blanks, the mechanical properties, dimensional accuracy, surface morphology, and structural integrity of the formed blanks are mainly controlled by the selection of alloy elements, the regulation of component ratios, and the optimization of additive components and contents; in the process of high-performance wear-resistant blank forming and parts diffusion connection forming, parameters such as sintering temperature, sintering time, and sintering pressure are used to realize blank forming and increase the bonding strength between blanks and parts, thereby improving the strength, wear resistance, and performance of parts such as mining machinery and bridge structures.

[0025] On the one hand, the integrated forming process of the present invention ensures the basic shape of the wear-resistant area through powder pressing, thereby improving the local wear-resistant effect of the parts; on the other hand, the integrated forming process of wear-resistant blank sintering forming and high-temperature diffusion connection of parts realizes the forming of wear-resistant materials and the close combination with steel-based parts, increases the bonding area between the two, optimizes the use performance of typical parts, and solves the current problem of enhancing the local wear resistance of typical parts in the fields of bridges, high-rise buildings, oil and gas pipelines, mining machinery, ships and offshore platforms. At the same time, it greatly saves materials, reduces preparation processes, shortens preparation production time, and improves production efficiency. Example 2

[0026] This embodiment takes the production of circular arc plates of rotary drilling pipes as an example. It is required that the parts can be welded and the non-welded parts have excellent wear resistance. According to the performance requirements of the parts, ceramic particles can be added to the alloy powder as additives, such as TiB2, SiC, Al2O3, ZrO2, etc., to further improve the local wear resistance of the structural parts.

[0027] 1. Production of molded blanks: ①. High performance wear-resistant material composition, alloy powder includes by mass percentage: C: 0.35%, Cr: 1.0%, Si: 0.7%, Mn: 1.0%, Mo: 0.5%, Ni: 1.3%, TiB2: 0.3%, the balance is Fe, and there are a small amount of inevitable trace impurities; alloy powder particle size ≤ 74μm; ②. Powder preparation: weigh the powders in proportion under vacuum conditions, and add 0.6-1.5 wt.% of the total weight of zinc stearate or vinyl bisstearamide as a dispersant and lubricant; ③. Ball milling: The powder prepared in step ② was mechanically mixed in a planetary ball mill, using zirconium oxide ball milling beads with sizes of 10 mm, 6 mm and 2 mm, respectively, at a speed of 100 r / min, a ball milling time of 20 h, and a 5-min stop for each 30 min of ball milling; during the ball milling process, anhydrous ethanol was added in an amount of one-third of the total weight of the alloy powder to fully disperse the powder and mix it evenly. After the ball milling, the mixed powder was separated from the ball milling beads, the anhydrous ethanol was dried in a vacuum drying oven, and the blocks produced during the drying process were ground with a mortar under a vacuum environment to obtain an alloyed powder; ④. Pressing: The ball-milled mixed powder is pressed into a wear-resistant molded blank of a specific shape in a cold pressing mold at a pressure of 700 MPa for 270 seconds.

[0028] 2. Machining of steel base parts: Use low carbon steel to process steel base parts, process installation grooves that match the molded blanks in the wear-resistant parts of the steel base parts, and mechanically grind the connecting surfaces of the steel base parts and the molded blanks to make the surface roughness of the connecting surfaces less than Ra 6.3.

[0029] 3. Assembly: The molded blank and the steel base are assembled to form a steel-based structural part. The steel-based structural part is fixed on the diffusion bonding furnace using a graphite mold. The furnace door is closed to evacuate the furnace, and a pressure of 2.2 MPa is applied to the graphite punch to press the molded blank and the steel base.

[0030] 4. Sintering: When the vacuum reaches -0.1 MPa, first heat to 280℃ at a rate of 6℃ / min and keep it at this temperature for 60min; continue to heat to 850℃ at a rate of 6℃ / min and keep it at this temperature for 60min; then heat to 1100℃ at a rate of 4℃ / min; after reaching the temperature, operate the diffusion bonding furnace to apply 35MPa pressure to the graphite punch, keep it warm and pressurized for 70min, unload the pressure after sintering, and let the steel-based structural parts slowly cool to room temperature in the diffusion bonding furnace. The obtained arc plate steel-based low-carbon steel matrix has excellent welding performance. After heat treatment, the hardness of the molded blank can reach HV730, the tensile strength is 1750MPa, and the elongation is 16.5%, so that it can maintain weldability and enhance its wear resistance. Example 3

[0031] This embodiment takes the preparation of a rotary drill key sleeve body and key strip as an example. The key sleeve body and key strip are torque transmission parts, which are required to have excellent comprehensive performance and high wear resistance and high impact resistance.

[0032] 1. Production of molded blanks: ①. High performance wear-resistant material composition, alloy powder includes by mass percentage: C: 0.4%, Cr: 1.8%, Si: 0.8%, Mn: 1.5%, Mo: 0.8%, Ni: 2.0%, TiB2: 0.45%, the balance is Fe, and there are a small amount of inevitable trace impurities; the original particle size of the powder is ≤74μm; ②. Powder preparation: weigh the powders in proportion under vacuum conditions, and add 0.6-1.5 wt.% of the total weight of zinc stearate or vinyl bisstearamide as a dispersant and lubricant; ③. Ball milling: The powder prepared in step ② was mechanically mixed in a planetary ball mill, using zirconium oxide ball milling beads with sizes of 10 mm, 6 mm and 2 mm, respectively, at a speed of 130 r / min, and the ball milling time was 30 h, and 5 min was stopped every 30 min of ball milling; during the ball milling process, anhydrous ethanol was added in an amount of one third of the total weight of the alloy powder to fully disperse the powder and mix it evenly. After the ball milling, the mixed powder was separated from the ball milling beads, the anhydrous ethanol was dried in a vacuum drying oven, and the blocks produced during the drying process were ground with a mortar under a vacuum environment to obtain an alloyed powder; ④. Pressing: The ball-milled mixed powder is pressed into a wear-resistant molded blank of a specific shape in a cold pressing mold at a pressure of 850MPa for 180s.

[0033] 2. Machining of steel base parts: 35CrMo or 42CrMo alloy steel is used as the steel base material, and a mounting groove matching the die-cast blank is machined on the steel base part. The connecting surface between the steel base part and the die-cast blank is mechanically polished to make the surface roughness of the connecting surface less than Ra 6.3.

[0034] 3. Assembly: Assemble the molded blank and the steel base part through the installation groove to form a steel-based structural part. Use a graphite mold to fix the steel-based structural part on the diffusion bonding furnace. Close the furnace door to evacuate the furnace, and apply a pressure of 5MPa to the graphite punch to press the molded blank and the steel base part tightly.

[0035] 4. Sintering: When the vacuum in the furnace reaches -0.1 MPa, first heat to 250℃ at a rate of 6℃ / min, and keep it at this temperature for 60min; continue to heat to 900℃ at a rate of 6℃ / min, and keep it at this temperature for 60min; then heat to 1200℃ at a rate of 4℃ / min; after reaching the temperature, operate the diffusion bonding furnace to apply 55MPa pressure to the graphite punch, and keep it warm and pressurized for 85min; after sintering, unload the pressure and let the steel-based structural parts slowly cool to room temperature in the diffusion bonding furnace. The obtained steel-based structural parts have excellent comprehensive mechanical properties of 35CrMo or 42CrMo alloy steel materials, and can withstand the extrusion load when transmitting torque; the hardness of the pressed blank after heat treatment can reach HV700, the tensile strength is 1600MPa, and the elongation is 16.5%, which keeps the key strip with high wear resistance and impact resistance when working.

[0036] Finally, it should be noted that the above embodiments are used to illustrate the technical solution of the present invention rather than to limit it. Technicians in the relevant field may modify the implementation methods or make equivalent substitutions for some technical features without departing from the essence of the technical solution of the present invention, and all of these should be included in the scope of protection required by the present invention.

Claims

1. A process for achieving diffusion bonding of dissimilar materials by powder metallurgy, characterized in that: The ball milling-cold pressing method is used to obtain a high-performance wear-resistant material blank with a specific shape. The powder metallurgy forming technology is used to achieve the sintering of the high-performance wear-resistant material and the diffusion connection with the matrix alloy to prepare a typical structural part with enhanced local wear resistance. The following steps are involved:

1. Production of molded blanks: ①. High performance wear-resistant material composition, alloy powder includes by mass percentage: C: 0.15-0.45%, Cr: 0.5-2.5%, Si: 0.3-1.0%, Mn: 0.5-1.5%, Mo: 0-1.0%, Ni: 0.5-2.5%, the balance is Fe, and there are a small amount of inevitable trace impurities; ②. Powder preparation: weigh the alloy powder according to the proportion under vacuum conditions, and add 0.6-1.5% of the total weight of dispersant and lubricant; ③.Ball milling: ball mill the prepared powder to mix it for mechanical alloying; ④. Pressing: The ball-milled mixed powder is pressed in a cold pressing mold at a pressure of 600-900 MPa for 60-300 seconds to form a wear-resistant molded blank of a specific shape; 2. Machining of steel base parts: The steel base is machined to form a mounting groove matching the die-pressed blank at the wear-resistant part of the steel base, and the connecting surface between the steel base and the die-pressed blank is mechanically polished; 3. Assembly: The molded blank and the steel base are assembled through the mounting groove to form a steel base structural part. The steel base structural part is fixed on the diffusion bonding furnace by using a graphite mold. The furnace door is closed to evacuate the furnace, and a pressure of 1 to 5 MPa is applied to the graphite punch to press the molded blank and the steel base tightly.

4. Sintering forming: When the vacuum degree reaches -0.1 MPa, first heat to 250-300°C at a rate of 6°C / min, and keep at this temperature for 60 minutes; continue to heat to 750-900°C at a rate of 6°C / min, and keep at this temperature for 60 minutes; then heat to 1100-1300°C at a rate of 4°C / min; after reaching the temperature, operate the diffusion bonding furnace to apply a pressure of 30-60MPa to the graphite punch, keep warm and pressure for 60-90 minutes, unload the pressure after sintering, and allow the steel-based structural parts to cool to room temperature in the diffusion bonding furnace.

2. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy according to claim 1, characterized in that: The alloy powder particle size in step 1① is ≤74 μm.

3. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy process according to claim 1, characterized in that: The dispersant and lubricant in step 1② are zinc stearate and / or vinyl bisstearamide.

4. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy according to claim 1, characterized in that: In step 1③, anhydrous ethanol accounting for one third of the total weight of the alloy powder is added to fully disperse and mix the alloy powder evenly. After ball milling, the powder is dried in a vacuum drying oven, and the agglomerated powder after drying is ground in a mortar under a vacuum environment.

5. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy process according to claim 1, characterized in that: In step 1③, a planetary ball mill is used for mechanical mixing, using zirconium oxide ball milling beads with sizes of 10 mm, 6 mm and 2 mm, a rotation speed of 100-150 r / min, a ball milling time of 6-48 h, and a 5-min stop after every 30 min of ball milling.

6. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy according to claim 1, characterized in that: The alloy powder in step 1① also includes a ceramic powder additive, and the ceramic powder additive accounts for 0.25-6% of the total weight.

7. The process for achieving diffusion bonding of dissimilar materials by powder metallurgy according to claim 1, characterized in that: In the step 2, the surface roughness of the connection between the steel base member and the molded blank is less than Ra6.3.

Images