CN104014922B - A kind of hard alloy and the quick diffusion welding method of steel - Google Patents

Abstract

The invention discloses a fast diffusion welding method of cemented carbide and steel. The method comprises the following steps: 1. Surface treatment is performed on the surface to be welded of the cemented carbide and the surface to be welded of the steel; The surface is treated for use; 3. The metal sheet is placed between the surface to be welded of the cemented carbide and the surface to be welded of the steel, and the whole workpiece is obtained; 4. The whole workpiece is subjected to pulse activation treatment and DC sintering treatment successively. , to obtain welded joints between cemented carbide and steel. The invention utilizes the pulse heating current to induce high-temperature plasma instantaneously in the microscopic area of the surface to be welded, cleans and activates the surface to be welded, and then uses the DC heating current to perform DC sintering treatment on the surface to be welded of the whole workpiece, thereby achieving high-temperature plasma in the extreme The rapid diffusion welding joint between cemented carbide and steel is obtained in a short period of time, which has the advantages of fast welding speed, low temperature, small applied pressure and high joint strength.

Description

A rapid diffusion welding method for cemented carbide and steel

technical field

The invention belongs to the technical field of dissimilar material welding, and in particular relates to a fast diffusion welding method of cemented carbide and steel.

Background technique

Cemented carbide is a cermet tool material prepared by powder metallurgy. It has excellent properties such as high hardness, good wear resistance, and good corrosion resistance. It is widely used in mechanical processing, geological exploration, mining and other fields. However, due to the high price and poor toughness of cemented carbide, it is difficult to produce products with large size and complex shape. Therefore, cemented carbide is connected with steel welding with good toughness, high strength, excellent processing performance and low cost. , which has important practical value.

The main technical difficulty in the connection between cemented carbide and steel is that there is a large difference in thermal expansion coefficient between cemented carbide and steel, so the joint will generate large thermal stress during the connection process, which will easily cause hard Cracks occur in the matrix of the alloy, which causes connection failure; secondly, how to prevent the high melting point carbide particles in the cemented carbide from agglomerating at the weld and the decarburization brittle phase (W, Fe rich due to the diffusion of C to the joint) , Co, etc. M ₆ C or M ₁₂ C composite carbides, often represented by η phase), is also a problem that needs to be solved to obtain high-quality joints.

At present, the connection methods of cemented carbide and steel mainly include brazing, diffusion welding, electron beam welding and partial instantaneous liquid phase connection. Brazing is a common method for connecting cemented carbide to steel, but brazed joints are not strong and have poor temperature resistance. Patent CN103071878A uses flake manganese brass as brazing material to realize the brazing connection of cemented carbide and low-alloy high-strength steel in an air furnace. This method does not require gas protection during the welding process, which reduces production costs, but the brazing material And the matrix is easily oxidized during the welding process, which affects the welding quality. Patent CN102909489 uses a Cu-Ag-Zn-Ni-Mn quenching solder to carry out vacuum brazing connection to hard alloy/steel, although it can improve the strength of the welded joint, but the solder preparation process is cumbersome; patent CN102962454 uses Ni-based Fe- Nb-Y-C is used as the filler to obtain cemented carbide and steel joints by electron beam welding, but the cost of electron beam welding is high and it is not suitable for large-scale production; At the same time, the connection of cemented carbide/steel joints can be realized. Although this method can obtain high-strength joints, the connection temperature is high (1450 ° C ~ 1600 ° C), and the shape of the parts is limited.

Contents of the invention

The technical problem to be solved by the present invention is to provide a rapid diffusion welding method for cemented carbide and steel in view of the deficiencies in the above-mentioned prior art. The method first uses pulse heating current to perform pulse activation treatment on the surface to be welded of the whole workpiece. The pulse heating current can instantly induce high-temperature plasma in the microscopic area of the surface to be welded, clean and activate the surface to be welded, and then use direct current heating The electric current conducts direct current sintering treatment on the surface to be welded of the whole workpiece, and accelerates the interdiffusion of interface elements, thereby obtaining a fast diffusion welded joint between cemented carbide and steel in a very short time, with fast welding speed, low temperature and small applied pressure And the advantages of high joint strength.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: a kind of fast diffusion welding method of cemented carbide and steel, it is characterized in that, this method comprises the following steps:

Step 1. Grind the surface to be welded of the cemented carbide and the surface to be welded of the steel until the surface is bright without scratches, and put the polished surface of the cemented carbide and the surface to be welded of the steel into acetone Ultrasonic cleaning in the solution to remove surface impurities, and dry with cold air;

Step 2. Polishing the metal flakes with sandpaper and then performing electrolytic polishing until the surface is bright and smooth; the thickness of the metal flakes is 50 μm to 800 μm;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 5MPa-40MPa, the pulse current to 200A-600A, and the pulse voltage to 10V- 30V, under the condition that the duty ratio is 50%, the whole workpiece is activated by pulse for 30s~60s; then the plasma activation sintering furnace is adjusted to the DC heating mode, the heating current is adjusted to 100A~600A, and the vacuum degree is 5Pa~15Pa. Under the condition of sintering temperature of 700℃～950℃, the whole workpiece after pulse activation treatment was sintered by direct current for 5min～14min, and the axial pressure was removed after cooling to room temperature with the furnace, so as to obtain the welded joint of cemented carbide and steel.

The above rapid diffusion welding method of cemented carbide and steel is characterized in that the cemented carbide in step 1 is YG8 cemented carbide, YG3 cemented carbide or YG6X cemented carbide.

The above-mentioned rapid diffusion welding method of cemented carbide and steel is characterized in that the steel in step 1 is 40Cr steel, No. 45 steel or 9SiCr steel.

The above-mentioned rapid diffusion welding method of cemented carbide and steel is characterized in that, in step 1, the specific process of grinding the surface to be welded of the cemented carbide is as follows: sequentially adopt 240#, 600#, 800# , 1000# and 1500# diamond sand table for step-by-step grinding.

The above-mentioned fast diffusion welding method of cemented carbide and steel is characterized in that, in step 1, the specific process of grinding the surface to be welded of the steel is: sequentially adopt 280#, 400#, 800# and 1200# # sandpaper for step-by-step sanding.

The above rapid diffusion welding method for cemented carbide and steel is characterized in that the metal sheet in step 2 is a nickel sheet or a copper sheet, and the thickness of the metal sheet is 100 μm to 600 μm.

The above-mentioned rapid diffusion welding method of cemented carbide and steel is characterized in that the thickness of the metal sheet is 150 μm.

The above-mentioned rapid diffusion welding method for cemented carbide and steel is characterized in that the axial pressure in step 4 is 5MPa-20MPa, the pulse current is 300A-500A, the pulse voltage is 15V-25V, and the time for pulse activation treatment is 35s-50s; the heating current is 200A-500A, the degree of vacuum is 8Pa-12Pa, the temperature of DC sintering treatment is 750°C-950°C, and the time is 6min-14min.

The above-mentioned fast diffusion welding method for cemented carbide and steel is characterized in that, the axial pressure is 14MPa, the pulse current is 400A, the pulse voltage is 20V, and the pulse activation treatment time is 40s; the heating current is 340A , the degree of vacuum is 10Pa, the temperature of DC sintering treatment is 850°C, and the time is 10min.

Compared with the prior art, the present invention has the following advantages:

1. The method of the present invention first utilizes a pulse heating current to carry out pulse activation treatment on the surface to be welded of the overall workpiece. The pulse heating current can instantly induce high-temperature plasma in the microscopic area of the surface to be welded, clean and activate the surface to be welded, and then Then use DC heating current to conduct DC sintering treatment on the surface to be welded of the whole workpiece to accelerate the interdiffusion of interface elements, so as to obtain a fast diffusion welded joint between cemented carbide and steel in a very short time, with fast welding speed and low temperature. , The applied pressure is small and the strength of the joint is high.

2. The present invention introduces a metal sheet with high toughness as an intermediate layer between the hard alloy to be welded and the steel, which can greatly alleviate the formation of the hard alloy and steel due to the excessive difference in thermal expansion coefficient. Larger residual stress improves the strength and reliability of the joint; on the other hand, the intermediate layer has a blocking effect, which can effectively prevent the carbon of the high melting point carbide in the cemented carbide from diffusing to the interface, thus avoiding the interface brittle phase and the cemented carbide The generation of decarburized brittle phase in the medium improves the connection performance of the joint.

3. The present invention has the advantages of reasonable process design, simple process and convenient batch production.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a SEM photo of the welding interface of the welded joint prepared in Example 1 of the present invention.

Fig. 2 is an enlarged SEM photo of the welding interface between cemented carbide and metal sheet in Fig. 1.

Fig. 3 is an enlarged SEM photo of the welded interface between the steel and the metal sheet in Fig. 1.

detailed description

The plasma activation sintering furnace used in each embodiment of the present invention is a plasma activation sintering furnace of model ED-PASⅢ produced by Elenix Company of Japan.

Example 1

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, dry with cold air; the hard alloy is YG8 hard alloy, the size of the hard alloy is Φ30mm×6mm, the steel is 40Cr steel, the size of the steel is Φ30mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a nickel flake, the thickness of the metal flake is 150 μm, and the metal flake is a disc with a diameter of 30 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: ₂₀ % of HF solution, 50% of _HNO3 solution and 30% of _H2SO4 solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 14MPa, the pulse current to 400A, and the pulse voltage to 20V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 40s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 340A, the vacuum degree to 10Pa, and the sintering temperature to 850°C Under the conditions of the pulse activation treatment, the whole workpiece was DC sintered for 10 minutes, and after cooling to room temperature with the furnace, the axial pressure was removed to obtain a welded joint between cemented carbide and steel.

Fig. 1 is the SEM photo of the welded joint welding interface prepared by the present embodiment, Fig. 2 is the enlarged SEM photo of the cemented carbide and the metal foil welding interface in Fig. 1, and Fig. 3 is the enlarged SEM of the steel and the metal sheet welding interface in Fig. 1 Photos, combined with Figure 1, Figure 2 and Figure 3, it can be seen that the welding interface between the metal sheet of the middle layer and the cemented carbide and the welding interface of the steel are connected straight, there is no obvious residual hole, and the overall workpiece is in good condition. The shear strength of the welded joint prepared in this example is 411MPa.

Example 2

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, and dry with cold air; the hard alloy is YG3 hard alloy, the size of the hard alloy is Φ10mm×6mm, the steel is No. 45 steel, and the size of the steel is Φ10mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a nickel flake, the thickness of the metal flake is 100 μm, and the metal flake is a disc with a diameter of 10 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: ₂₀ % of HF solution, 50% of _HNO3 solution and 30% of _H2SO4 solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 20MPa, pulse current to 300A, and pulse voltage to 15V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 50s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 200A, the vacuum degree to 12Pa, and the sintering temperature to 950°C Under the conditions of the pulse activation treatment, the whole workpiece was DC sintered for 6 minutes, and after cooling to room temperature with the furnace, the axial pressure was removed to obtain a welded joint between cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 379MPa.

Example 3

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, and dry with cold air; the hard alloy is YG6X hard alloy, the size of the hard alloy is Φ50mm×6mm, the steel is No. 45 steel, and the size of the steel is Φ50mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a copper flake, the thickness of the metal flake is 800 μm, and the metal flake is a disc with a diameter of 50 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: 20% of HF solution, 60% of _HNO3 solution and 20% of HCl solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in the plasma activation sintering furnace, adjust the plasma activation sintering furnace to pulse heating mode, adjust the axial pressure to 40MPa, pulse current to 200A, and pulse voltage to 10V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 30s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 100A, the vacuum degree to 15Pa, and the sintering temperature to 700°C Under the conditions of the pulse activation treatment, the whole workpiece was DC sintered for 14 minutes, and the axial pressure was removed after cooling to room temperature with the furnace to obtain a welded joint between cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 327MPa.

Example 4

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, dry with cold air; the hard alloy is YG3 hard alloy, the size of the hard alloy is Φ30mm×6mm, the steel is 9SiCr steel, the size of the steel is Φ30mm×10mm;

Step 2: Polish the metal flakes with sandpaper and then perform electrolytic polishing until the surface is bright and smooth; the metal flakes are copper flakes, the thickness of the metal flakes is 600 μm, and the metal flakes are discs with a diameter of 30 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: 20% of HF solution, 60% of _HNO3 solution and 20% of HCl solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 25MPa, pulse current to 300A, and pulse voltage to 30V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 60s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 600A, the vacuum degree to 5Pa, and the sintering temperature to 900°C Under the conditions of pulse activation, the whole workpiece after pulse activation treatment was sintered by direct current for 5 minutes, and the axial pressure was removed after cooling to room temperature with the furnace, so as to obtain the welded joint of cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 345MPa.

Example 5

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, dry with cold air; the hard alloy is YG8 hard alloy, the size of the hard alloy is Φ30mm×6mm, the steel is 9SiCr steel, the size of the steel is Φ30mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a copper flake, the thickness of the metal flake is 350 μm, and the metal flake is a disc with a diameter of 30 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: 20% of HF solution, 60% of _HNO3 solution and 20% of HCl solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 15MPa, pulse current to 400A, and pulse voltage to 20V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 40s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 350A, the vacuum degree to 10Pa, and the sintering temperature to 800°C Under the conditions of the pulse activation treatment, the whole workpiece was DC sintered for 10 minutes, and after cooling to room temperature with the furnace, the axial pressure was removed to obtain a welded joint between cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 367MPa.

Example 6

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, dry with cold air; the hard alloy is YG3 hard alloy, the size of the hard alloy is Φ30mm×6mm, the steel is 40Cr steel, the size of the steel is Φ30mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a nickel flake, the thickness of the metal flake is 300 μm, and the metal flake is a disc with a diameter of 30 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: ₂₀ % of HF solution, 50% of _HNO3 solution and 30% of _H2SO4 solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 5MPa, pulse current to 500A, and pulse voltage to 25V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 35s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 500A, the vacuum degree to 8Pa, and the sintering temperature to 750°C Under the conditions of the pulse activation treatment, the whole workpiece was DC sintered for 14 minutes, and the axial pressure was removed after cooling to room temperature with the furnace to obtain a welded joint between cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 338MPa.

Example 7

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, and dry with cold air; the hard alloy is YG8 hard alloy, the size of the hard alloy is Φ10mm×6mm, the steel is No. 45 steel, and the size of the steel is Φ10mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a nickel flake, the thickness of the metal flake is 50 μm, and the metal flake is a disc with a diameter of 10 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: ₂₀ % of HF solution, 50% of _HNO3 solution and 30% of _H2SO4 solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in a plasma-activated sintering furnace, adjust the plasma-activated sintering furnace to pulse heating mode, adjust the axial pressure to 5MPa, pulse current to 600A, and pulse voltage to 15V. Under the condition of 50%, pulse activation treatment of the whole workpiece for 50s; then adjust the plasma activation sintering furnace to direct current heating mode, keep the axial pressure constant, adjust the heating current to 500A, the vacuum degree to 12Pa, and the sintering temperature to 950°C Under the conditions of pulse activation, the whole workpiece after pulse activation treatment was sintered by direct current for 5 minutes, and the axial pressure was removed after cooling to room temperature with the furnace, so as to obtain the welded joint of cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 309MPa.

Example 8

Step 1. Use 240#, 600#, 800#, 1000# and 1500# diamond sand tables to grind the cemented carbide surface to be welded step by step until the surface is bright without scratches. 280#, 400#, 800# and 1200# sandpapers are polished step by step until the surface is bright without scratches, and the polished surface of the cemented carbide and the steel surface to be welded are put into the acetone solution for ultrasonic Clean and remove surface impurities, and dry with cold air; the hard alloy is YG6X hard alloy, the size of the hard alloy is Φ50mm×6mm, the steel is No. 45 steel, and the size of the steel is Φ50mm×10mm;

Step 2, after polishing the metal flake with sandpaper, perform electrolytic polishing and cleaning until the surface is bright and smooth; the metal flake is a copper flake, the thickness of the metal flake is 450 μm, and the metal flake is a disc with a diameter of 50 mm. The electrolyte solution for electropolishing cleaning is composed of the following raw materials in weight percentage: 20% of HF solution, 60% of _HNO3 solution and 20% of HCl solution;

Step 3, place the surface to be welded of the cemented carbide after ultrasonic cleaning in step 1 and the surface to be welded of the steel to be superimposed and docked, and place the metal sheet after electrolytic polishing and cleaning in step 2 on the surface to be welded of the cemented carbide and the surface to be welded of the steel The steel surfaces to be welded are closely fitted to obtain a whole workpiece;

Step 4. Place the overall workpiece described in step 3 in the plasma activation sintering furnace, adjust the plasma activation sintering furnace to pulse heating mode, adjust the axial pressure to 22MPa, the pulse current to 400A, and the pulse voltage to 20V. Under the condition of 50%, the whole workpiece was pulse activated for 45s; then the plasma activation sintering furnace was adjusted to the direct current heating mode, the axial pressure was unchanged, the heating current was adjusted to 350A, the vacuum degree was 10Pa, and the sintering temperature was 830°C Under the conditions of the pulse activation treatment, the whole workpiece was sintered by direct current for 9 minutes, and after cooling to room temperature with the furnace, the axial pressure was removed to obtain a welded joint between cemented carbide and steel.

The welding interface between the middle layer metal sheet and the cemented carbide and the steel welding interface of the welded joint prepared in this example is straight and straight, there is no obvious residual hole, and the overall workpiece is in good bonding condition. The shear strength of the welded joint prepared in this example is 349MPa.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still belong to the technical aspects of the present invention. within the scope of protection of the scheme.

Claims (8)

1. a hard alloy and the quick diffusion welding method of steel, it is characterised in that the method includes Following steps:

Step one, the junction to be welded of hard alloy and the junction to be welded of steel are all carried out grinding process to table Face light no marking, all puts the junction to be welded of the hard alloy after grinding process and the junction to be welded of steel Entering ultrasonic cleaning in acetone soln and remove surface impurity, cold wind dries up；

Step 2, clean to surface-brightening put down carrying out electrobrightening after sheet metal sand papering Sliding；Described sheet metal is nickel thin slice or copper foil, and the thickness of described sheet metal is 100 μm～600 μm；

Step 3, to be welded by the junction to be welded of the hard alloy after ultrasonic cleaning in step one and steel Face overlapping docking is placed, and the sheet metal after being cleaned by electrobrightening in step 2 is placed in hard alloy Fit tightly between junction to be welded and the junction to be welded of steel, obtain one-piece machine member；

Step 4, one-piece machine member described in step 3 is placed in plasma activated sintering stove, regulation Plasma activated sintering stove is PULSE HEATING pattern, and regulation axial compressive force is 5MPa～40MPa, pulse Electric current is 200A～600A, pulse voltage 10V～30V, by institute under conditions of dutycycle is 50% State one-piece machine member pulse activated and process 30s～60s；Then regulation plasma activated sintering stove is that direct current adds Heat pattern, it is 100A～600A that regulation adds thermocurrent, and vacuum is 5Pa～15Pa, in sintering temperature One-piece machine member direct current sintering processes after pulse activated being processed under conditions of being 700 DEG C～950 DEG C 5min～14min, cools to remove after room temperature axial compressive force with the furnace, obtains welding of hard alloy and steel Joint.

2. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Be characterised by, hard alloy described in step one be YG8 hard alloy, YG3 hard alloy or YG6X hard alloy.

3. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Being characterised by, steel described in step one is 40Cr steel, No. 45 steel or 9SiCr steel.

4. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Being characterised by, in step one, junction to be welded by described hard alloy carries out the detailed process of grinding process For: use the diamond sand table of 240#, 600#, 800#, 1000# and 1500# to carry out step by step successively Polishing.

5. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Being characterised by, the detailed process that the junction to be welded of described steel carries out in step one grinding process is: depend on The secondary sand paper using 280#, 400#, 800# and 1200# is polished step by step.

6. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Being characterised by, the thickness of described sheet metal is 150 μm.

7. according to the quick diffusion welding method of a kind of hard alloy described in claim 1 Yu steel, its Being characterised by, axial compressive force described in step 4 is 5MPa～20MPa, and pulse current is 300A～500A, pulse voltage 15V～25V, the time that pulse activated processes is 35s～50s；Described Adding thermocurrent is 200A～500A, and vacuum is 8Pa～12Pa, and the temperature of direct current sintering processes is 750 DEG C～950 DEG C, the time is 6min～14min.

8. according to the quick diffusion welding method of a kind of hard alloy described in claim 7 Yu steel, its Being characterised by, described axial compressive force is 14MPa, and pulse current is 400A, pulse voltage 20V, The time that pulse activated processes is 40s；The described thermocurrent that adds is 340A, and vacuum is 10Pa, directly The temperature 850 DEG C of stream sintering processes, the time is 10min.