CN106238904A - A kind of hard alloy and the activated diffusion method of attachment of steel - Google Patents

Abstract

An activated diffusion connection method for cemented carbide and steel, which relates to the technical field of metal connection. The surface of cemented carbide and steel to be welded is polished and cleaned, butt-jointed and assembled, and an active agent or a metal containing an active agent is laid between the jointed surfaces. The interlayer is assembled to obtain the connecting piece; the active agent is at least one _of B, Li and B2O3 _; the connecting piece is placed in a diffusion welding furnace and a pre-pressure is applied; the diffusion welding furnace is evacuated to a vacuum degree in the furnace. When the temperature is higher than 10 ^‑1 Pa, fill the diffusion welding furnace with reducing gas, and start heating when the pressure in the furnace reaches the standard atmospheric pressure. Pressure, heat preservation and pressure holding for 7 to 60 minutes; after the diffusion welding of the connecting parts is completed, remove the pressure and cool with the furnace. The invention realizes the activated diffusion connection of hard alloy and steel under low vacuum, has high production efficiency and low cost, and has excellent high-temperature performance of welded hard alloy parts.

Description

A kind of activated diffusion bonding method of cemented carbide and steel

technical field

The invention relates to the technical field of connection between hard alloy and steel, in particular to an activated diffusion connection method between hard alloy and steel.

Background technique

Cemented carbide is synthesized from refractory metal carbides (such as TiC, WC, TaC, NbC, etc.) and binder metals (such as Co, Fe, Mo, etc.) by powder metallurgy. It has high hardness, high wear resistance and Good high temperature performance, widely used in the manufacture of coal and oil exploration and mining tools, metal cutting tools and mining tools. Because cemented carbide is expensive and has poor plasticity and toughness, cemented carbide tools are often used in connection with small pieces of cemented carbide and steel substrates, which can reduce costs and improve performance.

In current industrial applications, the common joining techniques of cemented carbide and steel include mechanical joining, brazing and diffusion welding. Among them, the mechanically connected cemented carbide tools have poor stability during use; the brazed cemented carbide tools have poor high-temperature performance; although the diffusion-welded cemented carbide tools have good high-temperature performance, the service temperature is It still has high strength at 450°C, but diffusion welding needs to be welded under high vacuum conditions, resulting in higher manufacturing costs for cemented carbide tools.

Contents of the invention

The technical problem to be solved by the present invention is: in the existing cemented carbide and steel connection technology, there are problems such as poor post-welding high-temperature performance, high vacuum degree requirement for activated connection, low connection efficiency, and high cost.

In order to achieve the above object, the technical solution of the present invention is: a method for activated diffusion connection of cemented carbide and steel, comprising the following steps:

Step 1. Alkali washing, pickling, grinding and distilled water washing are carried out on the surface of cemented carbide and steel to be welded sequentially, and then dried for later use;

Step 2, the surfaces to be welded of the hard alloy and the steel are butted and assembled, an activating agent or a metal interlayer containing an activating agent is laid between the butting surfaces, and an integral connector is obtained by assembling; the activating agents are B, Li and _At least one of B2O3 _;

Step 3. Place the integral connector in the diffusion welding furnace, apply a pre-pressure of 0.5-1.0 MPa to the integral connector, and close the furnace door;

Step 4. Vacuum the diffusion welding furnace. When the vacuum degree in the diffusion welding furnace is not higher than ^10-1 Pa, fill the diffusion welding furnace with reducing gas, and start heating when the pressure in the furnace reaches the standard atmospheric pressure. The heating rate 10-15°C/min, when the temperature in the furnace reaches 800-1200°C, apply an axial pressure of 5-12MPa to the integral joint, keep the pressure for 7-60min;

Step 5. After the diffusion welding of the overall connector is completed, remove the pressure, cool down to 100°C with the furnace, and take it out.

The reducing gas is at least one of H ₂ , CO, NO ₂ , NO, NH ₃ and CH ₄ .

The metal interlayer containing the active agent is any one of the metal foil coated with the active agent on the surface, the metal powder uniformly mixed with the active agent, and the metal coating film coated with the active agent on the surface, and the metal coating is sprayed or electroplated. A metallic layer on a carbide or steel surface.

The metal used in the metal foil, metal powder or metal coating is Ni or Cu.

The active agent is in the form of powder or foil.

The beneficial effects of the present invention are as follows:

(1) The present invention overcomes the strict requirement of the vacuum degree for diffusion welding, and the vacuum degree in the diffusion welding furnace only needs to be no higher than 10 ^-1 Pa, and does not require expensive vacuum equipment investment, which saves costs;

(2) In the present invention, an active agent or a metal interlayer containing an active agent is laid between the butt joint surfaces of the cemented carbide and the steel. The metal oxide reaction on the surface to be welded can remove the oxide film on the surface of the cemented carbide to be welded and the steel to be welded, increase the diffusion rate of the cemented carbide and steel, shorten the diffusion connection time, improve the connection efficiency, and reduce the welding time. defect, improve product quality;

(3) The reducing gas filled in the diffusion furnace can not only react with the metal oxide on the hard alloy and steel surface to be welded, remove the metal oxide, but also prevent the cemented carbide surface and the steel surface to be welded High temperature oxidation, increase the diffusion rate of cemented carbide and steel, shorten the diffusion connection time, improve connection efficiency, reduce welding defects, and improve product quality;

(4) Diffusion connection between hard alloy and steel is achieved. After welding, hard alloy tools have good high-temperature performance and good connection effect.

Description of drawings

Fig. 1 is the overall structure schematic diagram when cemented carbide of the present invention and steel are connected by activation diffusion;

Fig. 2 is the metal foil structure schematic diagram of the surface coating active agent of the present invention;

Fig. 3 is the schematic diagram of the metal powder uniformly mixed with active agent of the present invention;

Fig. 4 is the structural representation of the metal coating film of surface coating active agent of the present invention;

Reference signs are as follows: 1—upper indenter; 2—hard alloy; 3—activator; 4—steel; 5—lower indenter; 6—metal foil; 7—metal powder; 8—metal coating.

detailed description

Example 1

The YG6X cemented carbide with a size of φ9×9mm is connected to No. 45 steel by active diffusion.

Firstly, the surface to be welded of YG6X cemented carbide and No. 45 steel is subjected to alkali washing, pickling, grinding and distilled water rinse in sequence to ensure that the smoothness of the surface to be welded is Ra≤3.2μm, and the cold air is dried for use; then, the cemented carbide and The steel surfaces to be welded are butt-jointed and assembled, and a layer of boron powder is brushed between the butt surfaces without a metal interlayer, and the overall connection is assembled; then, the overall connection is placed on the upper and lower pressure heads of the diffusion welding furnace In between, apply a pre-pressure of 0.5MPa, close the furnace door; open the diffusion welding furnace to evacuate, and when the vacuum reaches 10 ^-1 Pa, fill the diffusion welding furnace with hydrogen, and start heating when the pressure in the furnace reaches the standard atmospheric pressure. The heating rate is 10°C/min. When the temperature in the furnace reaches 800°C, apply an axial pressure of 5MPa to the integral joint, keep the temperature and hold the pressure for 60 minutes; after the diffusion welding of the integral joint is completed, remove the pressure and cool down to 100°C with the furnace , Take out the connecting piece, that is to realize the activated diffusion connection between YG6X cemented carbide and No. 45 steel.

The test results of the welded joints are: (1) The activated diffusion welded joint has no defects and has a high welding rate; (2) The shear strength of the joint at room temperature is 203.5 MPa; (3) At a high temperature of 450 °C, the shear strength of the joint is 178.7 MPa .

Example 2

The YG15C cemented carbide with the size of φ12.5×9mm is connected with the No. 45 steel with the size of φ12.5×28mm by active diffusion.

Firstly, the surface to be welded of YG15C cemented carbide and No. 45 steel is subjected to alkali washing, pickling, grinding and distilled water rinse in sequence to ensure that the smoothness of the surface to be welded is Ra≤3.2μm, and the cold air is dried for use; then, the cemented carbide and The steel surfaces to be welded are butt-assembled, and a 100 μm thick Ni foil is laid between the butt surfaces, and the surface of the Ni foil is sprayed with a mixed powder of B and Li. The mass ratio of B powder and Li powder is 9:1, and the overall joint is assembled. ; Subsequently, place the integral connector between the upper and lower pressure heads of the diffusion welding furnace, apply a pre-pressure of 1.0 MPa, and close the furnace door; the diffusion welding furnace is turned on and vacuumed until the vacuum degree reaches 5×10 ^-2 Pa , fill the diffusion welding furnace with mixed gas of _H2 and CO, start heating when the pressure in the furnace reaches the standard atmospheric pressure, the heating rate is 15°C/min, when the temperature in the furnace reaches 1050°C, apply 12MPa to the overall joint Axial pressure, heat preservation and pressure holding for 7 minutes; after the diffusion welding of the overall joint is completed, the pressure is released, cooled to 100°C with the furnace, and the joint is taken out to realize the activated diffusion connection of YG15C cemented carbide and No. 45 steel.

The test results of the welded joints are: (1) The activated diffusion welded joint has no defects and has a high welding rate; (2) The shear strength of the joint at room temperature is 870 MPa; (3) At a high temperature of 400 °C, the four-point bending strength of the joint is 650 MPa .

Example 3

Active diffusion bonding of YG11 cemented carbide with a size of φ14×10mm and Cr12MoV steel.

Firstly, the surfaces to be welded of YG11 cemented carbide and Cr12MoV steel were washed with alkali, pickled, polished and distilled water in order to ensure that the roughness Ra of the surfaces to be welded was 1.25 μm, and dried with cold air for later use; then, the cemented carbide and steel The faces to be welded are butt-jointed and assembled, and a 100 μm thick Cu foil is laid between the butt faces, and B ₂ O ₃ powder is placed on both sides of the Cu foil, and the overall joint is assembled; then, the overall joint is placed on the top of the diffusion welding furnace Between the indenter and the lower indenter, apply a pre-pressure of 1.0MPa, close the furnace door; open the diffusion welding furnace to vacuumize, and when the vacuum reaches 10 ^-1 Pa, fill the diffusion welding furnace with a mixture of CH ₄ and H ₂ Gas, when the pressure in the furnace reaches the standard atmospheric pressure, start heating, the heating rate is 12°C/min, when the temperature in the furnace reaches 950°C, apply an axial pressure of 8 MPa to the overall connection, keep the pressure for 15 minutes; the overall connection is diffusion welded After completion, remove the pressure, cool down to 100°C with the furnace, and take out the connecting piece to realize the activated diffusion connection between the YG11 cemented carbide and the Cr12MoV steel.

The test results of the welded joints are as follows: (1) The activated diffusion welded joint has no defects and the welding rate is high; (2) The shear strength of the joint at room temperature is 645.8 MPa; (3) At a high temperature of 450 °C, the shear strength of the joint is 522.0 MPa .

Example 4

The YG11 cemented carbide with the size of φ14×10mm is connected with No. 45 steel by active diffusion.

First, the surface to be welded of YG11 cemented carbide and No. 45 steel was washed with alkali, pickled, polished and distilled water in order to ensure that the roughness Ra of the surface to be welded was 1.25 μm, and dried with cold air for later use; then, the cemented carbide and The surface to be welded of the steel is butt-jointed and assembled, and a Ni film with a thickness of 0.05mm is electroplated on the surface to be welded of No. 45 steel, and the surface of the Ni film is brushed with boron powder to assemble the overall connector; Between the upper pressure head and the lower pressure head of the furnace, a pre-pressure of 1.0 MPa is applied, and the furnace door is closed; the diffusion welding furnace is opened to vacuumize, and when the vacuum degree reaches 10 ^-1 Pa, fill the diffusion welding furnace with NO ₂ and H ₂ mixed gas, when the pressure in the furnace reaches the standard atmospheric pressure, start heating, and the heating rate is 12°C/min. When the temperature in the furnace reaches 1200°C, apply an axial pressure of 10MPa to the integral connection, and keep the temperature and pressure for 25min; the integral connection After the diffusion welding of the parts is completed, the pressure is released, cooled to 100°C with the furnace, and the connecting parts are taken out to realize the activated diffusion connection between the YG11 cemented carbide and the No. 45 steel.

The test results of welded joints are as follows: (1) The activated diffusion welded joint has no defects and the welding rate is high; (2) The shear strength of the joint at room temperature is 685.2 MPa; (3) At a high temperature of 450 °C, the shear strength of the joint is 536.3 MPa .

Claims (4)

1. a hard alloy and the activated diffusion method of attachment of steel, it is characterised in that: comprise the steps:

Step one, the surface to be welded of hard alloy and steel is carried out successively alkali cleaning, pickling, polishing and distilled water flushing process, afterwards Dry up standby；

Step 2, hard alloy is docked assembling with the surface to be welded of steel, between interface, lay activating agent or containing living Property agent metal sandwich, assembling obtain integrated connection part；Described activating agent is B, Li and B₂O₃In at least one；

Step 3, integrated connection part is placed in diffusion brazier in, to integrated connection part apply 0.5～1.0MPa precompression, close Closed furnace door；

Step 4, to diffusion welding (DW) stove evacuation, when in diffusion brazier, vacuum is not higher than 10^-1During Pa, it is filled with in diffusion brazier Reducibility gas, begins to warm up when furnace pressure reaches normal atmosphere, and the rate of heat addition is 10～15 DEG C/min, when temperature in stove When degree reaches 800～1200 DEG C, integrated connection part is applied the axial compressive force of 5～12MPa, heat-insulation pressure keeping 7～60min；

After step 5, integrated connection part diffusion welding (DW) complete, shed pressure, cool to 100 DEG C with the furnace, take out.

A kind of hard alloy the most as claimed in claim 1 and the activated diffusion method of attachment of steel, it is characterised in that: step 4 In, described reducibility gas is H₂、CO、NO₂、NO、NH₃And CH₄In at least one.

A kind of hard alloy the most as claimed in claim 1 and the activated diffusion method of attachment of steel, it is characterised in that: step 2 In, the described metal sandwich containing activating agent is the metal forming of surface-coated activating agent, is uniformly mixed with the metal powder of activating agent End, surface-coated activating agent metal coating in any one, described metal coating for spraying or plating at hard alloy or steel The metal level on surface.

A kind of hard alloy the most as claimed in claim 3 and the activated diffusion method of attachment of steel, it is characterised in that: described metal The metal that paper tinsel, metal dust or metal coating are used is Ni or Cu.