Method for laser welding of cemented carbide and high carbon alloy steel

Abstract

The application discloses a laser welding method of hard alloy and high-carbon alloy steel, which comprises the following steps: cleaning the welding position of the base material; filling the intermediate solder between the welding surfaces of the base material; pressing the base material in the direction of the close welding surfaces; welding the base material by using the laser beam under the protection of argon; coating the anti-oxidation paint on the surface of the welding joint of the base material and drying; heating the welded material to 750-850 DEG C, keeping warm for 1-2 hours; heating to 150-250 DEG C after oil quenching treatment, tempering for 2-3 hours, and then taking out the furnace and air cooling to room temperature; the anti-oxidation paint is mixed by the powder and the binder according to the mass ratio of 1:0.3-1, the powder comprises the following components according to the mass ratio: graphite powder 20-40%, alumina powder 30-50% and silica powder 30-50%, and the binder is water glass. The welding method solves the decarburization problem during the welding of the high-carbon alloy steel and improves the welding quality of the high-carbon alloy steel and the hard alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to a welding method between dissimilar metal materials, in particular to a laser welding method of cemented carbide and high-carbon alloy steel. BACKGROUND

[0002] At present, the tools for cutting and cutting high-strength steel materials mostly adopt the composite structure of base steel and cemented carbide (or diamond) welding, in which the base steel is the main load bearer in the cutting and cutting process, so the base steel material must have sufficient strength, toughness and hardness to withstand huge load. At the same time, the base steel needs to have certain wear resistance, especially when cutting high-strength steel materials above 600 MPa, the requirement for base steel material is further improved.

[0003] The base steel tends to use high-carbon alloy steel with carbon content greater than 0.6%, but the welding performance of high-carbon alloy steel and cemented carbide is poor. In the prior art, the welding of high-carbon alloy steel and cemented carbide mostly adopts high-temperature brazing process, that is, after the high-carbon alloy steel and cemented carbide are prepared and positioned, local high temperature is formed by induction heating or other methods, and connection is formed by high-temperature diffusion between high-carbon alloy steel and cemented carbide. The element diffusion speed is limited under high temperature, so a certain time is needed, and under high temperature, high-carbon alloy steel has surface decarburization and internal organization coarsening, etc., resulting in low welding strength. Even if laser beam welding is used to shorten the high temperature state time of the welding position, surface decarburization is still prone to occur at the joint after subsequent heat treatment. SUMMARY

[0004] In view of the defects of the prior art, one task of the present application is to provide a laser welding method of cemented carbide and high-carbon alloy steel, which solves the problems of decarburization and organization coarsening during welding of high-carbon alloy steel, and improves the welding quality of cemented carbide and high-carbon alloy steel.

[0005] The technical scheme of the present application is as follows: a laser welding method of cemented carbide and high-carbon alloy steel, comprising the following steps:

[0006] Step 1, cleaning the welding site surface of the cemented carbide base material and the high-carbon alloy steel base material;

[0007] Step 2, filling intermediate solder between the welding surface of the cemented carbide base material and the high-carbon alloy steel base material;

[0008] Step 3, pressing the cemented carbide base material and the high-carbon alloy steel base material in the direction of approaching the welding surface;

[0009] Step 4, under the protection of argon, laser beam is used to weld the cemented carbide base material and the high-carbon alloy steel base material;

[0010] Step 5, coating the surface of the welded joint of the hard alloy base material and the high-carbon alloy steel base material with an anti-oxidation paint and drying;

[0011] Step 6, heating the material treated in Step 5 to 750-850℃, holding for 1-2h; oil quenching and then heating to 150-250℃, holding for 2-3h, and then air cooling to room temperature after leaving the furnace;

[0012] The anti-oxidation paint is mixed by a powder and a binder in a mass ratio of 1:0.3-1, the powder comprises the following components in a mass ratio: graphite powder 20-40%, alumina powder 30-50%, and silica powder 30-50%, and the binder is water glass.

[0013] Further, the coating thickness of the anti-oxidation paint is 0.1-0.3mm.

[0014] Further, the intermediate solder comprises the following components in a mass ratio: Fe powder 30-40%, Co powder 30-50%, Ni powder 0-20%, and Cu powder 0-20%.

[0015] Further, the gap for filling the intermediate solder between the welding surfaces of the hard alloy base material and the high-carbon alloy steel base material is 0.1-0.4mm.

[0016] Further, the pressure in Step 3 is 0.1-0.3MPa.

[0017] Further, in Step 4, the laser spot diameter is selected to be 0.5-0.8mm, the welding speed is 0.5-1mm / s, the argon pressure is 0.1-0.3MPa, and the front and back surfaces are welded, and the welding depth of each surface does not exceed 2 / 3 of the welding seam depth.

[0018] Further, the hard alloy is tungsten-cobalt hard alloy or tungsten-titanium-tantalum-cobalt hard alloy or tungsten-titanium-niobium-cobalt hard alloy.

[0019] Further, the high-carbon alloy steel is high-carbon alloy steel with a carbon content of more than 0.7%.

[0020] The technical solution provided by the present application has the following advantages:

[0021] The concentrated heat of the laser beam promotes the local fusion welding between the high-carbon alloy steel and the hard alloy, the heat-acting time of the laser beam is short, the heat-acting on the organization around the welding seam is small, the argon protection can reduce the surface decarburization of the base material, in the heat treatment process, the surface decarburization reaction of the high-carbon steel is further prevented by coating the anti-oxidation paint on the surface of the welding joint, the generation of quality defects such as pores is prevented, and the welding quality problems of the high-carbon alloy steel and the hard alloy are improved. After welding by the method, the welding strength can reach more than 70% of the high-carbon alloy steel, meanwhile, fine microstructure morphology can be formed, good strength and toughness and bending strength are obtained, and the prepared composite material is suitable for the preparation of high-strength and high-toughness cutting tool products. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a schematic diagram of laser welding structure of hard alloy and high-carbon alloy steel. DETAILED DESCRIPTION

[0023] The application will be further described below in conjunction with examples, and it should be understood that the examples are only used to illustrate the application and not to limit the scope of the application. After reading the description, those skilled in the art can make various modifications of the equivalent forms of the description, which all fall within the scope defined by the claims attached hereto.

[0024] The laser welding method of the hard alloy and the high-carbon alloy steel in the embodiment of the application specifically comprises the following steps:

[0025] Step 1, cleaning the welding site surface of the hard alloy base material and the high-carbon alloy steel base material;

[0026] The cleaning of the surface of the hard alloy base material is to rub the welding surface with a steel brush or a file to expose a clean surface, and then wash with acetone;

[0027] The cleaning treatment of the surface of the high-carbon alloy steel base material: (1) removing rust and oil on the surface, first carrying out weak acid immersion process to remove surface rust, and then carrying out weak alkali immersion process to neutralize the effect of acid and eliminate oil and the like on the surface; (2) roughening and cleaning the surface, rubbing the welding surface with a steel brush or a file to expose a clean surface, and then washing with acetone.

[0028] Step 2, filling intermediate solder between the welding surfaces of the hard alloy base material and the high-carbon alloy steel base material;

[0029] Please refer to Figure 1 Fig. 1, the intermediate solder is placed in the gap between the welding surfaces of the hard alloy base material and the high-carbon alloy steel base material by a funnel, the size of the gap is generally 0.1-0.4 mm, and 0.2 mm is selected in the embodiment. The intermediate solder is mixed by Fe powder, Co powder, Ni powder and Cu powder, and the mass percentage of each component is shown in the specific embodiment.

[0030] Step 3, tighten the cemented carbide substrate and high carbon alloy steel substrate and apply pressure;

[0031] Please continue to combine Figure 1 As shown in the figure, the cemented carbide substrate 1 and the high carbon alloy steel substrate 2 are placed in the welding device, which includes a welding laser 3, an inert gas protection mechanism 4, a clamping device 5, a substrate positioning device 6, etc. The cemented carbide substrate 1 and the high carbon alloy steel substrate 2 are placed on the substrate positioning device 6 to ensure that the welding surfaces of the cemented carbide substrate 1 and the high carbon alloy steel substrate 2 are accurately butt-jointed, and the operation in step 2 is also carried out on the substrate positioning device 6. The clamping device on both sides includes a support 51, a clamping block 52 and an operation wheel 53. The cemented carbide substrate 1 and the high carbon alloy steel substrate 2 are clamped by the clamping block 52, and the clamping block drives the cemented carbide substrate 1 and the high carbon alloy steel substrate 2 to move relative to each other by rotating the operation wheel 53. After the positions of the cemented carbide substrate 1 and the high carbon alloy steel substrate 2 are determined and the set distance is reached, the corresponding intermediate solder 7 is filled, and the operation wheel 53 is further rotated to apply lateral pressure to the cemented carbide substrate 1 and the high carbon alloy steel substrate 2 to compress the intermediate solder 7 and ensure the airtightness of the interface between the substrates.

[0032] Step 4, laser beam welding under argon protection;

[0033] The laser welding mode is adopted, and the welding power is selected to be about 2 / 3 of the welding depth. Argon protection is used during welding. The pressure of argon is 0.1-0.3 MPa, and 0.1 MPa is selected in this embodiment. In the specific operation, first open the argon protection system, then turn on the laser welding power supply, adjust to the predetermined power, the spot diameter is selected to be 0.5-0.8 mm, and the welding speed is 0.5-1 mm / s. After single-sided welding is completed, the laser welding power supply and the argon protection system switch are turned off. The workpiece is turned over and the process is repeated for the other side welding.

[0034] Step 5, coating the surface of the welded joint of the cemented carbide substrate and the high carbon alloy steel substrate with an anti-oxidation paint and drying;

[0035] After welding is completed, a layer of anti-oxidation paint is applied to the surface of the welded joint of the workpiece, with a thickness of 0.1-0.3 mm, and then surface drying is performed at a temperature of 150-200℃ for 1-1.5 h. If there is blistering or peeling after drying, the paint is reapplied and dried again. The anti-oxidation paint is mixed with a binder in a certain proportion, the powder is composed of graphite powder, aluminum oxide powder and silicon oxide powder, and the binder is water glass. The binder is added to make the paint evenly coated, and the mixing ratio of the powder and the binder is 1:0.3-1. The ratio of 1:1 is selected in subsequent embodiments, and the percentage of each component of the powder is shown in the specific embodiments.

[0036] Step 6, heat treating the workpiece;

[0037] The workpiece after drying the anti-oxidation coating is put into a heating furnace and heated to 750-850℃, and kept for 1-3 hours; after oil quenching, it is heated to 150-250℃, and tempered for 2-3 hours, and then taken out and air cooled to room temperature.

[0038] According to the above specific implementation process, the laser welding of cemented carbide and high-carbon alloy steel is carried out according to the materials and process parameters shown in the following table to obtain the following examples and comparative examples, and the tensile test is carried out on each example and comparative example to obtain the tensile strength.

[0039]

[0040]

[0041]

Claims

1. A laser welding method for cemented carbide and high-carbon alloy steel, characterized in that, Includes the following steps: Step 1: Clean the surface of the welding area between the cemented carbide substrate and the high-carbon alloy steel substrate; Step 2: Fill the welding surfaces of the cemented carbide substrate and the high-carbon alloy steel substrate with intermediate solder. The intermediate solder is composed of the following components in the indicated mass ratios: 30-40% Fe powder, 30-50% Co powder, 0-20% Ni powder, and 0-20% Cu powder. Step 3: Apply pressure to the cemented carbide substrate and the high-carbon alloy steel substrate in a direction that brings the welding surfaces closer together; Step 4: Under argon protection, the cemented carbide substrate and the high-carbon alloy steel substrate are welded together using a laser beam. Step 5: Apply an anti-oxidation coating to the surface of the weld joint between the cemented carbide substrate and the high-carbon alloy steel substrate and dry it. The coating thickness of the anti-oxidation coating is 0.1 to 0.3 mm. Step 6: Heat the material treated in Step 5 to 750-850℃ and hold for 1-2 hours; after oil quenching, heat to 150-250℃, temper and hold for 2-3 hours, then remove from the furnace and air cool to room temperature. The anti-oxidation coating is made by mixing powder and binder at a mass ratio of 1:0.3 to 1. The powder includes the following components in the mass ratio: 20-40% graphite powder, 30-50% alumina powder and 30-50% silica powder. The binder is water glass. The cemented carbide is tungsten-cobalt cemented carbide, tungsten-titanium-tantalum-cobalt cemented carbide, or tungsten-titanium-niobium-cobalt cemented carbide. The high-carbon alloy steel is high-carbon alloy steel with a carbon content of more than 0.7%.

2. The laser welding method for cemented carbide and high-carbon alloy steel according to claim 1, characterized in that, The gap between the welding surfaces of the cemented carbide substrate and the high-carbon alloy steel substrate for filling the intermediate solder is 0.1 to 0.4 mm.

3. The laser welding method for cemented carbide and high-carbon alloy steel according to claim 1, characterized in that, The pressure applied in step 3 is 0.1 to 0.3 MPa.

4. The laser welding method for cemented carbide and high-carbon alloy steel according to claim 1, characterized in that, In step 4, the laser spot diameter is selected as 0.5-0.8 mm, the welding speed is 0.5-1 mm / s, the argon pressure is 0.1-0.3 MPa, and welding is carried out on both sides, with the welding depth on each side not exceeding 2 / 3 of the weld depth.

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