阅读说明：本技术 一种减材制备中间层的钨镍铁合金与高强钢扩散焊接方法 (Diffusion welding method for tungsten-nickel-iron alloy and high-strength steel for preparing intermediate layer by reducing material ) 是由 杨健 陆超 王玥 张知航 黄继华 陈树海 叶政 于 2021-07-06 设计创作，主要内容包括：一种减材制备中间层的钨镍铁合金与高强钢扩散焊接方法,属于异种金属材料焊接技术领域。本发明采用电解侵蚀工艺将钨镍铁合金表面一定厚度内钨颗粒相原位去除,仅余NiFeW相,实现在钨镍铁合金母材表面原位减材制备多孔NiFeW中间层。而后,将其与高强钢母材装配进行真空扩散焊接,最终形成钨镍铁合金/(NiFeW固溶体+弥散分布W颗粒)复合连接层/高强钢结构的焊接接头。本发明的优点在于：(1)在钨镍铁合金表面通过电解侵蚀原位减材制备的多孔NiFeW中间层结构适应性强；(2)焊接接头完全避免了界面金属间化合物的出现；(3)NiFeW固溶体+弥散分布W颗粒的复合连接层线膨胀系数介于钨镍铁合金与高强钢之间,有效缓和焊接热应力。(A tungsten-nickel-iron alloy and high-strength steel diffusion welding method for preparing an intermediate layer by reducing materials belongs to the technical field of dissimilar metal material welding. According to the method, an electrolytic erosion process is adopted to remove the tungsten particle phase in a certain thickness on the surface of the W-Ni-Fe alloy in situ, and only the NiFeW phase is left, so that the porous NiFeW intermediate layer is prepared on the surface of the W-Ni-Fe alloy base metal by in-situ material reduction. And then assembling the tungsten-nickel-iron alloy and the high-strength steel base metal for vacuum diffusion welding to finally form the welding joint of the tungsten-nickel-iron alloy/(NiFeW solid solution + dispersed W particles) composite connecting layer/high-strength steel structure. The invention has the advantages that: (1) the porous NiFeW intermediate layer prepared on the surface of the tungsten-nickel-iron alloy through electrolytic erosion in-situ material reduction has strong structural adaptability; (2) the appearance of interface intermetallic compounds is completely avoided by the welding joint; (3) the linear expansion coefficient of the composite connecting layer of the NiFeW solid solution and the dispersed W particles is between that of the W-Ni-Fe alloy and the high-strength steel, and the welding thermal stress is effectively relieved.)

1. A diffusion welding method for preparing a tungsten-nickel-iron alloy and high-strength steel of an intermediate layer by reducing materials is characterized in that the high-strength steel and the tungsten-nickel-iron alloy are used as base materials to be welded, an electrolytic erosion process is adopted to remove tungsten particle phases within a certain thickness of the surface of the tungsten-nickel-iron alloy in situ, only NiFeW phases remain, the porous NiFeW intermediate layer is prepared by reducing the materials on the surface of the tungsten-nickel-iron alloy in situ, then the porous NiFeW intermediate layer is assembled with the high-strength steel base material to carry out vacuum diffusion welding, and finally a welding joint of the tungsten-nickel-iron alloy and the high-strength steel is formed, wherein the welding joint takes NiFeW solid solution and W particles in dispersed distribution as a composite connecting layer.

2. The diffusion welding method for the W-Ni-Fe alloy and the high-strength steel for preparing the intermediate layer by reducing the materials as claimed in claim 1, is characterized in that the specific technological process comprises the following steps:

step 1, ultrasonically cleaning a base material to be welded with surface treated by acetone, and putting the base material into a constant-temperature drying box for later use;

step 2, preparing electrolytic corrosion liquid: the erosion liquid comprises 22-32 g/L, Na g of NaOH₂CO₃8-12 g/L, NaCl 10-15 g/L and Na₂MoO₄ 2.5-4.0g/L；

Step 3, carrying out electrolytic erosion on the to-be-welded surface of the W-Ni-Fe alloy by adopting the erosion liquid prepared in the step 2, wherein the erosion voltage is 6-12V, the erosion time is 15-60 min, the temperature of the erosion liquid is 35-60 ℃, and a porous NiFeW intermediate layer is prepared;

step 4, placing the W-Ni-Fe alloy of the porous NiFeW intermediate layer prepared in the step 3 into an ultrasonic cleaner for vibration cleaning, removing residual electrolytic corrosion liquid, drying, and assembling the W-Ni-Fe alloy side porous NiFeW intermediate layer surface and the to-be-welded surface of the high-strength steel side to form a W-Ni-Fe alloy/porous NiFeW intermediate layer/high-strength steel sandwich structure;

step 5, placing the assembled preset welding piece into a hearth of vacuum diffusion welding equipment and vacuumizing until the vacuum degree reaches 1 multiplied by 10^-3And when Pa, starting heating, increasing the temperature to 800-950 ℃ at the heating rate of 15-30 ℃/min, loading to the pressure of 40-60 MPa at the pressurizing rate of 5-10 MPa/min, increasing the temperature to 950-1050 ℃ at the heating rate of 5-10 ℃/min, keeping the temperature for 10-30 min, cooling at the cooling rate of 5-10 ℃/min, and obtaining the W-Ni-Fe alloy and high-strength steel welding joint with the NiFeW solid solution and the dispersed W particles as the composite connecting layer.

3. The diffusion welding method for the W-Ni-Fe alloy and the high-strength steel for preparing the intermediate layer by reducing the material as claimed in claim 2, wherein the cleaning time in the step 1 is 15-20 min, and the constant temperature drying temperature is 40-50 ℃.

4. The diffusion welding method of the inconel and the high-strength steel for the material reduction preparation intermediate layer according to claim 2, wherein the surface treatment in the step 1 is to grind and polish the surfaces of the inconel and the high-strength steel, so as to reduce the surface roughness, increase the contact area of base materials during welding and promote the diffusion of atoms at the joint.

5. The diffusion welding method for the W-Ni-Fe alloy and the high-strength steel for preparing the intermediate layer by reducing the material according to claim 2, wherein the oscillation cleaning time in the step 4 is 20-30 min.

6. The diffusion welding method for the inconel and the high-strength steel for the material reduction preparation intermediate layer according to claim 1, wherein the tungsten particles in a certain thickness on the surface of the inconel are removed in situ to a thickness of 100 +/-25 μm.

Technical Field

The invention belongs to the technical field of dissimilar metal material welding, and particularly provides a welding method suitable for a W-Ni-Fe alloy/high-strength steel complex structure with high melting point difference, large thermal mismatch and large forming tendency of brittle intermetallic compounds.

Background

The W-Ni-Fe alloy has the advantages of high melting point, high strength, high density, radiation resistance and the like, and is widely applied to the fields of advanced weapon manufacturing, nuclear industry, aerospace and the like. However, the poor room temperature toughness of the wolfram-nickel-iron alloy greatly limits the further expansion of the application range of the wolfram-nickel-iron alloy. In view of the current situation, researchers have proposed diffusion welding of the inconel and the high-strength steel to integrate the advantages of the high ductility and toughness of the high-strength steel and the high strength and high density of the inconel to obtain structural components meeting the service performance. In order to ensure the service performance of the component, the problem that the expansion coefficient difference between the W-Ni-Fe alloy and the high-strength steel wire is large (a) is solved when the high-strength welding of the W-Ni-Fe alloy and the high-strength steel is realized_{Tungsten nickel iron alloy}＝5～6×10^-6/K，a_{High strength steel}＝12～15×10^-6and/K), the interface after welding has two key problems of large welding thermal stress and strong reaction tendency of Fe element in the high-strength steel and W element in the W-Ni-Fe alloy, and Fe-W series brittle intermetallic compounds are easily generated at the interface. Aiming at the current situation, the current diffusion welding of tungsten-nickel-iron alloy and high-strength steel at home and abroad is realized by adding an intermediate layerThe method (1). However, although the introduction of the conventional intermediate layer avoids the occurrence of Fe-W intermetallic compounds, the occurrence of other intermetallic compounds (such as Ni-W compounds and Cu-Ti compounds) caused by the addition of the intermediate layer still weakens the strength of the diffusion welding joint of the W-Ni-Fe alloy and the high-strength steel, and the aim of releasing the welding thermal stress of the joint is difficult to achieve well; in addition, the existing intermediate layers are mostly introduced in the form of foil or powder, the intermediate layers are easy to slip and scatter during welding, so that the welding strength of the joint is reduced, and particularly in some complex structures (such as cambered surface welding structures), the intermediate layers in the form of foil or powder are difficult to apply. Therefore, how to adopt a proper method to prepare the intermediate layer which can effectively relieve the welding thermal stress, completely avoid the formation of brittle intermetallic compounds and has stronger structural adaptability for the diffusion welding of the tungsten-nickel-iron alloy and the high-strength steel becomes a key problem for the welding of the tungsten-nickel alloy and the high-strength steel complex component.

Disclosure of Invention

(1) The invention aims to solve the problems of large welding thermal stress of a joint, easy formation of brittle intermetallic compounds on an interface, poor structural adaptability of an intermediate layer and the like in the conventional diffusion welding of the tungsten-nickel-iron alloy and the high-strength steel, and provides a diffusion welding method of the tungsten-nickel-iron alloy and the high-strength steel for preparing the intermediate layer by reducing materials.

A diffusion welding method for preparing a tungsten-nickel-iron alloy and high-strength steel of an intermediate layer by reducing materials is characterized in that the high-strength steel and the tungsten-nickel-iron alloy are used as base materials to be welded, an electrolytic erosion process is adopted to remove tungsten particle phases in a certain thickness on the surface of the tungsten-nickel-iron alloy in situ, and only NiFeW phases remain, so that the porous NiFeW intermediate layer is prepared on the surface of the tungsten-nickel-iron alloy in situ by reducing materials. And then assembling the high-strength steel base material with the alloy and the high-strength steel base material for vacuum diffusion welding to finally form the W-Ni-Fe alloy and high-strength steel welding joint with the NiFeW solid solution and the dispersed W particles as the composite connecting layer.

The specific process comprises the following steps:

step 1, ultrasonically cleaning the base material to be welded after surface treatment by using acetone, and placing the base material to be welded into a constant-temperature drying box for later use.

Step 2, preparing electrolytic corrosion liquid: the erosion liquid comprises 22-32 g/L, Na g of NaOH₂CO₃8-12 g/L, NaCl 10-15 g/L and Na₂MoO₄ 2.5-4.0g/L。

And 3, carrying out electrolytic erosion on the to-be-welded surface of the W-Ni-Fe alloy by adopting the erosion liquid prepared in the step 2, wherein the erosion voltage is 6-12V, the erosion time is 15-60 min, and the temperature of the erosion liquid is 35-60 ℃ to prepare the porous NiFeW intermediate layer.

And 4, placing the W-Ni-Fe alloy of the porous NiFeW intermediate layer prepared in the step 3 into an ultrasonic cleaner for vibration cleaning, removing residual electrolytic corrosion liquid, drying, and assembling the W-Ni-Fe alloy side porous NiFeW intermediate layer surface and the to-be-welded surface of the high-strength steel side to form a W-Ni-Fe alloy/porous NiFeW intermediate layer/high-strength steel sandwich structure.

Step 5, placing the assembled preset welding piece into a hearth of vacuum diffusion welding equipment and vacuumizing until the vacuum degree reaches 1 multiplied by 10^-3And when Pa, starting heating, increasing the temperature to 800-950 ℃ at the heating rate of 15-30 ℃/min, loading to the pressure of 40-60 MPa at the pressurizing rate of 5-10 MPa/min, increasing the temperature to 950-1050 ℃ at the heating rate of 5-10 ℃/min, keeping the temperature for 10-30 min, cooling at the cooling rate of 5-10 ℃/min, and obtaining the W-Ni-Fe alloy and high-strength steel welding joint with the NiFeW solid solution and the dispersed W particles as the composite connecting layer.

The in-situ removal thickness of the tungsten particle phase within a certain thickness on the surface of the tungsten-nickel-iron alloy is 100 +/-25 microns.

In the step 1, the cleaning time is 15-20 min, and the constant-temperature drying temperature is 40-50 ℃; the surface treatment is to polish and polish the surfaces of the W-Ni-Fe alloy and the high-strength steel, reduce the surface roughness, increase the contact area of base metal during welding and promote the diffusion of atoms at a joint.

And 4, the vibration cleaning time is 20-30 min.

The invention has the following advantages:

(1) the porous NiFeW intermediate layer is prepared on the surface of the ferrotungsten alloy in situ by adopting an electrolytic erosion mode, so that the structural adaptability of the intermediate layer can be obviously improved, the phenomena of slippage, scattering and the like easily occurring in the process of welding a complex structure (such as a cambered surface welding structure) by the intermediate layer in the forms of conventional foils, powder and the like can be effectively avoided, and the strength of a joint is ensured to the greatest extent.

(2) A porous NiFeW interlayer was used. At the interface of the high-strength steel/NiFeW intermediate layer, no intermetallic compound is generated due to the characteristic of infinite mutual solubility between iron and nickel; at the interface of the W-Ni-Fe alloy/NiFeW intermediate layer, because tungsten has higher solid solubility in NiFeW solid solution, the generation of intermetallic compounds is also avoided. Thus, the occurrence of brittle intermetallic compounds is completely avoided in the entire joint.

(3) The finally obtained connecting layer is a composite connecting layer of NiFeW solid solution and W particles in dispersion distribution, the linear expansion coefficient of the connecting layer is between that of high-strength steel and tungsten-nickel-iron alloy, and welding thermal stress can be effectively relieved.

Drawings

FIG. 1 is a scanning electron microscope image of the surface morphology of the W-Ni-Fe alloy after electrolytic erosion. After electrolytic erosion, removing tungsten particles on the surface of the tungsten-nickel-iron alloy, wherein the remaining hollow reticular tissues are a porous NiFeW intermediate layer required by welding;

FIG. 2 is a scanning electron microscope image of the high strength steel/W-Ni-Fe alloy diffusion welded joint structure. The upper part is made of tungsten-nickel-iron alloy, the middle part is a (NiFeW solid solution + dispersed W particles) composite connecting layer, and the lower part is made of high-strength steel.

Detailed Description

Example 1

The embodiment is a welding method of a tungsten-nickel-iron alloy and high-strength steel. The tungsten-nickel-iron alloy is 90WNiFe alloy, and is cut into phi 36 multiplied by 20mm³A cylinder of (a); the high-strength steel is 60CrMnMo steel and is cut into phi 36 multiplied by 20mm³A cylinder of (2).

The specific process of the embodiment includes the following steps:

step 1, grinding the surfaces of the 90WNiFe alloy and the 60CrMnMo high-strength steel by 150-mesh, 400-mesh, 600-mesh, 800-mesh and 1000-mesh sand paper in sequence, and then polishing by adopting W0.5 type diamond polishing paste to ensure that the surfaces to be welded are smooth and have no oxide film.

Step 2, putting the polished 90WNiFe alloy and 60CrMnMo high-strength steel into alcohol, and ultrasonically cleaning for 15 min; and (3) putting the cleaned 90WNiFe alloy and 60CrMnMo high-strength steel into a vacuum drying oven, setting the drying temperature at 50 ℃ and the drying time at 20min, and drying for later use.

Step 3, weighing appropriate amount of NaOH and Na₂CO₃NaCl and Na₂MoO₄Preparing an electrolytic etching solution at 20 ℃: the erosion liquid comprises 22g/L, Na of NaOH₂CO₃8g/L, NaCl 10g/L and Na₂MoO₄ 2.5g/L。

And 4, performing electrolytic corrosion on the surface of the treated 90WNiFe alloy by using the prepared electrolytic corrosion solution: erosion voltage is 6V, erosion time is 15min, and the temperature of the erosion liquid is 35 ℃. The microstructure of the corroded 90WNiFe alloy surface is observed by a scanning electron microscope, and is shown in figure 1.

And 5, placing the prepared 90WNiFe alloy of the porous NiFeW intermediate layer into an ultrasonic cleaning instrument, vibrating and cleaning for 30min, removing residual electrolytic corrosion liquid, drying, and assembling with 60CrMnMo high-strength steel.

Step 6, placing the assembled piece to be welded into a constant temperature area of FNC-235 type vacuum diffusion welding equipment, firstly using a mechanical pump to pump low vacuum to a brazing furnace, and when the vacuum degree reaches 5 multiplied by 10^-2Continuously pumping high vacuum with diffusion pump when Pa, and when the vacuum degree reaches 1 × 10^-3At Pa, heating was started. Raising the temperature to 800 ℃ at a heating rate of 15 ℃/min, loading to 40MPa at a pressurizing rate of 5MPa/min, raising the temperature to 950 ℃ at a heating rate of 5 ℃/min, and cooling at a cooling speed of 10 ℃/min after heat preservation for 10min during welding. When the temperature in the furnace is reduced to 200 ℃, the diffusion pump is turned off, and the mechanical pump is turned off after 60 minutes. And when the furnace temperature is reduced to the room temperature, opening the furnace door and taking out the welding sample.

Step 7, cutting the welding joint of the 90WNiFe alloy obtained in the step 6 and the 60CrMnMo high-strength steel along the cross section of the axis, polishing the interface by using sand paper, and preparing the alloy into goldObserving the microstructure of the joint by using a scanning electron microscope, wherein the joint connecting layer is a composite connecting layer of black NiFeW solid solution and white W particles in dispersion distribution as shown in figure 2, so that the appearance of brittle intermetallic compounds is completely avoided, and the linear expansion coefficient of the composite connecting layer is a as detected by using a linear expansion coefficient detector_{Composite tie layer}＝8.3×10^-6a/K in the 90WNiFe alloy (a)_{90WNiFe alloy}＝5.8×10^-6A 60CrMnMo high-strength steel (a)_{60CrMnMo high-strength steel}＝13.6×10^-6The linear expansion coefficient of the/K) can effectively relieve the welding thermal stress; and (3) processing the welding sample piece obtained in the step (6) into a tensile sample, testing the tensile strength on an electronic universal testing machine, wherein the loading rate is 0.5mm/min, recording the maximum load output when the workpiece is sheared, and converting the joint shear strength into 283MPa according to the maximum load.

Example 2

The embodiment is a welding method of a tungsten-nickel-iron alloy and high-strength steel. The tungsten-nickel-iron alloy is 93WNiFe alloy, and is cut into phi 36 multiplied by 20mm³A cylinder of (a); the high-strength steel is 40Cr and cut into phi 36X 20mm³A cylinder of (2).

The specific process of the embodiment includes the following steps:

step 1, sequentially polishing the surfaces of 93WNiFe alloy and 40Cr high-strength steel by 150-mesh, 400-mesh, 600-mesh, 800-mesh and 1000-mesh sand paper, and then polishing by adopting W0.5 type diamond polishing paste to ensure that the surfaces to be welded are smooth and have no oxide films.

And 2, putting the polished 93WNiFe alloy and the polished 40Cr high-strength steel into alcohol, and cleaning for 15min by using ultrasonic waves. And (3) putting the cleaned 93WNiFe alloy and 40Cr high-strength steel into a vacuum drying oven, setting the drying temperature at 50 ℃ and the drying time at 20min, and drying for later use.

Step 3, weighing appropriate amount of NaOH and Na₂CO₃NaCl and Na₂MoO₄Preparing an electrolytic etching solution at 20 ℃: the erosion liquid comprises NaOH 25g/L, Na₂CO₃9g/L, NaCl 11g/L and Na₂MoO₄ 3.0g/L。

And 4, performing electrolytic corrosion on the surface of the treated 93WNiFe alloy by using the prepared electrolytic corrosion solution: erosion voltage is 8V, erosion time is 30min, and the temperature of the erosion liquid is 45 ℃. And observing the microstructure of the corroded 93WNiFe alloy surface by adopting a scanning electron microscope.

And 5, placing the 93WNiFe alloy with the prepared porous NiFeW intermediate layer into an ultrasonic cleaning instrument, vibrating and cleaning for 30min, removing residual electrolytic corrosion liquid, drying, and assembling with 40Cr high-strength steel.

Step 6, placing the assembled piece to be welded into a constant temperature area of FNC-235 type vacuum diffusion welding equipment, firstly using a mechanical pump to pump low vacuum to a brazing furnace, and when the vacuum degree reaches 5 multiplied by 10^-2Continuously pumping high vacuum with diffusion pump when Pa, and when the vacuum degree reaches 1 × 10^-3At Pa, heating was started. Raising the temperature to 850 ℃ at the heating rate of 25 ℃/min, loading the pressure to 50MPa at the pressurizing rate of 6MPa/min, raising the temperature to the welding temperature of 1000 ℃ at the heating rate of 8 ℃/min, and cooling after preserving the heat for 30min during welding at the cooling speed of 10 ℃/min. When the temperature in the furnace is reduced to 200 ℃, the diffusion pump is turned off, and the mechanical pump is turned off after 60 minutes. And when the furnace temperature is reduced to the room temperature, opening the furnace door and taking out the welding sample.

And 7, cutting the 93WNiFe alloy/40 Cr high-strength steel welding joint obtained in the step 6 along the section of the axis, polishing the interface by using sand paper, preparing a metallographic sample, and observing the microstructure of the joint by using a scanning electron microscope. Analyzing and identifying phase components by adopting X-ray diffraction and energy spectrum; and (3) processing the welding sample piece obtained in the step (6) into a tensile sample, testing the tensile strength on an electronic universal testing machine, wherein the loading rate is 0.5mm/min, recording the maximum load output when the workpiece is sheared, and converting the joint shear strength into 326MPa according to the maximum load.

Example 3

The embodiment is a welding method of a tungsten-nickel-iron alloy and high-strength steel. The tungsten-nickel-iron alloy is 95WNiFe alloy, and is cut into phi 36 multiplied by 20mm³A cylinder of (a); the high-strength steel is 42CrMoV and cut into phi 36 multiplied by 20mm³A cylinder of (2).

The specific process of the embodiment includes the following steps:

step 1, polishing the surfaces of 95WNiFe alloy and 42CrMoV high-strength steel by 150-mesh, 400-mesh, 600-mesh, 800-mesh and 1000-mesh sand paper in sequence, and then polishing by adopting W0.5 type diamond polishing paste to ensure that the surfaces to be welded are smooth and have no oxide film.

Step 2, putting the polished 95WNiFe alloy and 42CrMoV high-strength steel into alcohol, and cleaning for 15min by ultrasonic waves; and (3) putting the cleaned 95WNiFe alloy and 42CrMoV high-strength steel into a vacuum drying oven, setting the drying temperature at 50 ℃ and the drying time at 20min, and drying for later use.

Step 3, weighing appropriate amount of NaOH and Na₂CO₃NaCl and Na₂MoO₄Preparing an electrolytic etching solution at 20 ℃: the erosion liquid comprises 28g/L, Na g of NaOH₂CO₃11g/L, NaCl 13g/L and Na₂MoO₄ 3.5g/L。

And 4, performing electrolytic corrosion on the treated 95WNiFe alloy surface by using the prepared electrolytic corrosion solution: the erosion voltage is 10V, the erosion time is 45min, and the temperature of the erosion liquid is 55 ℃. And observing the microstructure of the corroded 95WNiFe alloy surface by adopting a scanning electron microscope.

And 5, placing the prepared 95WNiFe alloy of the porous NiFeW intermediate layer into an ultrasonic cleaning instrument, vibrating and cleaning for 30min, removing residual electrolytic corrosion liquid, drying, and assembling with 42CrMoV high-strength steel.

Step 6, placing the assembled piece to be welded into a constant temperature area of FNC-235 type vacuum diffusion welding equipment, firstly using a mechanical pump to pump low vacuum to a brazing furnace, and when the vacuum degree reaches 5 multiplied by 10^-2Continuously pumping high vacuum with diffusion pump when Pa, and when the vacuum degree reaches 1 × 10^-3At Pa, heating was started. Raising the temperature to 950 ℃ at a heating rate of 25 ℃/min, loading the pressure to 60MPa at a pressurizing rate of 5MPa/min, raising the temperature to 1050 ℃ at a heating rate of 10 ℃/min, and cooling after keeping the temperature for 20min during welding at a cooling speed of 10 ℃/min. When the temperature in the furnace is reduced to 200 ℃, the diffusion pump is turned off, and the mechanical pump is turned off after 60 minutes. And when the furnace temperature is reduced to the room temperature, opening the furnace door and taking out the welding sample.

And 7, cutting the 95WNiFe alloy/42 CrMoV high-strength steel welding joint obtained in the step 6 along the section of the axis, polishing the interface by using sand paper, preparing a metallographic sample, and observing the microstructure of the joint by using a scanning electron microscope. Analyzing and identifying phase components by adopting X-ray diffraction and energy spectrum; and (3) processing the welding sample piece obtained in the step (6) into a tensile sample, testing the tensile strength on an electronic universal testing machine, wherein the loading rate is 0.5mm/min, recording the maximum load output when the workpiece is sheared, and converting the joint shear strength into 311MPa according to the maximum load.

Example 4

The embodiment is a welding method of a tungsten-nickel-iron alloy and high-strength steel. The tungsten-nickel-iron alloy is 97WNiFe alloy, and is cut into phi 36 multiplied by 20mm³A cylinder of (a); the high-strength steel is 35CrMnSi and cut into phi 36 multiplied by 20mm³A cylinder of (2).

The specific process of the embodiment includes the following steps:

step 1, after the surfaces of the 97WNiFe alloy and the 35CrMnSi high-strength steel are sequentially polished by 150-mesh, 400-mesh, 600-mesh, 800-mesh and 1000-mesh sand paper, polishing is carried out by adopting W0.5 type diamond polishing paste, and the smooth surface to be welded is ensured without an oxide film.

Step 2, putting the polished 97WNiFe alloy and 35CrMnSi high-strength steel into alcohol, and cleaning for 15min by ultrasonic waves; and (3) putting the cleaned 97WNiFe alloy and 35CrMnSi high-strength steel into a vacuum drying oven, setting the drying temperature at 50 ℃ and the drying time at 20min, and drying for later use.

Step 3, weighing appropriate amount of NaOH and Na₂CO₃NaCl and Na₂MoO₄Preparing an electrolytic etching solution at 20 ℃: the erosion liquid comprises NaOH 32g/L, Na₂CO₃12g/L, NaCl 15g/L and Na₂MoO₄ 4.0g/L。

And 4, performing electrolytic corrosion on the surface of the treated 97WNiFe alloy by using the prepared electrolytic corrosion solution: the erosion voltage is 12V, the erosion time is 60min, and the temperature of the erosion liquid is 60 ℃. And observing the microstructure of the corroded 97WNiFe alloy surface by adopting a scanning electron microscope.

And 5, placing the 97WNiFe alloy with the prepared porous NiFeW intermediate layer into an ultrasonic cleaning instrument, vibrating and cleaning for 30min, removing residual electrolytic corrosion liquid, drying, and assembling with 35CrMnSi high-strength steel.

Step 6, placing the assembled piece to be welded into a constant temperature area of FNC-235 type vacuum diffusion welding equipment, firstly using a mechanical pump to pump low vacuum to a brazing furnace, and when the vacuum degree reaches 5 multiplied by 10^-2Continuously pumping high vacuum with diffusion pump when Pa, and when the vacuum degree reaches 1 × 10^-3At Pa, heating was started. Raising the temperature to 950 ℃ at the temperature raising rate of 30 ℃/min, loading the pressure to 50MPa at the pressurizing rate of 10MPa/min, raising the temperature to the welding temperature of 1000 ℃ at the temperature raising rate of 5 ℃/min, and cooling after heat preservation for 20min during welding at the cooling speed of 5 ℃/min. When the temperature in the furnace is reduced to 200 ℃, the diffusion pump is turned off, and the mechanical pump is turned off after 60 minutes. And when the furnace temperature is reduced to the room temperature, opening the furnace door and taking out the welding sample.

And 7, cutting the welded joint of the 97WNiFe alloy obtained in the step 6 and the 35CrMnSi high-strength steel along the section of the axis, polishing the interface by using sand paper, preparing a metallographic sample, and observing the microstructure of the joint by using a scanning electron microscope. Analyzing and identifying phase components by adopting X-ray diffraction and energy spectrum; and (3) processing the welding sample piece obtained in the step (6) into a tensile sample, testing the tensile strength on an electronic universal testing machine, wherein the loading rate is 0.5mm/min, recording the maximum load output when the workpiece is sheared, and converting the joint shear strength into 298MPa according to the maximum load.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.