Red copper and stainless steel welding part and argon tungsten-arc welding process

Abstract

The invention relates to the technical field of dissimilar material welding, and provides a red copper and stainless steel weldment and argon tungsten-arc welding process, which comprises the following steps of: selecting stainless steel and red copper with the thickness of more than or equal to 1mm and less than or equal to 3mm as a to-be-welded workpiece, oppositely butting the stainless steel and the red copper, controlling the width of a gap at the butting part of the stainless steel and the red copper, and forming a V-shaped groove at the butting part of the stainless steel and the red copper; the butt joint of the back faces of the red copper workpiece to be welded and the stainless steel workpiece to be welded is subjected to positioning spot welding; after tack welding, in an argon shielding gas atmosphere, a tungsten electrode is used as a welding heat source, a direct current positive connection mode is adopted for conducting backing welding on the butt joint position, only the tungsten electrode is used for heating in the welding process, the tungsten electrode is close to the side of the stainless steel workpiece to be welded, and welding wire filling is avoided; and after backing welding, the V-shaped groove is filled with a welding wire in the argon shielding gas atmosphere, and then a tungsten electrode is adopted as a welding heat source to conduct cosmetic welding on a backing welding seam. The method has the characteristics of high welding quality, simple and convenient welding process and relatively low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar material welding, and specifically to a tungsten welding part of copper and stainless steel and a tungsten inert gas arc welding process. Background Art

[0002] Copper and copper alloys have excellent physical, chemical and mechanical properties, and have good electrical and thermal conductivity. They are widely used in military, electric power, shipbuilding, automobiles, aerospace and other complex parts as well as heat conduction equipment and other fields. Due to the cross - application of copper and stainless steel, in order to give full play to the inherent properties of the materials, it is very necessary to connect copper and stainless steel into a dissimilar metal structure, which can greatly exert the role of the materials themselves. Due to the significant differences in the physical properties of copper and iron, the melting points and thermal conductivity coefficients of the two are significantly different, which all lead to great difficulties in welding the two. In addition, in the solid state of copper and steel, only limited solid solution occurs between the two. As the temperature rises, when the two are in the liquid state, they are infinitely soluble and no intermetallic compound is formed. In the past welding process of copper and stainless steel, welding methods such as gas welding, brazing and explosion welding are usually used. Since the oxy - acetylene flame generated by gas welding has a low temperature, it is difficult to overcome the defect of incomplete penetration caused by the fast heat dissipation of copper, and it is difficult to obtain good welding quality; the quality of the brazing weld may be affected by factors such as the choice of filler metal, brazing temperature and holding time, and defects such as discontinuous welds, pores and slag inclusions are likely to appear. However, when explosion welding is used to weld thin plates of copper and stainless steel, problems such as large welding deformation, hot cracks and penetration cracks are likely to occur. The above - mentioned welding problems seriously limit the further application of copper and iron in practical engineering.

[0003] In order to solve the problems such as the great difficulty in welding copper and stainless steel, the difficult control of welding quality and the complex welding process when implementing some welding methods. The present invention proposes a tungsten inert gas arc welding process for tungsten thin parts of copper and stainless steel with high welding quality, simple welding process and relatively low cost. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a tungsten welding part of copper and stainless steel and a tungsten inert gas arc welding process, which has the characteristics of high welding quality, simple welding process and relatively low cost.

[0005] To solve the above - mentioned technical problems, the first implementation solution given by the present invention is a tungsten inert gas arc welding process for a tungsten welding part of copper and stainless steel, including the following steps:

[0006] Select stainless steel workpieces to be welded and copper workpieces to be welded with a thickness of 1mm ≤ thickness ≤ 3mm, and horizontally butt - joint the stainless steel workpieces to be welded and the copper workpieces to be welded, control the gap width at the butt - joint of the two, and open a V - shaped groove at the butt - joint of the two;

[0007] Spot welding is carried out at the butt joint on the back of the copper workpiece to be welded and the stainless steel workpiece to be welded;

[0008] After spot welding, in an argon shielding gas atmosphere, using a tungsten electrode as the welding heat source, the back welding is carried out at the butt joint in the straight polarity DC mode. When welding, the tungsten electrode needs to be close to the side of the stainless steel workpiece to be welded;

[0009] After back welding, in an argon shielding gas atmosphere, use a welding wire to fill the V-groove, and then use a tungsten electrode as the welding heat source to cover the back weld.

[0010] Preferably, the opening angle of the V-groove is 30° - 45°, and the gap width is greater than 0 mm and less than or equal to 0.5 mm. If the gap width is greater than this range, lack of fusion defects will occur at the weld, affecting the forming quality.

[0011] Preferably, after multiple welding process tests, if the welding current is too small, incomplete penetration is likely to occur; if the welding current is too large, the workpiece to be welded is likely to be burned through. Therefore, when welding in the straight polarity DC mode, the welding current is 110 A - 130 A, the welding voltage is 13.5 V - 15 V, and the welding speed is 1.9 mm / s - 2.0 mm / s. ， The welding speed needs to match the current. Defects are likely to occur when the speed is too high (too low).

[0012] Preferably, when carrying out back welding, both the front and back of the butt joint of the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. Among them, the gas flow rate of the argon shielding gas on the front is 6 L / min - 10 L / min, and the gas flow rate of the argon shielding gas on the back is 10 L / min - 15 L / min.

[0013] The gas flow rate mainly protects the arc and the molten metal of the weld, making the performance of the weld joint better. If the gas flow rate on the front is too large, the molten pool metal will flow too fast and form defects. The gas flow rate on the back should be greater than that on the front. The air flow on the back is fast, resulting in impure shielding gas of argon and poor protection effect on the weld, affecting the forming quality.

[0014] Preferably, a welding wire with a diameter of 1.2 mm and a grade of HS201 is selected to fill the V-groove for cover welding. The welding current for cover welding is 110 A - 120 A, the welding voltage for cover welding is 13.5 V - 16 V, and the welding speed for cover welding is 1.6 mm / s - 1.8 mm / s.

[0015] Preferably, during the cover pass welding, both the front and back of the butt joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. The gas flow rate of the argon shielding gas on the front is 6 L / min to 10 L / min, and the gas flow rate of the argon shielding gas on the back is 10 L / min to 15 L / min.

[0016] The gas flow rate mainly protects the arc and the molten metal of the weld. The protection effect is good, and the performance of the weld joint is better. If the gas flow rate on the front is too large, it will cause the molten pool metal to flow too fast and form defects. The gas flow rate on the back should be greater than that on the front. The air flow on the back is fast, resulting in impure argon shielding gas and poor protection effect on the weld, affecting the forming quality.

[0017] Preferably, the argon shielding gas is supplied 1 s in advance before the root pass welding and the cover pass welding, and the supply of the argon shielding gas is stopped 2 s after the root pass welding and the cover pass welding.

[0018] The ventilation before and after welding is mainly to create an argon atmosphere, and the protection effect is better.

[0019] Preferably, before the positioning spot welding, the copper workpiece to be welded and the stainless steel workpiece to be welded within a range of 10 mm to 20 mm outward from the butt joint are cleaned with acetone before welding. If there are oxides on the weld surface that are not cleaned, defects such as pores and inclusions will be formed on the surface, affecting the forming quality.

[0020] The present invention also provides a thin copper and stainless steel workpiece prepared by the tungsten inert gas arc welding process for welding copper and stainless steel.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The tungsten inert gas arc welding process for thin copper and stainless steel parts given by the present invention has high welding quality for the welded thin copper and stainless steel parts, simple welding process and low welding cost. In this welding process, the thickness of the stainless steel workpiece to be welded and the copper workpiece to be welded and the gap width at the butt joint are first limited, which to a certain extent avoids the welding quality problems caused by incomplete penetration; in addition, the argon protective gas atmosphere avoids the problem of oxidation defects at the weld caused by the presence of air at the weld. At the same time, the positioning spot welding preliminarily fixes the gap at the butt joint, which is beneficial to improving the welding quality. The tungsten electrode is used as the welding heat source and is placed on the side close to the stainless steel workpiece in the gap, which not only provides the heat to melt the thin stainless steel part but also avoids the occurrence of the defect of incomplete penetration caused by the fast heat dissipation of the copper workpiece to be welded. After the weld is completed, the tungsten electrode is used to melt the welding wire in the V-shaped groove to complete the welding. This welding process does not require the selection of welding temperature, heat preservation duration, nor the selection of filler metal. This process is simpler. It has been proved that the welded thin copper and stainless steel parts obtained by this welding process do not have defects such as discontinuous welds, pores, slag inclusions, etc., nor problems such as large welding deformation, hot cracks and penetration cracks.

[0023] 2. The entire welding process of the welding process given by the present invention is simple to operate, has low production cost and is easy to implement; it can obtain a weld joint with good forming and quality of copper and stainless steel. Brief Description of the Drawings

[0024] Figure 1 is a schematic diagram of the weld gap and groove angle of the workpiece to be welded in the embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of the welding tool used in the welding process in the embodiment of the present invention.

[0026] Figure 3 is a macroscopic morphology diagram of the weld joint of the workpiece in the embodiment of the present invention.

[0027] Figure 4 is a macroscopic cross-sectional morphology diagram of the weld joint of the workpiece in the embodiment of the present invention.

[0028] Figure 5 is the stress-strain curve of the weld joint of the workpiece in the embodiment of the present invention.

[0029] Reference Signs

[0030] 1. Horizontal plate; 2. Pore; 3. Inlet pipe; 4. Welding torch; 5. Tungsten electrode; 6. Pressure plate; 7. Workpiece to be welded; 8. Clamping block; 9. Screw. Detailed Description of the Invention

[0031] In order to make the above-mentioned objects, features, and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0032] The inventors found that the physical properties of copper and iron are significantly different, and the melting points and thermal conductivity coefficients of the two are significantly different, which all lead to great difficulty in welding the two. In the past welding process of copper and stainless steel, welding methods such as gas welding, brazing, and explosion welding are usually used. Since the oxyacetylene flame generated by gas welding has a low temperature, it is difficult to overcome the defect of incomplete penetration caused by the fast heat dissipation of copper, and it is difficult to obtain good welding quality; the quality of the brazed weld may be affected by factors such as the selection of brazing filler metal, brazing temperature, and holding time, and defects such as discontinuous welds, pores, and slag inclusions are likely to occur.

[0033] In view of this, a tungsten inert gas arc welding process for thin copper and stainless steel parts given by the present invention has the characteristics of high welding quality, simple welding process, and relatively low cost.

[0034] As Figure 2 shown, the present invention provides a welding fixture used in the tungsten inert gas arc welding process for a copper and stainless steel welded part, including:

[0035] A horizontal plate 1 with a groove opened along the central axis on the top surface; a copper workpiece to be welded 7 and a stainless steel workpiece to be welded 7 can be placed on the top surface of the horizontal plate 1 on both sides of the groove. A plurality of air holes 2 are opened along the central axis direction of the horizontal plate 1 at the bottom of the groove. A cavity is provided in the horizontal plate 1 below the plurality of air holes 2. The cavity is communicated with the plurality of air holes 2. An air inlet pipe 3 communicated with the cavity is provided on the horizontal plate 1. The air inlet pipe 3 can be connected to an argon gas delivery unit to provide argon gas protection for the back during welding;

[0036] A clamping unit, including two pressing plates 6, an even number of clamping blocks 8, and a plurality of fastening bolts 9 for fixing the clamping blocks 8. The two pressing plates 6 are symmetrically arranged on the top of the copper workpiece to be welded 7 and the stainless steel workpiece to be welded 7. The even number of clamping blocks 8 are symmetrically arranged on the two pressing plates 6, and a plurality of bolt holes adapted to the end positions of the clamping blocks 8 are opened on the top surface of the horizontal plate 1 on both sides of the groove. One end of the clamping block 8 can press against the top surface of the pressing plate 6 on both sides of the groove. A through hole is opened at the other end of one end of the clamping block 8, and each fastening bolt 9 can pass through the through hole and be threadedly connected to the bolt hole.

[0037] The welding torch has its top connected to the power supply and its bottom connected with a tungsten electrode. The welding torch is also connected to an argon gas delivery unit through a gas pipeline, which is used to provide positive argon gas protection during welding.

[0038] It should be noted that when the present invention involves numerical ranges, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the step methods adopted are the same as those in Embodiment 1 to Embodiment 3, in order to avoid repetition, the present invention describes preferred embodiments. However, the present invention is not limited thereto, but can also be specifically implemented in other ways within the scope of the technical solutions defined in the appended claims.

[0039] Next, the technical solutions of the present invention will be further illustrated by specific examples.

[0040] Embodiment 1

[0041] A tungsten inert gas (TIG) welding process for a welded joint of copper and stainless steel includes the following steps:

[0042] Select stainless steel workpieces to be welded and copper workpieces to be welded with a thickness of 2 mm, and place the stainless steel workpieces to be welded and the copper workpieces to be welded horizontally and butted. Control the gap width at the butted part to be 0.1 mm, and open a V-shaped groove with an angle of 45° at the butted part of the copper workpieces to be welded and the stainless steel workpieces to be welded, as Figure 1 shown.

[0043] Before positioning spot welding, clean the copper workpieces to be welded and the stainless steel workpieces within 10 mm outward from the butted part with acetone for pre-welding cleaning.

[0044] Perform positioning spot welding on the butted part on the back of the copper workpieces to be welded and the stainless steel workpieces with the V-shaped groove opened.

[0045] Then, in an argon gas protection atmosphere with a purity of 99.99%, use the tungsten electrode as the welding heat source, and adopt the DC straight polarity connection method to perform root welding on the butted part of the copper workpieces to be welded and the stainless steel workpieces with the V-shaped groove opened, without wire filling during the welding process. Among them, the tungsten electrode is close to the side of the stainless steel workpiece. The welding current is 110 A, the welding voltage is 13.5 V - 15 V, the welding speed is 2.0 mm / s. The front and back of the butted part of the copper workpieces to be welded and the stainless steel workpieces are both protected by argon gas. Among them, the gas flow rate of the argon gas protection on the front is 6 L / min, and the gas flow rate of the argon gas protection on the back is 10 L / min. The argon gas protection gas is delivered 1 s in advance before welding and 2 s after welding.

[0046] Then, in an argon protective gas atmosphere, a welding wire with a diameter of 1.2 mm and a grade of HS201 is used to fill the V-groove, and a tungsten electrode is used as the welding heat source to cover the backing weld. The welding current for the cover pass welding is 110 A, the welding voltage for the cover pass welding is 13.5 V to 16 V, the welding speed for the cover pass welding is 1.8 mm / s. During the cover pass welding, both the front and back of the butt joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. Among them, the gas flow rate of the argon protective gas on the front is 6 L / min, and the gas flow rate of the argon protective gas on the back is 10 L / min. The argon protective gas is supplied 1 s in advance before welding and stopped 2 s after welding.

[0047] Example 2

[0048] A tungsten inert gas arc welding process for a welded joint of copper and stainless steel includes the following steps:

[0049] Select stainless steel workpieces to be welded and copper workpieces to be welded with a thickness of 3 mm, and place the stainless steel workpieces to be welded and the copper workpieces to be welded horizontally in butt joint, control the gap width at the butt joint between the two to be 0.1 mm, and open a V-groove with an angle of 45° at the butt joint between the copper workpiece to be welded and the stainless steel workpiece to be welded, as Figure 1 shown.

[0050] Before the positioning spot welding, clean the copper workpiece to be welded and the stainless steel workpiece to be welded within 15 mm outward from the butt joint with acetone for pre-welding cleaning

[0051] Perform positioning spot welding on the butt joint on the back of the copper workpiece to be welded and the stainless steel workpiece to be welded with the V-groove opened;

[0052] Then, in an argon protective gas atmosphere with a purity of 99.99%, use a tungsten electrode as the welding heat source and adopt the direct current straight polarity connection method to perform backing welding on the butt joint between the copper workpiece to be welded and the stainless steel workpiece with the V-groove opened, and no welding wire is filled during the welding process; among them, the tungsten electrode is close to the stainless steel workpiece side, the welding current is 120 A, the welding voltage is 13.5 V to 15 V, the welding speed is 2.0 mm / s, both the front and back of the butt joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. Among them, the gas flow rate of the argon protective gas on the front is 6 L / min, and the gas flow rate of the argon protective gas on the back is 10 L / min. The argon protective gas is supplied 1 s in advance before welding and supplied 2 s after welding;

[0053] Then, in an argon protective gas atmosphere, a welding wire with a diameter of 1.2 mm and a grade of HS201 is used to fill the V-groove, and a tungsten electrode is used as the welding heat source to cover the root weld. The welding current for the cover pass welding is 110 A, the welding voltage for the cover pass welding is 13.5 V to 16 V, the welding speed for the cover pass welding is 1.8 mm / s. During the cover pass welding, both the front and back of the butt joint of the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. Among them, the gas flow rate of the argon protective gas on the front is 6 L / min, and the gas flow rate of the argon protective gas on the back is 10 L / min. The argon protective gas is supplied 1 s in advance before welding and stopped 2 s after welding.

[0054] Example 3

[0055] A tungsten inert gas arc welding process for a welded joint of copper and stainless steel includes the following steps:

[0056] Select stainless steel workpieces to be welded and copper workpieces to be welded with a thickness of 1 mm, and place the stainless steel workpieces to be welded and the copper workpieces to be welded horizontally in butt joint, control the gap width at the butt joint between the two to be 0.1 mm, and open a V-groove with an angle of 45° at the butt joint of the copper workpiece to be welded and the stainless steel workpiece to be welded, as Figure 1 shown.

[0057] Before the positioning spot welding, clean the copper workpiece to be welded and the stainless steel workpiece to be welded within 20 mm outward from the butt joint with acetone for pre-welding cleaning

[0058] Perform positioning spot welding on the gap at the back of the butt joint of the copper workpiece to be welded and the stainless steel workpiece to be welded with the V-groove opened;

[0059] Then, in an argon protective gas atmosphere with a purity of 99.99%, use a tungsten electrode as the welding heat source and adopt the DC straight polarity connection method to perform root welding on the butt joint of the copper workpiece to be welded and the stainless steel workpiece with the V-groove opened, and there is no wire filling during the welding process; among them, the tungsten electrode is close to the stainless steel workpiece side, the welding current is 130 A, the welding voltage is 13.5 V to 15 V, the welding speed is 2.0 mm / s, both the front and back of the butt joint of the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas, among which the gas flow rate of the argon protective gas on the front is 6 L / min, and the gas flow rate of the argon protective gas on the back is 10 L / min, the argon protective gas is supplied 1 s in advance before welding and supplied 2 s after welding;

[0060] Then, in an argon protective gas atmosphere, a welding wire with a diameter of 1.2 mm and a grade of HS201 is used to fill the V-groove. A tungsten electrode is used as the welding heat source to perform capping welding on the root pass weld. The welding current for capping welding is 110 A, the welding voltage for capping welding is 13.5 V to 16 V, and the welding speed for capping welding is 1.8 mm / s. During capping welding, both the front and back of the butt joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas. The gas flow rate of the argon protective gas on the front is 6 L / min, and the gas flow rate of the argon protective gas on the back is 10 L / min. The argon protective gas is supplied 1 s in advance before welding and stopped 2 s after welding.

[0061] In the above Examples 1 to 3, tungsten inert gas (TIG) welding thin parts of copper and stainless steel with precise heat input control and high welding quality can be obtained. Next, the macroscopic morphology, cross-sectional macroscopic morphology, and stress of the welded joints of the copper and stainless steel thin parts prepared in Example 1 are analyzed.

[0062] Among them Figure 3 is the macroscopic morphology of the welded joint. Through Figure 3 it is obtained that the surface formation of the weld is good, without obvious defects such as slag inclusions and undercut, thus verifying the high welding quality.

[0063] Figure 4 is the cross-sectional macroscopic morphology of the welded joint. Through Figure 4 it is obtained that there are no defects such as pores and incomplete penetration in the weld joint, thus verifying the high welding quality.

[0064] Figure 5 is the stress-strain curve graph. Through Figure 5 it is obtained that the mechanical properties of the weld joint are good, indicating that the copper and stainless steel are welded. Since the tensile strength range of copper is 200 - 240 MPa, and the tensile strength at the fracture of the joint reaches more than 85% of that of copper, it shows that the quality of the weld joint is good.

[0065] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A tungsten inert gas arc welding process for copper and stainless steel weldments, characterized in that: The steps include: Select stainless steel workpieces and copper workpieces with a thickness of 1 mm ≤ ≤ 3 mm, and place them horizontally butt-jointed with each other, control the gap width at the joint, and open a V-shaped groove at the joint; Spot weld the butt joint between the copper workpiece to be welded and the back of the stainless steel workpiece to be welded; After spot welding, in an argon protective gas atmosphere, use a tungsten electrode as a welding heat source and use a direct current positive connection method to perform base welding at the butt joint. During welding, the tungsten electrode is close to the side of the stainless steel workpiece to be welded. After the base welding, in the argon protective gas atmosphere, the V-shaped groove is filled with welding wire, and then the tungsten electrode is used as the welding heat source to perform the cap welding on the base weld.

2. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 1 is characterized in that: The opening angle of the V-shaped groove is 30° to 45°, and the gap width is greater than 0 mm and less than or equal to 0.5 mm.

3. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 1 is characterized in that: When DC positive connection is used for welding, the welding current is 110A~130A, the welding voltage is 13.5V~15V, and the welding speed is 1.9mm / s~2.0mm / s.

4. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 1 is characterized in that: During base welding, the front and back sides of the joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas, wherein the gas flow rate of the argon protective gas on the front side is 6L / min~10L / min, and the gas flow rate of the argon protective gas on the back side is 10L / min~15L / min.

5. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 4 is characterized in that: The welding current of the cap welding is 110A~120A, the welding voltage of the cap welding is 13.5V~16V, and the welding speed of the cap welding is 1.6mm / s~1.8mm / s.

6. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 5, characterized in that: During the cap welding, the front and back sides of the joint between the copper workpiece to be welded and the stainless steel workpiece to be welded are protected by argon gas, wherein the gas flow rate of the argon protective gas on the front side is 6L / min~10L / min, and the gas flow rate of the argon protective gas on the back side is 10L / min~15L / min.

7. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 6, characterized in that: Argon shielding gas is supplied 1 second before base welding and cover welding, and the supply of argon shielding gas is stopped 2 seconds after base welding and cover welding.

8. The argon tungsten arc welding process for copper and stainless steel weldments according to claim 1, characterized in that: Before spot welding, clean the copper and stainless steel workpieces within 10mm to 20mm outside the butt joint before welding.

9. A copper and stainless steel welded part prepared by the argon tungsten arc welding process for copper and stainless steel welded parts according to any one of claims 1 to 8.

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