CN108544058A - A kind of High Efficiency Welding Process for titanium or titanium alloy thin plate - Google Patents

Abstract

The invention relates to a high-efficiency welding process for titanium and titanium alloy thin plates. Double tungsten argon arc welding is used to weld workpieces. Two welding torches are connected to a DC power supply. The welding torch located in front is the main welding torch along the welding direction. The welding torch located at the back is the auxiliary welding torch. During the welding process, the main electrode current _IL on the main welding torch is greater than the auxiliary electrode current I _T on the auxiliary welding torch, and the distance between the tip of the main electrode on the main welding torch and the workpiece is less than or equal to that on the auxiliary welding torch The distance between the tip of the auxiliary electrode and the workpiece, and the distance D between the main electrode and the auxiliary electrode is 11-15mm. Compared with the prior art, the invention can fully suppress welding defects such as undercut during high-speed welding, has good weld shape, can reach a welding speed of more than 3m/min, and has excellent joint quality and the like.

Description

A high-efficiency welding process for titanium and titanium alloy thin plates

technical field

The invention relates to the field of welding titanium and titanium alloy thin plates, in particular to an efficient welding process for titanium and titanium alloy thin plates.

Background technique

Titanium and titanium alloys have low thermal conductivity, high specific strength, and corrosion resistance. They are excellent structural materials and play a huge role in aerospace, petrochemical, and seawater desalination industries. For titanium and titanium alloy sheets with a thickness of 3mm or less, the most commonly used welding method is argon tungsten arc welding. The traditional argon tungsten arc welding has a beautiful weld seam, stable arc and easy automation at a small welding speed. However, under high-speed welding conditions, defects such as undercut, burn-through and incomplete penetration will appear in the weld.

Double tungsten argon arc welding can effectively increase the deposition rate and suppress defects under high-speed welding conditions. A single welding torch double tungsten argon arc welding method (T-TIG) was first proposed by Japanese welding workers. The method is to weld through the coupled arc generated by two mutually independent tungsten electrodes set in the same welding torch. This welding method improves the arc pressure distribution and can suppress welding defects, but this method has higher requirements on the welding power supply. Generally, two interleaved and delayed pulse currents are used to ensure that the double arc interference is small and the stability is good. Debugging brings certain difficulties, and it is not easy to popularize and apply. If two DC power supplies are used, one welding torch is responsible for preheating, and the other welding torch is responsible for covering the surface, which can also increase the deposition rate and suppress welding defects. However, due to the magnetic field formed around the arcs, they also interfere with each other; the interaction of the arcs can make the welding process unstable.

Therefore, solving the above problems and obtaining joints with reliable quality is of great significance for the welding of titanium and titanium alloy thin plates.

Contents of the invention

The purpose of the present invention is to provide a high-efficiency welding process for titanium and titanium alloy thin plates in order to overcome the above-mentioned defects in the prior art, which is a welding process method of double tungsten argon arc welding.

The purpose of the present invention can be achieved through the following technical solutions:

A high-efficiency welding process for titanium and titanium alloy thin plates. Double tungsten argon arc welding is used to weld the workpiece. Two welding torches are connected to a DC power supply. The welding torch located in the front is the main welding torch, and the welding torch located in the back is defined along the welding direction. If the welding torch is an auxiliary welding torch, then during the welding process, the main electrode current _IL on the main welding torch is greater than the auxiliary electrode current I _T on the auxiliary welding torch, and the distance between the tip of the main electrode on the main welding torch and the workpiece is less than or equal to the auxiliary electrode on the auxiliary welding torch The distance between the tip and the workpiece, and the distance D between the main electrode and the auxiliary electrode is 11-15 mm.

Preferably, the ratio I _L / _IT of the main electrode current _{I L} to the auxiliary electrode current I _T is 1.2˜1.5.

Preferably, when the welding speed is 2.5-3m/min and the workpiece thickness δ=0.8-1.5mm, the main electrode current I _L is 180-300A, and the auxiliary electrode current I _T is 120-200A. In addition, under a certain welding speed, the thicker the workpiece, the greater the welding current required, preferably satisfying (I _L + _IT )/δ=300-400A/mm.

Preferably, the distance between the tip of the main electrode and the auxiliary electrode and the workpiece is 2-4 mm. During the welding process, ensure that the tungsten tip of the main electrode is slightly lower than the tip of the auxiliary electrode.

Preferably, during the welding process, the inclination angle θ ₁ of the main welding torch is 75°-80°, and the inclination angle θ ₂ of the auxiliary welding torch is 75°-80°.

Preferably, for the non-groove butt welding of pure titanium TA2 workpieces, the welding gap is controlled at 0-30% of the workpiece thickness δ.

Preferably, during the welding process, the argon flow rate of the main welding torch is 15-20 L/min, and the argon flow rate of the auxiliary welding torch is 15-20 L/min.

Compared with the prior art, the double argon tungsten arc welding welding process of titanium and titanium alloy thin plates adopted by the present invention improves the welding efficiency by 200% compared with the traditional argon tungsten arc welding, which can solve the mutual interference effect of double arcs and inhibit the bite Welding defects such as edge, burn-through and incomplete penetration ensure the welding quality.

Description of drawings

Fig. 1 is the schematic diagram when the present invention welds;

Fig. 2 is the arc shape of different electrode spacings under high-speed photography according to the present invention;

Figure 3 is a comparison diagram of current and voltage waveforms with and without arc interference;

Fig. 4 is the distribution schematic diagram of the welding gun of different inclination angle;

Fig. 5 is butt welding seam appearance, joint structure and tensile mechanical properties of the present invention;

In the figure, 1-main welding torch, 2-auxiliary welding torch, 3-workpiece.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Fig. 1, the high-efficiency welding process of titanium and titanium alloy thin plates of the present invention is double argon tungsten arc welding, specifically is to weld workpiece 3 by a DC welding power supply and two argon tungsten arc welding torches, and simultaneously, along In the welding direction, one welding torch is placed in front, which is the main welding torch 1, and one welding torch is placed in the back, which is the auxiliary welding torch 2. The included angles between the main welding torch 1 and the auxiliary welding torch 2 and the workpiece 3 are θ ₁ and θ ₂ respectively. The electrode spacing of the welding torch is recorded as D. The main electrode current _IL of the main welding torch 1 is greater than the auxiliary electrode current I _T of the auxiliary welding torch 2, mainly for the purpose of preheating the molten pool formed by the main electrode, and the auxiliary electrode continues to heat the molten pool formed by the main electrode to obtain a larger The penetration depth, welding voltage depends on the distance between the tip of the tungsten electrode and the workpiece 3, the distance between the tip of the tungsten electrode of the main electrode and the workpiece 3 is less than or equal to the distance between the tip of the tungsten electrode of the auxiliary electrode and the workpiece 3.

Referring to Fig. 2, when adopting the double tungsten argon arc welding process method of the titanium and titanium alloy thin plate of the present invention to weld under different electrode spacings, such as when the electrode spacing D=7mm, the coupling arc swings upwards in a pointed shape, causing an arc Energy loss, the heated molten pool area is small, and the weld seam is not penetrated; when the electrode spacing D=11mm and 15mm, no coupled arc is generated, and it is in the eutectic pool state, and sufficient penetration can be obtained; the electrode spacing D=19mm , no coupling arc is generated, and it is in a non-eutectic pool state, but due to the long distance between the electrodes, the auxiliary electrode cannot fully heat the main electrode to form a molten pool, resulting in incomplete penetration. It can be seen that the electrode spacing D is in the range of 11-15mm. Excellent implementation.

See Figure 3(a), when the electrode spacing D=7mm, the coupled arc during welding is very unstable, and the current of the main electrode fluctuates greatly. This fluctuating current makes the arc unstable and easily causes welding Defects; see Figure 3(b), when the electrode spacing D = 15mm, the current and voltage waveforms do not change, and the welding process is stable. Here, L represents the main electrode, and T represents the auxiliary electrode.

Referring to Fig. 4(a), when welding is carried out under the conditions of the inclination angle θ ₁ =90° of the main torch 1 and the inclination angle θ ₂ =80° of the auxiliary torch 2, since the main torch 1 is perpendicular to the workpiece 3, the main arc The pressure is perpendicular to the lower molten pool, which cannot effectively heat the backward flowing intermediate molten pool, resulting in poor fluidity of liquid metal and welding defects; see Figure 4(b), when the inclination angle θ 1 of the main welding torch ₁ = 80° , welding is carried out under the condition of inclination angle θ ₂ =80° of the auxiliary welding torch 2, on the one hand, the middle molten pool where the liquid metal flows backward is suppressed, on the other hand, the two arcs simultaneously heat the middle molten pool, the temperature of the molten pool is relatively high, and the surface The tension is small, and the molten pool is easy to spread outward, thus forming a weld with uniform width and _no obvious undercut; see Fig. Welding is carried out under the condition of inclination angle θ ₂ =90°. Since the auxiliary welding torch 2 is vertical, the auxiliary arc cannot effectively restrain the main arc from forming an intermediate molten pool that flows backward, and the auxiliary arc does not effectively heat the molten pool, and the fluidity becomes Poor, resulting in welding defects.

In a preferred embodiment of the present invention, the welding parameters of the double tungsten argon arc welding process are as follows: the tungsten rod diameter is 3.2mm, the shielding gas is argon with a purity of 99.9%, and the argon flow of the main torch 1 is 15- 20L/min, the argon gas flow rate of auxiliary welding torch 2 is 15~20L/min; the main electrode current I _L is greater than the auxiliary electrode current I _T , I _L =180~300A, I _T =120~200A, and I _L /I _T is guaranteed to be 1.2 ～1.5 range; welding speed 2.5～3m/min, distance between electrode tip and workpiece 3 2～4mm, electrode spacing D=11mm～15mm, inclination angle θ 1 of main welding torch ₁ =75°～80°, auxiliary welding torch 2 The inclination angle θ ₂ =75°～80°.

Example 1

In the following, a pure titanium TA2 thin plate with a thickness of 1.24mm is taken as an example to describe in detail. The double tungsten argon arc welding process is adopted, the welding power source is Xinwei MPT-500D, the diameter of the tungsten rod is 3.2mm, the protective gas is argon with a purity of 99.9%, and the gas flow rate is 15-20L/min.

1. Preparation before welding

Adjust the torch angle and electrode spacing according to actual welding needs; in this example, the inclination angle of main welding torch 1 is θ ₁ =80°, the inclination angle of auxiliary welding torch 2 is θ ₂ =80°, and the electrode spacing D is within the range of 11-15mm.

2. Debug welding parameters

The main electrode current I _L is greater than the auxiliary electrode current I _T , I _L / _IT = 1.2 to 1.5, and the tip of the main electrode is slightly lower than the tip of the auxiliary electrode;

Set the parameters of the welding power supply, the main electrode current _IL = 230-240A, the auxiliary electrode current I _T = 170-180A; the welding speed is 3m/min; the distance between the tip of the tungsten electrode and the workpiece 3 is about 2-4mm, and then weld.

Finally, the appearance, microscopic appearance and mechanical properties of the butt weld obtained in this embodiment are analyzed, as shown in Figure 5 (a), the front weld and the back weld are good, and there are no obvious defects such as undercut and depression; Although a slight undercut can be seen in the microscopic appearance of Figure 5(b), the measured maximum undercut is only 0.0898mm, which is less than 0.1δ, and the undercut is qualified; as shown in Figure 5(c), (d) As shown, the tensile strength of the joint is 434Mpa, and the elongation is 31.4%. The tensile specimen breaks at the base material, with obvious necking, which is a ductile fracture.

To sum up, the double tungsten argon arc welding process method of the embodiment of the present invention has the following advantages:

(1) When welding titanium and titanium alloy thin plates, the welding speed is greatly improved. Compared with traditional argon tungsten arc welding, the welding efficiency is increased by more than 200%.

(2) The advantages of argon tungsten arc welding are retained, the welding process is stable, easy to realize automation, and it is suitable for efficient welding of thin-walled straight seam pipes.

(3) By adopting the preferred process parameters of the present invention, the quality of the welded joint is excellent, the tensile strength can reach 434Mpa, and the elongation is 31.4%.

Example 2

Compared with Example 1, most of them are the same, except that in this example, the welding process parameters are controlled as:

The argon gas flow rate of the main welding torch 1 is 15L/min, and the argon gas flow rate of the auxiliary welding torch 2 is 15L/min; the main electrode current I _L is greater than the auxiliary electrode current I _T , I _L =180A, I _T =120A; the welding speed is 2.5～3m/min , the distance between the tip of the electrode and the workpiece 3 is about 2 mm, the distance between the electrodes is D=11 mm, the inclination angle θ ₁ of the main welding torch 1 =75°, and the inclination angle θ 2 of the auxiliary welding torch ₂ =75°.

Example 3

Compared with Example 1, most of them are the same, except that in this example, the welding process parameters are controlled as:

The argon gas flow rate of the main welding torch 1 is 20L/min, and the argon gas flow rate of the auxiliary welding torch 2 is 20L/min; the current I _L of the main electrode is greater than the current I _T of the auxiliary electrode, I _L =300A, I _T =200A; the welding speed is 2.5～3m/min , the distance between the tip of the electrode and the workpiece 3 is 4 mm, the distance between the electrodes is D=15 mm, the inclination angle θ ₁ of the main welding torch 1 =80°, and the inclination angle θ 2 of the auxiliary welding torch ₂ =80°.

Example 4

Compared with Example 1, most of them are the same, except that in this example, the welding process parameters are controlled as:

The argon flow rate of the main welding torch 1 is 18L/min, and the argon flow rate of the auxiliary welding torch 2 is 18L/min; the current I _L of the main electrode is greater than the current I _T of the auxiliary electrode, I _L =180A, I _T =150A; the welding speed is 2.5～3m/min , the distance between the tip of the electrode and the workpiece 3 is 2.5mm, the distance between the electrodes is D=13mm, the inclination angle θ ₁ of the main welding torch 1 =78°, and the inclination angle θ 2 of the auxiliary welding torch ₂ =78°.

Example 5

Compared with Example 1, most of them are the same, except that in this example, the welding process parameters are controlled as:

The argon gas flow rate of the main welding torch 1 is 15-20L/min, and the argon gas flow rate of the auxiliary welding torch 2 is 15-20L/min; the main electrode current I _L is greater than the auxiliary electrode current I _T , I _L =210A, I _T =150A; welding speed 2.5 ~3m/min, the distance between the tip of the electrode and the workpiece 3 is 3mm, the distance between the electrodes is D=12mm, the inclination angle θ 1 of the main welding torch ₁ =76°, and the inclination angle θ 2 of the auxiliary welding torch ₂ =76°.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (7)

1. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate, which is characterized in that using electrode TIG to workpiece It is welded, two welding guns are connect with DC power supply, and definition is along welding direction, and the welding gun for being located at front is main welding gun, after being located at Welding gun supplemented by the welding gun in face, then in welding process, the main electrode electric current I on main weldering rifle_LMore than the auxiliary electrode electric current on auxiliary welding gun I_T, distance of the main electrode tip away from workpiece on main weldering rifle be less than or equal to the auxiliary electrode tip on auxiliary welding gun away from workpiece away from From, and main electrode and the space D of auxiliary electrode are 11~15mm.

2. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1, which is characterized in that main electricity Electrode current I_LWith auxiliary electrode electric current I_TRatio I_L/I_TIt is 1.2~1.5.

3. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1 or 2, which is characterized in that Main electrode electric current I_LFor 180~300A, auxiliary electrode electric current I_TFor 120~200A.

4. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1, which is characterized in that main electricity Pole and the tip of auxiliary electrode are away from being 2~4mm at a distance from workpiece.

5. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1, which is characterized in that welding In the process, the tilt angle theta of main weldering rifle₁=75 °~80 °, the tilt angle theta of auxiliary welding gun₂=75 °~80 °.

6. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1, which is characterized in that for The butt welding of the square groove of pure titanium TA2 material workpiece, welded gaps are controlled the 0~30% of thickness of workpiece δ.

7. a kind of High Efficiency Welding Process for titanium or titanium alloy thin plate according to claim 1, which is characterized in that welding In the process, the argon flow amount of main weldering rifle is 15~20L/min, and the argon flow amount of auxiliary welding gun is 15~20L/min.