How Do I Go about Welding Titanium?

Common welding methods for titanium and titanium alloys are: argon arc welding, submerged arc welding, vacuum electron beam welding, etc. Tungsten arc welding is used for thicknesses below 3 mm, and TIG welding is used for thicknesses above 3 mm. The purity of argon is not less than 99.99 , and the content of air and water vapor in argon is strictly controlled. Before welding, degreasing, descaling, and oxide film surface treatment are performed. Because titanium and titanium alloys have high chemical activity and are easily contaminated by oxygen, nitrogen, and hydrogen, electrode welding, oxyacetylene (or oxypropane, etc.) gas welding, C02 welding, and atomic hydrogen welding cannot be used.

Titanium alloy welding

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Common welding methods for titanium and titanium alloys are: argon arc welding, submerged arc welding, vacuum electron beam welding, etc. Tungsten arc welding is used for thicknesses below 3 mm, and TIG welding is used for thicknesses above 3 mm. The purity of argon is not less than 99.99 , and the content of air and water vapor in argon is strictly controlled. Before welding, degreasing, descaling, and oxide film surface treatment are performed. Because titanium and titanium alloys have high chemical activity and are easily contaminated by oxygen, nitrogen, and hydrogen, electrode welding, oxyacetylene (or oxypropane, etc.) gas welding, C02 welding, and atomic hydrogen welding cannot be used.

Chinese name

Titanium alloy welding

Content one

Effect of titanium characteristics on titanium welding

Content two

Weldability of titanium and titanium alloys

Content three

Titanium and titanium alloy welding process selection

Content four

Surface color of titanium and titanium alloy welding interface

1. Preparation before welding

The surface quality of the weldment and titanium wire has a great influence on the mechanical properties of the welded joint and must be cleaned strictly. Iron plate and titanium welding wire can be mechanically and chemically cleaned.

1.1 Mechanical cleaning butt welding Welding parts with low quality requirements or difficult pickling can be wiped with fine sandpaper or stainless steel wire brush, but it is best to scrape the titanium plate with a yellow hard alloy to remove the oxide film.

1.2 Chemical cleaning. Before welding, the test piece and welding wire can be pickled. The pickling solution can be HF5% + HNO335% water melt. Rinse with clean water after pickling and apply welding immediately after drying. Or use acetone, ethanol, carbon tetrachloride, methanol, etc. to wipe the groove of the titanium plate and its two sides (within 50mm each), the surface of the welding wire, and the parts in contact with the titanium plate.

2. Selection of welding equipment For argon arc welding of titanium and titanium alloy gold-tungsten plates, a DC argon arc welding power source with falling external characteristics and high-frequency arc initiation should be used, and the delay time of gas delivery should be not less than 15 seconds to avoid welding from being oxidized. ,Pollution.

3. Selection of welding materials The purity of argon gas should not be less than 99.99%, the dew point should be below -40 , and the total mass fraction of impurities & lt; 0.001%. When the pressure in the argon cylinder drops to 0.981MPa, it should be stopped to prevent affecting the quality of the welded joint. In principle, titanium wire with the same composition as the base metal should be selected. Sometimes, in order to grasp the plasticity of the weld metal, a wire with a lower strength than the base metal can also be selected.

4. Gas protection and welding temperature Titanium pipe joints are grounded during welding. In order to prevent the welded joints from being contaminated by harmful gases and elements at high temperatures, the necessary welding protection and temperature control must be performed on the weld zone and the weld. The temperature should be 250 Below . The main methods of protection and temperature control are: one is to add a protective gas mop to the surface welds; the other is to fill the welded tube with protective gas. The protective gas is argon, and its purity should be 99.99%. The flow of shielding gas should meet the requirements of welding technology

5.Selection of welding parameters

5.1 Titanium alloy welding wire. The grade of the filler wire should be selected according to the base material. Generally, the principle of homogeneity with the base material is used. Sometimes in order to improve the plasticity of the joint, a wire with a lower alloying degree than the base material can also be selected. The diameter of the welding wire should be selected according to the thickness of the base metal (see Table 2) Table 2

5.2 Tungsten electrode. It is best to choose cerium tungsten electrode, whose diameter is selected according to the thickness of the titanium alloy tube wall, generally in the range of 1.0 to 3.0 mm, and the tungsten extreme part should be ground into a cone of 30 to 45 degrees.

6. The selection principle of the bevel form minimizes the number of welding layers and welding metal. With the increase of the number of welding layers, the cumulative suction set of the weld seam increases, which affects the performance of the welded joint. Because the size of the weld pool is larger when titanium and titanium alloys are welded, the test specimen is V-shaped 70 ~ 80 ° groove .

7. Test piece group butt welding In order to reduce welding deformation, tack welding is performed before welding. Generally, the tack welding distance is 100 ~ 150mm and the length is 10 ~ 15 mm. The welding wire, welding process parameters and gas protection conditions used for tack welding should be the same as those used for welding joints. Clearance 0 ~ 2mm, blunt edge 0 ~ 1.0mm.

1.Weld zone

Silver white, light yellow (allowed for first, second and third grade welds); dark yellow (allowed for second and third grade welds); golden purple (allowed for third grade welds); dark blue (first, second and third grade welds) Are not allowed).

2.Heat affected zone

Silver white, light yellow (allowed for first, second and third grade welds); dark yellow, golden purple (allowed for second and third grade welds); dark blue (allowed for third grade welds).

1. During manual argon arc welding, the minimum angle (10 ~ 15 °) between the welding wire and the weldment should be kept as far as possible. The welding wire is smoothly and uniformly fed into the welding pool along the front end of the welding pool, and the end of the welding wire must not be moved out of the argon protection zone.

2. When welding, the welding torch basically does not make lateral swing. When swing is required, the frequency should be low and the swing amplitude should not be too large to prevent affecting the protection of argon.

3. When the arc is broken and the welding seam is closed, argon gas protection should be continued until the welding seam and the heat-affected zone metal cools below 350 ° C before removing the welding torch.