Points of argon arc welding of titanium alloy pipes

Titanium alloy pipe welding is usually on-site all-position welding, the difficulty is much higher than stainless steel pipe welding, titanium and its alloys above 400 ℃ weld zone must be protected, because of its chemical nature is particularly active, it is easy to absorb harmful gases, resulting in a decline in the performance of the material, and even cracks. Therefore, welding should pay special attention to the following matters.

In welding titanium and its alloy pipe, welding consumables selection basically to the principle of equal strength, can not find suitable welding consumables, can be used from the base material on the cut to solve the problem; and the choice of argon will have a direct impact on the hardness and toughness of the weld, on the welding cracks have a significant impact, so the choice of selection (especially pure titanium) high purity argon gas (99.99%).

Titanium tube cutting and rupture production should be used cold processing methods, shall not make it overheating and discoloration. In the bevel inside and outside the surface of not less than 20mm range with a grinding wheel or stainless steel wire wheel to polish out the metal luster, with a scraper to trim the bevel of the burr and then polish smooth, to avoid hanging on the cleaning of the cloth wire.

The quality of cleaning directly affects the welding cracks and porosity, usually the first use of pickling (3% HF + 35% HNO3 + H2O), and then rinsed with water, and finally dry, wipe with acetone or alcohol before welding. After cleaning the weld must be welded immediately, not more than 4h, or need to be re-cleaned. Cleaning can not use rubber gloves, should use white cotton gloves.

Titanium alloy pipe welding area protection is critical, and stainless steel pipe welding is similar, but the requirements of gas protection are more stringent, tube filled with argon to continue to the end of the welding until the temperature of the welded area is down to 350 ℃ can stop; tube outside the front of the argon protection using a large-diameter nozzle and the use of lengthened towing cover, in order to improve the protective effect, when the welding is over, the towing cover is not the end of the must wait for The temperature drops to below 200℃ before stopping the gas supply and removing the drag shield.