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Key points for welding titanium pipe fittings!
Key points for welding titanium pipe fittings!

1. When welding titanium pipe fittings, due to the protective gas support cover, the welding gun swing is inconvenient and inflexible, which is prone to defects such as dents in the weld seam, undercuts on both sides, and incomplete fusion. The welding of the rear cover is generally not easy to collapse, so it is ensured to use a reamer to screw the joint out of the slope for the convenience of the joint. The backing layer is generally welded using the upward welding position wire filling method and the vertical and horizontal welding position external wire filling method. If the upward welding joint is not well controlled, concave defects are prone to occur. When welding a joint, the welding wire should be sent after the fusion hole appears. To avoid joint depression, more welding wire can be added to the first two drops. Afterwards, the welding should be carried out in a normal manner, and the gas flow rate of the traction cover should be 30-40L/min.

2. When welding, the welding wire should be sent to the front end of the molten pool along the groove and pipeline cutting point, and the high-temperature melting of the welding wire in the molten pool should be utilized. The angle between the welding gun and the welding wire should be maintained well, ranging from 80 ° to 1009 °. Especially, the inclination angle between the welding wire and the pipe groove should not be too small, otherwise the welding wire may easily stick to the welding groove, which is not conducive to the feeding of the welding wire. During the welding process, the welding wire should not come into contact with the tungsten electrode or directly penetrate into the arc column area of the arc, otherwise it may cause tungsten inclusion in the weld and damage the stability of the arc.

3. When welding at any position, the tungsten electrode should be perpendicular to the axis of the titanium pipe fitting, which can better control the size of the molten pool and ensure that the nozzle and tail cover protective gas evenly protect the molten pool from oxidation. According to the length of the protective cover, stop welding when the welding length is generally 100mm, and continue welding after the weld changes from red to silver white. When observing the color of the weld seam, do not remove the tail cover or observe from the front of the tail cover. It is better to observe from the back of the tail cover. The interlayer temperature should be below 50 ℃, and it is better to touch the weld seam with your hands instead of using hot hands. After the welding joint cools down, it is better to perform secondary welding. In emergency situations, cold air can be used to blow the weld seam, or wet cloth can be used to wipe both sides of the titanium pipe weld seam. Be careful not to wipe the weld seam.

4. When stopping welding, the arc crater should be filled up and gas delay protection with a welding gun and traction cover should be used to prevent the weld from being polluted by air at high temperatures, making the weld color qualified. The end of the welding wire should not be pulled out of the protection zone in a timely manner. Otherwise, the end of the welding wire will immediately discolor and oxidize, and cannot be used continuously. If it needs to be used again, the oxidation end should be cut off with pliers before use.

5. Grind the end into a slope shape. When welding on the slope, the wire feeding should be suspended. Use an arc to melt the slope into a melting hole, and quickly add welding wire to seal the weld. Note that when the two semicircles are less than half, the internal protective gas flow should be reduced to prevent the weld from sinking due to high air pressure.

6. Poor gas protection, prone to gas pores, brittle hard structures, and brittle fractures. The silver white of titanium pipe fittings' welds and heat affected zones is better, while the yellow color is worse, and the blue color is not qualified.