TP316L stainless steel pipe horizontal fixed welding is a weld in all positions. Therefore, welding is more difficult. To prevent the internal weld seam from sinking into the aerial weld, we use the aerial welding part (60o on each side of the six points) to fill the wire, and the vertical and flat welding. parts to fill the wire for welding. Before starting the arc, fill the tube with argon gas to replace the air in the tube before welding. During the welding process, the welding wire should not touch the tungsten electrode or penetrate directly into the arc column area of the arc, otherwise it will cause tungsten in the weld and damage the arc stability The end should not be removed from the protection area to prevent oxidation and affect quality. Welding starts at 5 mm after 6 y'clock. No matter where the weld is located, the tungsten electrode must be perpendicular to the tube shaft. This can better control the size of the cast pool and make the nozzle evenly protect the melted pool. oxidation. When welding, the distance between tungsten tip and weld is approximately 2 mm. The weld wire must be sent to the front end of the cast bath along the tangent point of the pipe along the groove, and the weld wire is melted by the high temperature of the melting pool. After the arc is turned on, preheat at one end of the slot. After the metal melts, send the first drop of welding wire to melt the metal, and then the arc swings to the other end of the groove and sends the second drop of welding wire to melt the metal, so that the two drops of cast iron come together to form a weld. The base of the seam, then the arc swings laterally, remaining on both sides for a while, the welding wire is uniform and intermittent fed into the molten pool to weld forward.
Causes and prevention of common defects in TP316L stainless steel pipes A small welding current, a small root space, excessive welding speed, abnormal torch angle, etc. are easy to produce incomplete penetration defects. The root space should not be less than 3.5 mm The proper welding current and the correct adjustment of the welding gun angle can prevent incomplete penetration. When oxidation is severe, the pressure device in the pipe does not provide good protection and the back of the weld will oxidize; the cast bath and end of the weld wire will be poorly protected during the welding process, or impurities on the weld wire surface will also be seriously oxidized. The oxygenation device should be as close to the pipe as possible and no space should be left The space between the pipe should be glued with high temperature resistant aluminum foil to prevent weld oxidation. In the slag and tungsten welding process, if the end of the weld wire leaves the argon protection zone during the high temperature process, it will oxidize in the air. When re-welding, the end of the rusted wire is not cleaned and In the fracture test, it was considered to be an inclusion of slag; If the length of the tungsten electrode is too large, the welding torch action is unstable and the weld is not finished after the tungsten electrode and welding The tungsten wire or electrode and molten bath collide, resulting in the inclusion of tungsten. Because the tube is round, the welding torch and wire feed angle must be changed at any time, so the technique should be stable and accurate to prevent the inclusion of slag and tungsten. The concave assembly space is small and the welding torch oscillates a lot during the welding process, so the arc heat cannot be concentrated at the root, resulting in a concave phenomenon in which the rear weld seam is lower than the surface of the test part. Arc heat is concentrated at the root as much as possible, and more spot welding wire is used in the welding position above the head to avoid concave.
