① Porosity, hot wire: During TIG welding, pores will occur when there are oil, rust, moisture and other impurities on the surface of the pipe or welding wire, the argon gas flow rate is improperly selected, the protection effect is poor, or the welding heat input is too small. Therefore, before welding, it is necessary to strengthen the cleaning of the inner and outer walls of the pipe and the welding wire, and determine the appropriate arc length to ensure that the welding area is within the Ar gas protection range.

② Burn-through, when hot wire TIG welding, the selected welding current is too large, the welding speed is too slow, the gap at the root of the weld groove is too large, the arc stays at the weld for too long, etc. may form perforation defects - Burn through. Therefore, minimizing the assembly gap at the root of the weld before welding, choosing a smaller welding current and matching the appropriate welding speed can reduce the chance of weld burn-through.

③ Undercut, when hot wire TIG welding, the selected welding heat input is too large, the welding gun swing frequency or the welding gun residence time on both sides is improperly selected, the arc is too long, and the arc magnetic blow during DC welding may occur along the weld. The toe forms a depression or groove in the base material, which is called an undercut. Therefore, strengthening the workpiece surface cleaning before welding, matching the welding current of the cover weld to the appropriate welding speed, determining the appropriate welding gun swing frequency and the welding gun residence time on both sides are all measures that can effectively prevent the occurrence of undercuts.

④ Incomplete penetration, hot wire TIG welding adopts the typical single-sided welding and double-sided forming form. The selected welding heat input is too small, the arc is too long, the weld groove angle is too small, and the blunt edge is too thick. It is easy to form insufficient welding meat or incomplete welding defects on the back side of the weld. Therefore, increasing the welding current to match the appropriate welding speed, increasing the weld bevel angle, thinning the blunt edge, appropriately increasing the assembly gap, etc. can reduce the possibility of incomplete welding defects.

⑤ External surface defects. During hot wire TIG welding, due to improper matching of welding specifications, it is easy to form surface defects such as pits, incomplete welding, and excessively high weld reinforcement on the outer surface of the weld. Most of the pits are caused by the current attenuation function not being used when closing the arc. Insufficient filler metal and too weak specifications may form continuous or intermittent grooves on the surface of the weld, which is often said to be under-welded. If the welding speed is too slow or the pipe rotation speed does not match the welding gun swing speed, it is easy to cause the reinforcement layer on the surface of the weld to be excessively convex. Correctly selecting the appropriate welding current, matching the welding speed to the pipe rotation speed and the welding gun swing speed, and using the current attenuation function when closing the arc can effectively prevent surface defects such as incomplete welding and excessively high weld reinforcement.