During the surfacing welding of 304 stainless steel strip, several defects may occur. Some common defects include:
1.Porosity:
Porosity refers to the presence of small voids or gas pockets in the welded material. It can be caused by several factors such as inadequate shielding gas coverage, improper gas flow rate, contaminated base metal, or improper welding techniques. Porosity can weaken the weld and reduce its corrosion resistance.
2.Cracking:
Cracks can occur in the weld or in the heat-affected zone (HAZ). Cracking can be caused by various factors such as high heat input, rapid cooling, improper preheating or interpass temperature control, excessive residual stresses, or the presence of impurities in the base metal. Cracks can compromise the structural integrity of the weld.
3.Incomplete fusion or incomplete penetration:
Incomplete fusion occurs when the filler metal does not fuse completely with the base metal or adjacent weld beads. Incomplete penetration refers to a situation where the weld does not penetrate through the entire thickness of the joint. These defects can be caused by insufficient heat input, incorrect welding technique, or improper joint preparation.
4.Undercutting:
Undercutting is the formation of a groove or depression along the weld toe or adjacent to it. It can be caused by excessive current or travel speed, improper electrode angle, or incorrect welding technique. Undercutting can weaken the weld and lead to stress concentration.
5.Excessive spatter:
Spatter refers to the expulsion of molten metal droplets during welding. Excessive spatter can occur due to factors such as high welding current, incorrect shielding gas flow rate, or improper electrode angle. Spatter can result in poor weld appearance and may require additional post-weld cleaning.
6.Distortion:
Distortion refers to the deformation or warping of the base metal or the welded joint during welding. It can occur due to the non-uniform heating and cooling of the material, inadequate fixturing or clamping, or the release of residual stresses. Distortion can affect the dimensional accuracy and fit-up of the welded components.
To minimize these defects during surfacing welding of 304 stainless steel strip, it is important to follow proper welding procedures, ensure appropriate joint preparation, maintain proper heat input and shielding gas coverage, and use suitable welding techniques. Additionally, pre-weld and post-weld heat treatments, as well as non-destructive testing methods, can be employed to identify and mitigate potential defects.
Post time: May-31-2023