Angular distortion
Angular distortion is a shape change in welded sheets that angle relative to each other. It occurs due to uneven thermal shrinkage across the cross-section.
Physico-chemical mechanism
Angular distortion happens when the face of a plate cools off faster than the inside. The uneven shrinkage as it cools pulls the plates out of square.
Metallurgical relevance & welding risks
Angular distortion can build up stress and lead to cracks. It also throws off the load distribution, which messes with the grain structure. In the worst cases, you can get sudden breaking.
Shop practice & how to handle it
To avoid angular distortion, you need even cooling. Use a cooling bar or a heat sink to pull heat out of both the face and the underside at the same time. Don't let the plate bend too much while welding. For heavy jobs, preheating the plate or using a chill strip can help.