Welding induces various types of distortion such as longitudinal shrinkage, transverse shrinkage, angular distortion and so on, which are result of the non-uniform expansion and contraction of the weld and surrounding base material caused by the heating and cooling cycle during welding process. Welding distortion has negative effects on production efficiency, accuracy of assembly, external appearance and various strengths of the welded structures such as carrying capacity. In many cases, additional costs and schedule delays are incurred from straightening welding-induced distortion. For these reasons, prediction and control of welding-induced distortions have become of critical importance.