Inter-pass temperature effect on residual stress in multi-pass welding high strength low alloy steel

Welding one of the manufacturing processes used to make connections. Due to the high temperature of the welding and the non-uniform heat distribution, thermal stresses are created in the piece, which, after cooling the unit, are converted into residual stresses. Residual stress causes distortion, cracking, loss of buckling and failure strength, which generally affects the function and the life-time of the structure.Using the multi-pass and multilayer welding method, the heat required for welding is stepwise and timed to the piece, which can be prevented from entering the heat at once, and by controlling the inter-pass temperatures, the residual stress is reduced. In this research, multi-pass welding of high-strength low-alloy steel (DH36) plates using a numerical method with the help of ANSYS software has been investigated. This analysis was performed in three dimensions using the elemental birth and death technique. Two welding methods with gas metal arc welding are considered for the first two layers of the weld and submerged arc welding for the last three layers.Three different modes have been considered for inter-pass temperature values, each of which has been studied on the magnitude and distribution of residual stress. The results show that increasing the inter-pass temperature reduces the maximum magnitude of residual stress and also increases the distribution area of residual stress in the area of maximum residual stress.

Keywords:

Welding , Multi-pass Welding , Residual Stress , Inter-pass Temperature