Estimation of effectiveness of heat treatment modes for a welded joint by Sysweld software

The article presents the procedure to determine the field of residual stress after welding and heat treatment in a typical weld joint with FEM Sysweld software. Changes of steel elasticity and plasticity as a result of heating, as well as changes in the structural composition of steel in the process of welding and heat treatment, and speed and trajectory of welding were considered. Three different heat treatment modes used after welding have been examined: underannealing, normalization followed by air cooling, full annealing followed by slow cooling of the construction. The levels of residual stresses formed after welding and after each mode of heat treatment proved to be different as expected. The normalization and underannealing modes allowed to reduce considerably the level of residual stresses, however, the most effective heat treatment in terms of residual stress reduction is full annealing followed by slow cooling of the construction. The data analysis testifies that for the most effective reduction of residual stresses, the structural and phase recrystallizations are required that take place when the construction is heated above critical temperature Ас3.