Numerical simulation of welding and quenching processes using transient thermal and thermo-elasto-plastic formulations

A comprehensive methodology for the analysis of residual stresses due to welding and quenching processes is detailed using the finite element method. The non-linearities due to the variation of material properties and heat transfer coefficients with temperature and those due to the inclusion of a radiation boundary condition and solid phase transformation effects are considered in the thermal and thermo-elasto-plastic formulations. The combined isotropic and kinematic hardening model takes care of the Bauschinger effect due to cyclic (thermal) loading involved during these processes. Constitutive equations, with von Mises yield criterion and the associated flow rule, as derived from generalized plastic flow theory, are used. Limitations on the usability of some commercial finite element codes, especially for including thermal effects due to phase transformation and transformation plasticity, are highlighted. Some case studies like butt welding of plates, circumferential welding of pipes, multi-pass welding of plates and quenching are included for testing the computer programs developed. The temperature and stress distributions obtained during these analyses are compared with the results available for these problems in the literature. Experiments are conducted for the butt welding of plates and the theoretical temperature and residual stress distributions are compared with the measured values. Copyright (C) 1996 Elsevier Science Ltd