Numerical simulation of stress & strain field of stress-free and non-deformation post-heating following welding

The stress & strain fields of low alloyed steel plate welded by two processes, normal arc welding and post-heating following welding (PHFW), are calculated with FEM. The stress distribution and warp deformation along middle cross-section caused by the two welding methods are compareal. It shows that the maximal longitudinal residual stress is only 13MPa with the latter method, in which the whole cross-section being tangential to 600°C isothermal curve is heated to 605~620°C, and then the whole plate is cooled naturally. A moving cover plate with same width as plate following welding torch is applied to control transient deformation in the latter method. The maximal warp deformation along middle cross-section is only 0.23mm, which is far lower than that, 3.7mm, with normal welding. It is much lower than that of DC-LSND welding method. PHFW is a stress-free and non-deformation welding process.