Alívio de tensões após soldagem

Abstract

The welding is one of the major joining processes of metallic materials. However, it causes macro and microstructural changes that affect the performance of the welded parts. Welding processes and techniques have been developed together with the development of the materials aiming to improving productivity and the quality of the final product. Despite this development there are still problems related to welding implementation. Residual stresses and distortion are formed during and after arc welding of a structure or component due to the concentrated heating of the joint. This causes localized temperature variations with the associated expansion and contraction of the metal in the weld region. These changes are restricted by the colder metal of the parts resulting in plastic deformation, residual stresses and distortion. Thermal and mechanical stress relief can be performed after welding, for instance by heat treatment (PWHT) and mechanical vibrations. Distortion can also be expected, controlled and corrected. For example, during the design phase, lower welding heat input may be specified, symmetrical grooves and more efficient welding processes may be selected. International codes and standards were created to direct the mechanical metal processing industry to sounder procedures from the design to the application of thermal treatment in welded equipment and structures. The present study aims to promote better understanding of the causes of residual stresses and distortion after welding and the different heat and mechanical treatments for residual stress relief of a welded structure.