Investigation of transient/residual strain and stress in dissimilar weld

Abstract

Optimizing welding parameters to achieve low residual stress (RS) with the aid of stress reduction techniques usually relies on the study of residual strain distribution in weldment. However, investigating transient strains using experimental methods such as strain gauges gives an additional view on how RS is reduced. In this work, the transient strain and stress on the surface of dissimilar plate during gas-tungsten arc (GTA) welding process have been studied using non-destructive strain gauge method. It is demonstrated that strain gauge measurements during dissimilar welding processes can be used to indicate residual elastic strain and stress. Moreover, three- dimensional (3D) finite element (FE) model has been developed and verified with experimental work (neutron diffraction measurement), and was employed to examine the formation of RS upon cooling of a 304-1018 dissimilar weldment. The strain gauge (SG) measurement method shows good agreement with FE model and neutron diffraction measurements. The assumptions and limitations associated with strain measurement and determination of the stress state are explored. Lastly, curvature due to dissimilar weld and its effects on strain measurement, which is in contrast with similar weld, was measured and discussed.