INVESTIGATIONS INTO EFFECT OF RESIDUAL STRESSES ON MECHANICAL BEHAVIOUR OF DUPLEX STAINLESS STEEL WELD JOINT

Duplex stainless steel alloy is widely used in the manufacture of pressure vessels, nuclear plant, chemical refineries and paper mill. Welding is the most preferred fabrication method in these structural applications; however during welding, the work piece is subjected to thermal cycle, as a result residual stresses are developed in the weld. Residual stresses have significant effect on performance of the weld joint subjected to tensile loading. In addition to this duplex stainless steel is welded using strength over matched filler material. Thus, the weld joint consist of two different materials having different behaviour under tensile loading. This paper presents a method to model mechanical behaviour of weld joint in the presence of residual stresses using deformation theory of plasticity. The results show that deformation theory of plasticity can be used to model post yield behavior of a weld joint. As expected stress-strain behavior of the weld joint differ marginally from virgin duplex stainless steel alloy. The work presented in this paper will help designer to ensure structural integrity.