Comparative study on girth weld-induced residual stresses between austenitic and duplex stainless steel pipe welds

Duplex stainless steel pipes find increasing use as an alternative to austenitic stainless steel pipes, particularly where chloride or sulphide stress corrosion cracking is of primary concern, due to the excellent combination of strength and corrosion resistance. During welding, duplex stainless steel pipes do not create the same magnitude or distribution of weld-induced residual stresses as those in girth-welded austenitic stainless steel pipes due to the different physical and mechanical properties between them. In this work, a comparison of the residual stresses between girth-welded austenitic and duplex stainless steel pipes was performed utilizing sequentially coupled three-dimensional thermo-mechanical finite element analysis method to accurately predict temperature fields and residual stress states in pipe girth welds. The results have shown that girth-welded austenitic stainless steel pipes produce much higher axial and hoop residual stresses normalized by the yield stress at the weld and its vicinity in which the welding start/stop effects are more significant and they have wider regions subjected to tensile or compressive stresses adjacent to the weld area.