Analysis for toughness of 2205 duplex stainless steel pipe welds

2205 duplex stainless steel possesses favorable mechanical properties and good corrosion resistance, and is applied wildly in transport, oil and natural gas, ocean and chemistry industry, etc.Compared to general austenitic stainless steel, duplex stainless steel is its difficult to weld.One natural gas the maximum operation pressure in one collection pipe of natural gas trausport is 13.3 MPa and still generally considered as material which are minimum operation temperature is -30℃, and very high toughness was required for the pipe welds.The Charpy impact toughness and fracture toughness(CTOD)of longitudinal welds (used SAW methods) and girth welds (used GTAW +SMAW methods) of 2205 duplex stainless steel pipe used for high pressure nature gas transport were tested and analyzed.The results show that the impact toughness and fracture toughness of longitudinal welds is better than that of the girth weld markedly.The main reason of these results is concern with difference of filler metal and microstructure phase ratio caused by difference heat input and postweld heat treatment.