Creep deformation and fracture behaviour of a nitrogen-bearing type 316 stainless steel weld metal

Creep properties of a nuclear grade type 316 stainless steel (SS) weld meta l containing similar to 0.08 wt% of nitrogen were studied at 873 and 923 K. These properties were compared with those of a type 316 SS weld metal with out nitrogen. In general, the nitrogen-bearing weld metal exhibited better creep and rupture properties. The rupture strengths of the nitrogen-contain ing weld metal was similar to 40% higher than that for the type 316 SS weld metal at both the temperatures. The steady-state (minimum) creep rates wer e up to two orders of magnitude lower for the nitrogen-containing weld meta l compared to 316 SS weld metal. Rupture ductility of nitrogen-containing w eld metal was lower at all the test conditions; the long-term ductility at 923 K was below 5%. The differences in creep behaviour of the two weld meta ls are discussed with respect to the influence of nitrogen on microstructur al evolution in the two weld metals. (C) 1999 Elsevier Science B.V. All rig hts reserved.