A COMPARATIVE-STUDY OF CREEP-RUPTURE BEHAVIOR OF MODIFIED 316L(N) BASE-METAL AND 316L(N) 16-8-2 WELDMENT IN AIR AND LIQUID-SODIUM ENVIRONMENTS/

Creep rupture behaviour of modified type 316L(N) stainless steel base metal and weldments prepared with 16-8-2 filler wire has been investig ated in air and flowing sodium environments at 823 K. No adverse envir onmental effects have been noticed due to sodium on the creep rupture behaviour of these weldments for tests up to 10 000 h. Rupture lives o f the weldment were higher in the sodium environment than those in air . Rupture lives of the weldments were found to be lower than those of the base metal by a factor of two to five in both air and sodium envir onments. Minimum creep rates were essentially the same for the weldmen t as well as for the base metal in both the environments, whereas rupt ure strain was usually lower for the weldment than that of the base me tal. The reduction in area of the weldment specimens increased with in crease in stress. Failures in the specimens of weldments were in the w eld metal region. Microstructural studies carried out on failed weldme nt specimens after the creep rupture tests revealed extensive cavitati on in the weld metal region in air tested specimens predominantly at t he austerite/delta-ferrite interphase. However, no cavitation was obse rved in specimens tested in sodium. (C) 1997 Elsevier Science Ltd.