Influence of sodium environment on tensile behaviour of Aisi type 316 stainless steel in solution annealed, cold rolled and as-welded conditions

The tensile specimens of AISI type 316 stainless steel in solution annealed and cold rolled conditions (20% reduction in thickness) have been exposed to liquid sodium for a period of 10,500 hours in a thermal convection loop at temperatures of 643, 683 and 723 k. The results of tensile tests on solution annealed samples showed increase in YS and UTS and loss of reduction in area and elongation. Loss of ductility was more for samples exposed at higher temperatures. The results of cold rolled samples showed an opposite behaviour i.e. loss in YS and UTS and gain in total elongation. However, the reduction in area was lower for sodium exposed samples. Loss of reduction in area was more for samples exposed at higher temperatures. In another set of experiments where solution annealed AISI 316 stainless steel and its weldments were exposed to flowing sodium at 773 k for 5500 hours, the exposed specimens showed increase of about 20% in yield strength. No significant change in UTS and elongation was found