Effect of ageing time on the creep behaviour of NiAl hardened austenitic stainless steel

Abstract

The effect of ageing time at 973 K on creep deformation and fracture behaviour of a model NiAl hardened austenitic stainless steel was studied. The creep behaviour of the alloy aged for 5, 15 and 50 h at 973 K differed considerably at high stresses while it was fairly matching at low stresses. Such a behaviour was attributed to stress dependent change in dislocation by-pass mechanism from Orowan bowing or particle shearing in the high stress regime 10 climb over particles in the low stress regime. Experimental creep rupture data for all the three ageing times followed modified Monkman-Grant relation indicating that fracture and thereby time-to-rupture is controlled by power- law growth of cavities.