GRAIN-SIZE DEPENDENCE OF CREEP CRACK-GROWTH IN NI-CR AUSTENITIC STEELS

From single phase to two-phase alloys, creep crack growth behavior of Fe-15Cr-25Ni austenitic steels has been examined for different grain s izes at 973 and 1123 K. The creep crack growth rate increases with inc reasing grain size. An equation was found to describe the relation bet ween the initiation time t(i) or rupture time t(r) and grain size d: t (r(i)) . d(beta) = C. The precipitation of grain boundary carbide decr eases the effect of grain size on creep crack growth. Different grain size dependences on creep crack growth in other materials were also an alysed. A damage model based on constrained cavity growth was shown to provide good predictions on the grain size effect on creep crack grow th behavior.