Abstract: Subs critical crack growth behavior in 310 steel was studied under creep condition at the temperature of 600～800℃ and the initial not section stresses of 11.8～56.8MPa. The crack length was measured by a D.C. electrical potential drop technique in CT-specimens. The fracture surfaces were observed by scanning microscope. The results show that the apparent activation energy of crack growth decreases and the fracture mode changes from intergranular to intragranular with the increase of crack length. The secondary load point displacement rate has the characteristics of minimum creep rate and can represent the local creep rate in front of crack tip. The relation of the initial net section stress with Larson-Miller parameter is similar to that of stress with Larson-Miller para meter in creep test.

Key words: 不锈钢, 裂纹扩展, 蠕变