中文摘要：

尝试利用小锥度试样测量304不锈钢应力腐蚀裂纹的形核时间，以确定裂纹形核在整个断裂过程中的贡献。结果表明，用小锥度试样可以有效测量应力腐蚀裂纹的形核时间。对304不锈钢，在沸腾MgCl2溶液中应力腐蚀裂纹的形核时间与应力之间满足ti=4310exp（-0.0097δ），而断裂时间与应力的关系为tf=6964exp（-0.0095a），说明应力腐蚀断裂时间的大部分来源于裂纹的形核过程、断口形貌与外加应力有关，随外加应力增大，断口的穿晶解理部分减少。

英文摘要：

In order to ascertain the contribution of crack nucleation process in fracture, round tapered specimens of 304 stainless steel were used to determine the initiation time of stress corrosion cracking in boiling 42 % MgCl2 solution. The results showed that the relation of the time to nucleation of stress corrosion cracking （SCC） to the applied stress obeyed t i= 4 310exp（ - 0. 009 7δ ） ; however, the relation of the time to fracture to the applied stress was t f=6 964exp（ -0. 009 5δ）. It was indicated that the majority of fracture process consisted of crack initiation. The fracture surface was related to the applied stress. The transgranular SCC area decreased with the increase in applied stress.