材料期刊网

<正> 一、前言 船体钢在海水中的腐蚀疲劳是船舶结构破坏的主要形式。设计舰船壳体阴极保护系统时通常着眼于防腐蚀效果,并不考虑对船体结构强度的影响。已有的研究资料指出,阴极保护可提高光滑试佯的腐蚀疲劳强度,但对疲劳裂纹扩展速率影响的看法存在分岐。有人认为,阴极保护加速疲劳裂纹扩展;也有人认为,在一定条件下阴极保护会阻碍疲劳裂纹扩展。本工作在实验室条件下研究介质和阴极保护电位对长、短疲劳裂纹扩展行为的影响。 二、材料及试验方法 试材采用调质态12CrNi3MoV钢,化学成份见表1,机械性能见表2。

The long and short fatigue crack growth(FCG) of 12CrNi3MoV steel was investigated under cathodic protection(CP) in 3.5％NaCl solution. The results indicated that the long FCG was different from the short one in brine and under cp. In salt water, the short FCG rate increased while the long FCG rate decreased. The short FCG was apparently hindered at appropriate CP potential (—900mV, SCE) and accelerated at over-protection potential (—1200mV, SCE). On the contrary, CP increased the long FCG rate and the more negative the CP potential, the greater was the long FCG rate. The short FCG rate was greater than the long one at the same ΔK and the difference increased in salt water, but decreased under CP. Finally the oxygen trans-portation, the wedging of corrosion products and the hydrogen embrittlement effect in both long and short crack tips were discussed.