【作者】 张弦； 龚丽； 刘静； 成林； 吴开明；

【Author】 ZHANG Xian;GONG Li;LIU Jing;CHENG Lin;WU Kai-ming;Hubei Province Key Laboratory of Systems Science in Metallurgical Process,The State Key Laboratory of Refractory Material and Metallurgy,Collaborative Innovation Center for Advanced Steels,Wuhan University of Science and Technology;

【机构】 冶金工业过程系统科学湖北省重点实验室,耐火材料与冶金省部共建国家重点实验室,高性能钢铁材料及其应用省部共建协同创新中心,武汉科技大学；

【摘要】 采用精细表征方法(SEM/EDS、TEM、XRD、EBSD),电化学测试和慢应变速率应力腐蚀试验,研究经不同预应变(0.75/1/1.25δ_s)后,在海洋环境中残余奥氏体对微纳结构贝氏体钢的电化学及应力腐蚀开裂行为的影响。结果表明,随着预应变量的增加,试验钢中残余奥氏体的含量明显下降,发生了应力诱导马氏体相变,提高了钢的屈服强度和抗拉强度。经过预应变后,试验钢中空位和位错密度增加,表面活性位点的增加加速了钢的溶解;因此随着预应变量增加,微纳结构贝氏体钢的腐蚀电流密度增大,电化学腐蚀速率增大。通过预应变引入的大量位错,同时也阻碍了腐蚀促进的位错运动,使得腐蚀促进的局部塑性变形难以达到临界值,减少了应力腐蚀裂纹潜在的形核位点,改善了微纳结构贝氏体钢的应力腐蚀敏感性。更多还原

【Abstract】 Based on characterization methods(SEM/EDS,TEM,XRD,EBSD),electrochemical test and slow strain rate stress corrosion tests,the effects of retained austenite on the electrochemical and stress corrosion cracking behavior of micro/nano-structured bainitic steel were investigated in a marine environment after different pre-strains(0.75/1/1.25δ_s).The results showed that with increased pre-strain,the content of residual austenite decreased obviously,which indicated stress-induced martensitic transformation,leading to the improvement of yield strength and tensile strength of the steel.After prestrain,the vacancy and dislocation density in the steel increased,and the increased active sites on steel surface accelerated the dissolution of steel.Therefore,with the increase of pre-strain,the corrosion current density and electrochemical corrosion rate of micro/nano-structured bainitic steel increased.The large number of dislocations introduced by pre-strain also hindered the movement of corrosion induced dislocation,which made the local plastic deformation promoted by corrosion difficult to reach the critical value.Hence,the potential nucleation sites of stress corrosion cracks were reduced,resulting in the improvement of stress corrosion sensitivity of micro/nano-structured bainitic steel.更多还原