改性纳米SiC粉体强化铸造奥氏体不锈钢耐点蚀性能的研究

PITTING CORROSION RESISTANCE OF NANO-SiC POWDERS REINFORCED CAST STAINLESS STEEL

在生产条件下采用冲入法制备了改性纳米SiC粉体强化奥氏体不锈钢试样,用化学浸泡和电化学检测两种方法研究了纳米SiC粉体对不锈钢耐点蚀性能的影响。结果表明,经改性纳米SiC粉体强化处理后的不锈钢组织明显细化,成分偏析引起的铁素体析出减少;当纳米SiC粉体加入量为0.1 mass%时,不锈钢的点蚀速率降低了16%,电极电位提高了3倍。能谱分析表明,经强化处理,不锈钢中的Cr成分偏析减轻,有效改善了晶界等易发生点蚀部位的贫Cr现象。

Cast austenitic stainless steels reinforced by modified SiC nano-powders have been prepared with pour over process under industrial conditions, and the effect of modified SiC nano-powders on the pitting corrosion resistance of the austenitic stainless steel was characterized by pitting chemistry immersion and pitting electrochemistry tests, metallographic analysis, SEM and energy dispersive analysis. The results showed that, compared with the samples without SiC nano-powders, the reinforced stainless steel was characterized with finer microstructure, and less ferrite precipitation owing to composition segregational the pitting corrosion velocity had decreased by 16% and the electric potential increased by three times respectively when the content of nano-SiC rose to 0.1 mass%. Furthermore, the results of energy dispersive analysis of samples with the scanning electron microscopy revealed that the Cr segregation in the reinforced austenitic stainless steels reduced, and the Cr depletion in such zones sensitive to pitting corrosion as grain boundaries has been improved.