第二相析出对Cr-Ni系粉末冶金不锈钢耐蚀性的影响

Effect of second phase precipitation on corrosion resistance of powder metallurgy Cr-Ni stainless steel

为研究提升Cr-Ni系粉末冶金不锈钢阀座的耐腐蚀性能,设计在阀座零件中添加元素Ti和Nb,并采用固溶处理、稳定化处理、固溶＋稳定化处理3种不同的工艺路线进行热处理试验。结果表明：1080℃保温1 h后水冷固溶处理,然后再配合880℃保温6 h稳定化处理的热处理工艺可以有效改善其耐腐蚀性能,防锈性能达到72 h中性盐雾腐蚀试验要求;通过扫描电镜和EDS能谱等手段发现,粉末冶金不锈钢中Cr（23）C6等铬的碳化物是导致其耐腐蚀性能下降的重要原因,而钎焊会加剧Cr（23）C6等铬的碳化物的析出,进一步降低其耐腐蚀性。固溶＋稳定化处理工艺可以有效减少有害物Cr（23）C6析出,有效改善Cr-Ni系粉末冶金不锈钢零件的耐腐蚀性能。

In order to improve the corrosion resistance of powder metallurgy Cr-Ni stainless steel,elements of Ti and Nb had been designed to add to the steel,as well as three different heat treatment processes of solution treatment,stabilizing treatment,and solid treatment＋stabilizing treatment were experimented.The results shown that after 1080℃×1 h solid solution and 880℃×6 h stabilizing the corrosion resistance of powder metallurgy Cr-Ni stainless steel is remarkably improved so that it could tolerate the salt spray corrosion test for 72 h.Through scanning electron microscopy（SEM）and energy disperse spectroscopy（EDS）methods,it is found that harmful carbide such as Cr（23）C6 in the steel is the important cause of the deterioration of corrosion resistance.In addition,brazing intensifies the precipitating of Cr（23）C6,so that further reduces the corrosion resistance of the steel.Uniting solid solution treatment with stabilizing treatment can lessen the precipitating of Cr（23）C6 effectively,so as the corrosion resistance of the powder metallurgy Cr-Ni stainless steel is improved effectively.