Sigma相对316不锈钢在熔融镁合金保护气中腐蚀行为的影响

Influence of Sigma Precipitation on the Corrosion Behavier of AISI 316 Stainless Steel in the Protection Gas for Molten Mg Alloy

选取了AISI316型奥氏体不锈钢在650-800℃范围内服役时间长达120 000h的管材,通过金相法和EDS分析证明了基材中含有Sigma相。主要研究了不锈钢中的Sigma析出相对AISI316型奥氏体不锈钢在熔融镁合金保护气(SF6)中腐蚀行为的影响。实验结果表明,含有Sig-ma相的316不锈钢实验到200h就发生了严重的晶间腐蚀。腐蚀产物中,首先形成Cr2O3然后连着CrxO3或CrxO4层,最表层是疏松的Fe3O4层与片状结构的Fe3O4和C混合层连接。

In this study the 316 stainless steel tube with a long-term thermal（650-800℃） exposure,up to 120 000 h,was selected as specimen.The sigma phases were confirmed in the substrate of tube by metallography and EDS.The influence of sigma precipitations in AISI 316 stainless steel was studies on corrosion behavior in the protection gas for molten Mg alloy.The results show that the intercrystalline corrosion occurred in the specimen after 200 h.The oxidation products of this stainless steel first formed a Cr2O3 layer followed by a volatile CrxO3 or CrxO4 layer.A porous Fe3O4 layer followed and a mixture of lamellar structure of Fe3O4 and C came next.