S32101双相不锈钢焊接接头晶间腐蚀试验不合格原因

Cause of Failure in Intergranular Corrosion Test of S32101 Duplex Stainless Steel Welded Joint

为探究S32101双相不锈钢焊接后接头晶间腐蚀试验不合格的原因,对晶间腐蚀试验不合格的焊接接头进行了金相检验、X射线光电子能谱(XPS)分析和铁素体含量测试。结果表明:晶间腐蚀试验不合格的原因是材料存在化学成分偏析,造成铬的质量分数偏低,且焊接过程中在晶界处析出碳化铬,形成贫铬区,导致材料的抗晶间腐蚀能力降低。另外,显微组织中的铁素体含量偏低,也增加了贫铬区形成的可能性,进一步降低了抗晶间腐蚀能力。

In order to explore the reason of unqualified intergranular corrosion test of S32101 duplex stainless steel welded joint, metallographic examination, X-ray photoelectron spectroscopy(XPS) analysis and ferrite content test were carried out on welded joint which failed in intergranular corrosion test. The results show that the reason for the failure of intergranular corrosion test is that there is chemical composition segregation in the material, resulting in the low content of chromium, and chromium carbide precipitates at the grain boundary during the welding process, forming a chromium poor zone, which leads to the reduction of intergranular corrosion resistance of the material. In addition, the low content of ferrite in the microstructure also increases the possibility of the formation of chromium poor zone and further reduces the resistance to intergranular corrosion.