DP-TIG焊接工艺对316L不锈钢搭接接头耐腐蚀性能的影响

Effect of DP-TIG Welding Process on Corrosion Resistance of 316L Stainless Steel Lap Joint

本文采用DP-TIG焊接技术对316L不锈钢进行搭接试验,研究了焊接电流和焊接速度对搭接接头的金相显微组织及耐腐蚀性能的影响,并用扫描电镜分析了腐蚀后试样的表面形貌。结果表明,随着焊接电流的增大、焊接速度的降低,焊缝中残余铁素体组织减少,接头的耐腐蚀性能提高;焊接接头的极化曲线及阻抗谱结果表明,焊接电流为170A、焊接速度为280mm/min时,接头表现出较好的耐腐蚀性能,焊接电流对接头耐腐蚀性能的影响大于焊接速度对其的影响;试样腐蚀形貌扫描电镜结果显示,蚀坑主要产生于铁素体晶粒内部或晶界处,并沿着铁素体相界扩展腐蚀,随着蚀坑的长大最终引起结构失效。

In this paper,DP-TIG welding technology was used to perform lap test on 316L stainless steel,the effects of welding current and welding speed on the metallographic microstructure and corrosion resistance of lap joints were studied,and the surface morphology of the corroded specimens was analyzed by scanning electron microscopy.The results showed that the residual ferrite structure in the weld decreased and the corrosion resistance of the joint increased with the increase of welding current and the decrease of welding speed.The polarization curve and impedance spec-trum results of the welded joint showed that when the welding current was 170 A and the welding speed was 280 mm/min,the joint showed good corro-sion resistance,and the influence of welding current on the corrosion resistance of the joint was greater than that of the welding speed.The results of scanning electron microscopy of the corrosion topography of the specimen showed that the pit mainly occurred in the interior or grain boundary of the ferrite,and extended corrosion along the ferrite phase boundary,and eventually caused structural failure as the pit grew.