焊接方法对双相不锈钢焊接接头耐蚀性的影响

采用气体保护钨极氩弧焊（GTAW）、焊条电弧焊（SMAW）和埋弧焊（SAW）对2205双相不锈钢进行焊接，采用光学显微镜对接头组织进行观察，采用数点法计算铁素体相的含量，测定接头的耐点蚀和耐CO2应力腐蚀性能，研究焊接方法对接头耐蚀性的影响。结果表明，焊接方法影响焊缝组织形态及铁素体含量。GTAW焊缝由不规则的条状组织和两相交织分布的块状组织组成，而SMAW和SAW焊缝为方位不一的条状组织和少量的块状组织。GTAW和SMAW焊缝的铁素体含量为35％～55％，而SAW的不足20％。接头的耐蚀性与铁素体相比例密切相关，GTAW、SMAW和SAW的耐蚀性依次降低。从铁素体相比例和耐蚀性角度考虑，GTAW和SMAW能够获得满意的焊接接头。

Effect of welding process on corrosion resistance properties of duplex stainless steel welded joint

Duplex stainless steel 2205 was fabricated by gas tungsten arc welding （GTAW）, shielded metal arc welding （SMAW） and submerged arc welding （SAW） respectively. Microstructure was observed by an optical microscope, and the ferrite content was calculated using counting point method. Moreover, the pitting corrosion test and resistance to stress corrosion characterized by CO2 were measured to investigate the effect of welding process on the corrosion resistance properties of the welded joint. THe results show that the effect of welding process on the microstructure morphology of weld metal and the ferrite content is obvious. The weld metal with GTAW consists of both irregular strip microstructure and block microstructure with its two phases interleaving distribution, while the weld metal with SMAW and SAW is composed of a great amount of strip microstructure whose grain orientations are different and a small amount of block microstructure. The ferrite content of the weld metal with GTAW and SMAW is the range of 35% -55%, while that of the weld metal with SAW is lower than 20%. The corrosion resistance properties of the welded joint are related to the ferrite content. The corrosion resistance properties of GTAW are higher than that of SMAW, and that SMAW are higher than SAW. Considering the ferrite phase ratio and corrosion resistance properties, GTAW and SMAW are preferred.