超级双相不锈钢多层多道焊接接头组织及腐蚀性能

选用2507超级双相不锈钢作为研究对象，研究钨极氩弧焊多层多道焊接接头的组织和腐蚀性能.采用两种不同保护气进行钨极氩弧焊，主要讨论焊接道次和氮气添加对组织和腐蚀性能的影响.结果表明，焊缝中心均有较高的奥氏体含量，其腐蚀速率是焊根部位的0.68倍；盖面和焊根奥氏体含量相近，但盖面由于其弥散且尺寸相对较大的晶内奥氏体表现出更好的耐腐蚀性，焊根是焊缝金属的薄弱区域.混合区由于热影响区的存在腐蚀速率最快.保护气中氮气的添加促进了奥氏体的生成，降低了腐蚀电流密度一个数量级，提高了整体的腐蚀性能.

Research on microstructure and corrosion behavior of multi-pass welded joints of hyper duplex stainless steel

Microstructure and corrosion properties of multi-pass welded joints of 2507 hyper duplex stainless steel by multi-pass gas tungsten arc welding were studied. Two different shielding gases were used in the tungsten argon arc welding. The effect of welding pass and nitrogen addition on the microstructure and corrosion performance was discussed. The results showed that the weld center had higher austenite content. Its corrosion rate was about 0.68 times of the weld root. The weld cap showed better corrosive properties due to its obvious intragranular austenite though its austenite content was close to weld root. The weld root was the weakest region in the weld metal. The mixing zone showed the highest corrosion rate due to the existence of heat affected zone. The addition of nitrogen promoted the formation of austenite and reduced the corrosion current density by one magnitude and improved the overall corrosion performance.