2205双相不锈钢MIG焊接研究

Metal inert gas welding of alloy 2205 duplex stainless steel

本论文研究了２２０５双相不锈钢ＭＩＧ焊时，热输入量对金相组织，焊缝铁素体含量，硬度及冲击韧性的影响。同时亦研究了混合保护气体（Ａｒ－３０％Ｈｅ－１％Ｏ＿２）对焊缝成形及性能的影响。本论文还提出了采用计算机图象分析进行铁素体含量测定的方法。研究结果表明２２０５双用不锈用具有良好的可焊性，采用ＭＩＧ焊，在不同的规范下均可以获得性能优异的焊缝。在高热输入量时，冲击韧性值仅在－１００℃才有明显的下降。混合保护气体较纯氩保护时可以获得更大的熔深和更好的焊缝形状。计算机图象分析可以更迅速，更精确地测定铁素体含量，且重复性好。

The influence of MIG welding heat input on the microstructure, expecially ferite con-tent, and hardness of 2205 duplex stainless steel plate weldments was investigated for single and multipass bead-on -plate and cruciform fillet weld joints and multipass butt welds.Charpy impact values from 0 to -100℃ Were also measured on the butt welds. For the fil-let welds, pure argon was compared with argon-30% helium-1% oxygen as a shielding gas,from the viewpoint of weld metal penetration and bead shape.Ferrite contents were determinedby computerised image analysis and were compared, for the parent plate omly,withindependent measurements made using the method of point count metallography.The resultsshown that 2205 duplex plate can be MIG welded to give weldments which have excellenttoughness, with satisfactory hardness and microstructures. The highest heat input made the Charrpy values decrease remarkably only at -100℃.The mixed shielding gas gave deeper penetration and better bead profile than the pure argon. Computerised image analysis gavefast, accurate and reproducible ferrite content determination.