Ti-6Al-4V钛合金超音频脉冲TIG焊

Ultra-sonic pulse tungsten inert-gas arc welding of Ti-6Al-4V alloy

进行了Ti-6Al-4V钛合金超音频脉冲氩弧焊(U-TIG)与传统TIG焊,利用X射线探伤检测接头质量,金相显微镜和SEM观察接头组织和断口,利用万能试验机测试接头拉伸性能.结果表明,U-TIG焊能减少焊缝气孔;随着加入脉冲频率的增加,U-TIG焊焊缝组织细化、等轴化,当脉冲频率为45kHz时,晶粒细化效果最好;随着脉冲频率的提高,接头抗拉强度、屈服强度和断后伸长率均有所提高;常规TIG与U-TIG焊接头断口均为准解理断裂机制,但U-TIG断口枝晶破坏痕迹已不明显.

Ti-6Al-4V alloy was welded by conventional tungsten inert-gas arc welding (TIG) and ultra-sonic pulse TIG welding (U-TIG) respectively.The microstructure of the joint was analyzed by means of optical microscope,scanning electron microscope and X-ray diffraction to study the relationship between the macro-properties and the microstructure of the joint.The results show that U-TIG welding can reduce pores of joint.With the increment of pulse frequency,the microstructure becomes finer and finer and is inclined to equiaxed crystal; while pulse frequency is 45 kHz,the effect of grain refinement is the best.Moreover,the properties of joint by U-TIG welding are improved compared with that of conventional TIG.The tensile fractures of the joints welded by TIG and U-TIG all present the character of quai-cleavage crack,but the cellular dendrite depredation is not observed obviously in U-TIG joint.