Ti_3Al合金激光焊接接头高温拉伸性能及显微组织  

Microstructure and high-temperature tensile properties of Ti_3Al alloys laser welding joint

作　　者：王国庆[1] 赵玥[1] 吴爱萍[1] 邹贵生[1] 任家烈[1] 

机构地区：[1]清华大学机械工程系教育部先进成形制造重点实验室,北京100084

出　　处：《中国有色金属学报》2007年第11期1803-1807,共5页The Chinese Journal of Nonferrous Metals

摘　　要：研究Ti-24Al-17Nb合金激光焊接接头的室温及高温拉伸性能,并分析接头显微组织和拉伸断口。研究结果表明,室温下焊缝为单一β/B2相柱状晶组织,室温横向拉伸时接头强度与母材强度相当、塑性有所下降、但仍有25%左右的伸长率,断裂大部分发生在母材部位、少部分断裂在焊缝;高温拉伸时断裂均发生在焊缝部位。高温拉伸时,接头组织发生变化,α2相和B2相向O相转变;焊缝β/B2相向O相转变的切变相变,使原来柱状晶晶界应变集中、容易产生微裂纹,使接头高温强度和塑性明显降低,高温拉伸断口呈现沿晶断裂和解理断裂的脆性断裂形式。The high-temperature and room-temperature tensile properties of Ti-24Al-17Nb （mole fraction, %） alloys laser welding joints were investigated, and the microstructure and fracture of the joints were studied. The results indicate that the microstructures of the welds are consisted of β/B2 with columnar crystals, the strength of the joints tensioned transversely at room-temperature is almost same as that of the base metal, and the ductility reaches 25%. Cracks occur in the base metal. During the high-temperature tension the cracks occur in the welds. After high-temperature tension, some of the phase a2and phase B2 of the base metal and HAZ in joints turn to phase O, and phase B2ofthe welds turn to phase O. The phase changes bring about strain concentration, and induce fracture. The strength and ductility of the joints at high temperature descend significantly. The fracture types of high-temperature tension joints are intergranular fracture and cleavage fracture.

关 键 词：TI3AL合金 激光焊接 高温拉伸性能 显微组织 

分 类 号：TG406[金属学及工艺—焊接]