电子束焊接Ti-6Al-4V合金接头的疲劳裂纹尖端微区形态

中国有色金属学报, 2011, 21(1): 102-109.

电子束焊接Ti-6Al-4V合金接头的疲劳裂纹尖端微区形态

籍龙波 ^1, , 胡树兵 ^2, , 李行志 ^3, , 陈冀彦 ^4, , 肖建中 ^5,

1.华中科技大学,材料成形与模具技术国家重点实验室,武汉430074

2.华中科技大学,材料成形与模具技术国家重点实验室,武汉430074

3.华中科技大学,材料成形与模具技术国家重点实验室,武汉430074

4.华中科技大学,材料成形与模具技术国家重点实验室,武汉430074

5.华中科技大学,材料成形与模具技术国家重点实验室,武汉430074

基金项目: 华中科技大学材料成形与模具技术国家重点实验室自主课题(09-10) 国家磁约束核聚变能研究专项基金资助项目(2010GB109000)

关键词： Ti-6Al-4V合金 , 电子束焊接 , 疲劳 , 裂纹尖端 , 显微形态

Morphologies at fatigue crack tip of Ti-6Al-4V electron beam welding joints

通过对Ti-6Al-4V合金板材预制一定深度的疲劳裂纹,研究母材与焊缝区疲劳裂纹尖端的TEM显微形态.结果表明:经历疲劳循环后,位错密度大大增加,α/β相界面位错密度高,易成为位错形核的源区;在周期性疲劳载荷的作用下,位错以源区为原点呈放射状向四周发散运动;在焊缝区马氏体板条之间的细碎相之间,位错聚集严重,说明细碎相也易成为位错萌生的源区,从而成为疲劳裂纹形核的源区;在焊缝区马氏体板条宽度越窄,位错聚集密度越高,易成为疲劳裂纹萌生的位置.此外,TEM观察证实了裂纹尖端存在一定尺寸的塑性变形区.通过焊接接头分区的TEM对比分析,获得焊缝区比母材区更易萌生疲劳裂纹的相关证据.

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