载荷方向和焊缝余高对氩弧焊缝疲劳性能的影响

采用疲劳寿命测试和观测断口方法,研究焊接方向和焊缝余高对TC2钛合金氩弧焊缝疲劳性能的影响。结果表明:同种焊接方向,保留焊高试件的疲劳寿命低于去焊高试件;同种焊缝余高处理方式,斜焊试件的疲劳寿命高于直焊试件。去焊高试件于气孔缺陷处萌生裂纹,保留焊高试件疲劳裂纹起源于焊趾。裂纹扩展初期,裂纹均在焊缝内扩展,有明显的疲劳条带;扩展后期,斜焊试件裂纹穿过焊缝进入母材,存在典型的韧性疲劳条带。直焊试件疲劳瞬断区韧窝少而浅;斜焊试件在母材瞬断,韧窝多且密。

Influence of Loading Direction and Weld Reinforcement on Fatigue Performance of TIG Weld Seam

The influence of loading direction and weld reinforcement on fatigue performance of TC 2 ti-tanium alloy TIG weld seam was investigated via fatigue experiments and SEM fracture observation . The results show that the fatigue life of retaining weld reinforcement specimens is lower than that of removing one in the same weld direction .The fatigue life of oblique weld specimens is higher than that of straight one with the same weld reinforcement treatment .The initiation of removing weld rein-forcement specimens' fatigue crack sources is in the hole defect ,but the weld reinforcement specimen initiate at the weld toes .During the early stage of fatigue crack propagation ,the cracks all grow inside the weld seam metal with obvious fatigue striation .And the fatigue cracks of oblique weld specimens pass through the weld seam into the base with a typical toughness fatigue striation during the last stage of fatigue crack propagation .The dimple of straight weld specimens is little and shallow in the final fracture zone .The oblique weld specimens broke in the base metal area ,and the dimple is dense.