TC4钛合金薄板激光焊接头疲劳性能研究

研究了TC4钛合金薄板母材及其激光焊接头的拉伸和疲劳性能.结果表明:与母材相比激光焊接头的强度升高,延伸率下降;拉伸试样均断在母材.激光焊接头的疲劳寿命在低应力水平时高于母材,而在高应力水平时低于母材.在疲劳扩展区,母材为韧性穿晶断裂,熔合区则呈现出韧性和脆性相混合的断裂形貌;在瞬断区,母材由等轴韧窝组成,而熔合区主要为粗大的穿晶解理平面.

Study on Fatigue Property of Laser Welded Joints of TC4 Titanium Alloy Sheet

The tensile and fatigue properties of TC4 titanium alloy sheet and its laser welded joints were investigated. The results showed that the strength of laser welded joints was increased and the elongation rate was decreased compared with base metal. The tensile fracture of laser welded joints was found on base metal. The fatigue life of laser welded joints was higher than that of base metal under low stress levels, nevertheless, the fatigue life of laser welded joints was lower than that of base metal under high stress levels. In fatigue crack expansion zone, base metal was tough transgranular fracture, however, a mixed fracture characteristics of tough and brittle was noted on fractographs of fusion zone. In transient crack zone, the SEM fractographs of base metal consisted of equal-axis ductile voids, the fusion zone was mainly consisted of course transgranular cleavage facets.