氢对TC4钛合金电子束焊接头疲劳断裂特性的影响
Effects of Hydrogen on Fatigue Fracture Characteristics of TC4 Alloy Welded joints by Electron Beam
刘鹏涛1， 赵秀娟1， 刘 昕2， 任瑞铭1
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作者单位：（1. 大连交通大学 材料科学与工程学院，辽宁 大连 116028；2. 北京航空制造工程研究所，北京 100024）
中文关键字： TC4钛合金；氢；疲劳；断口分析
英文关键字：TC4 titanium alloy; hydrogen; fatigue; fractographic analysis
中文摘要：采用统计分析的方法研究了固溶氢对TC4钛合金电子束焊接头疲劳寿命的影响,并对接头试样的疲劳断裂位置和疲劳断口形貌进行了观察与分析。结果表明,氢显著降低了TC4钛合金试样的疲劳寿命,氢含量0.028%(质量分数)的钛合金的疲劳寿命仅为未充氢试样的一半,当氢含量增大到0.120%时,疲劳寿命降到了未充氢的五分之一。疲劳试样多数断于接头的热影响区,造成这一结果的主要原因是热影响区的组织不均匀性和氢含量相对较高。断口的形貌特征表明,氢促进了疲劳裂纹的萌生和增加了裂纹扩展的速度,导致钛合金电子束焊接头的疲劳寿命显著降低。
英文摘要：The effects of hydrogen on the fatigue life of TC4 alloy electron beam welded joints were evaluated by statistic approach. The fatigue fracture positions of joints as well as the fracture surface morphologies of specimens were observed. It was found that the fatigue life is evidently reduced by hydrogen charging. The fatigue life of the joint with 0.028 wt% hydrogen is half of the hydrogen-free joint. When hydrogen content is 0.120 wt%, the fatigue life of hydrogen-charged joint decreases to one fifth of the hydrogen-free joint. The fracture occurres at heat affected zone (HAZ) of most fatigue specimens. This is due to the structure inhomogeneity and the higher hydrogen content of materials at HAZ. The fractographic observation results indicate that the hydrogen can accelerate the fatigue crack initiation and increase the speed of crack propagation, which leads to the obvious decrease of fatigues life of TC4 alloy joints welded by electron beam welding.