TC17钛合金电子束焊接接头的疲劳裂纹扩展规律及疲劳剩余寿命

Fatigue Crack Growth Properties and Fatigue Crack Growth Life of the EB-joints of TC17 Titanium Alloy

首先通过试验取得母材及焊接接头的疲劳裂纹扩展速率,然后结合TC17钛合金电子束焊接接头CTOD试验结果及裂纹容限计算值,以估算其疲劳剩余寿命。结果表明:在低应力水平或低△K下,TC17电子束焊缝的da/dN数据与母材的基本相当;然而随着应力水平的增加,焊缝的da/dN值越来越大。在初始裂纹尺寸相同的情况下,TC17合金电子束焊缝与母材疲劳裂纹扩展寿命曲线存在交叉点。当应力幅大于交叉点应力幅时,TC17母材疲劳裂纹扩展到临界裂纹尺寸的剩余寿命要高于相应焊缝的剩余寿命;当应力幅小于交叉点应力幅时,TC17母材扩展到临界裂纹尺寸的剩余寿命要低于相应焊缝的剩余寿命。

To study the fatigue properties of TC17 titanium EB-joint, this paper first tested the fatigue crack growth rate of the base metal and welded joints, and then combine it with TC17 titanium EB-joints＇ CTOD test results and crack tolerance calculated value to estimate its value. The results show that under the low stress level or under the low △K value, da/dN value of TC 17 EB-joint and base metal is almost equal, but when the stress level increases, the joint＇s da/dN value is increased. When the initial crack size is equal, the fatigue crack growth curve of EB-joint intercross the life curve of base metal, and then, when the stress range is greater than the value at the intersection of stress, the fatigue crack growth life of base metal at fatigue crack growing to the critical crack size is higher than the life of the EB-joint; when the stress range is less than the value at the intersection of stress, the fatigue crack growth life of base metal at fatigue crack growing to the critical crack size is lower than the life of the EB-joint.