钛合金焊接接头超长寿命疲劳特性研究  

Study on ultra-long-life fatigue properties of welded joints under high-frequency loading

作　　者：何超[1] 田仁慧[1] 王清远[1] 

机构地区：[1]四川大学建筑与环境学院,四川成都610065

出　　处：《中国测试》2012年第3期20-22,26,共4页China Measurement & Test

基　　金：国家自然科学基金项目(10925211)

摘　　要：本文针对TC4钛合金焊接接头试件进行了超声疲劳实验,研究其在高频低幅载荷作用下的超高周疲劳行为,整个实验在室温条件下进行,应力比R=-1。通过实验得到了TC4焊接接头试件在107～109周次范围内的疲劳寿命S-N曲线,发现其呈连续下降趋势,当循环周次超过107周次以后,材料仍然会发生疲劳破坏,断面出现在焊接缝中央或热影响区,呈现脆性断裂的形式,不存在传统意义上的疲劳极限。对比TC4母材实验数据发现,在相同疲劳寿命的条件下,焊接接头试件疲劳强度相比母材下降了70%左右。试件断口表面的SEM电镜扫描分析结果显示疲劳裂纹均起源于焊接过程引起的气孔、夹杂等缺限处。In order to investigate the ultra-long-life fatigue properties of TC4 welded joints, ultrasonic fatigue tests of base metal and welded joints were carried out for TC4 mainly used in aerospace. The experiment was conducted in ambient air at room temperature with a stress ratio R=-1. The S-N fatigue curves were obtained in the range of 107-109 cycles of base metal and welded joints for TC4, and experimental results indicate the characteristic of continually decreasing type. The fatigue failure still occurred after 107 cycles of loading, and the fatigue limit in traditional does not exist in this case. The fatigue strength of welded joints specimens descend about 70% compared to base metal when both specimens have the same fatigue lives. The observation of fractography of fatigue failure by scanning electron microscopy shows that all fatigue cracks initiate from the surface defects of the specimen.

关 键 词：超声疲劳实验 TC4 焊接接头 S-N曲线 断口分析 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG407[金属学及工艺—金属材料]