【摘要】 采用应变控制方法,测试了TC4钛合金电子束焊接接头及母材低周疲劳性能,记录并比较了不同位置处的载荷-应变曲线,利用扫描电镜观察分析了低周疲劳断裂方式及断口形貌。研究结果表明:在高应变条件下,由于焊接接头区塑性变形能力较差,其低周疲劳寿命低于母材,低应变条件下,母材与焊接接头低周疲劳寿命相当;低周疲劳试样最终失效断裂均发生在母材区,但焊接接头区也存在明显表面裂纹,这与焊接接头区具有较高的强度、抗塑性变形能力及抗疲劳裂纹扩展能力有关。更多还原

【Abstract】 Low cycle fatigue(LCF) properties of electron beam welded(EBW) TC4 alloy were tested and compared with base material(BM) under strain controlled condition.The LCF life of welded joint is obviously lower than that of BM under high Δεt/2 condition,while equal under low Δεt/2 condition,which was explained by the stress-strain loop and plastic feature of microstructure.The failure fracture occured in BM region,which was attributed to the relatively lower strength and weaker resistance to plastic diformation of BM region compared to the welded joint region.However,near surface crack initiated at the welded joint without further propagating due to high resistance to fatigue crack propagating from coarse β grain microstructure.更多还原