TC21钛合金电子束焊接接头超高周疲劳行为研究

发布时间：2018-03-25 17:05

本文选题：TC钛合金　切入点：电子束焊接接头　出处：《机械工程学报》2015年12期

【摘要】：采用超声疲劳试验方法(20 k Hz),研究TC21钛合金电子束焊接接头的超高周疲劳性能与断裂机理。结果表明,TC21钛合金电子束焊接接头的疲劳性能要远低于母材的疲劳性能。在短寿命阶段,电子束焊接接头和母材的疲劳裂纹均在表面萌生;当寿命增大时,两者疲劳裂纹的萌生位置均由表面转向内部,母材的疲劳裂纹主要萌生于内部显微组织,而电子束焊接接头疲劳裂纹主要萌生于内部焊接气孔缺陷。当寿命较长时,疲劳源区会出现"鱼眼"形貌特征,源区附近有白色颗粒状细晶区,即细晶区(Fine granular area,FGA),其应力强度因子在2.90~3.33 MPa·m1/2,与疲劳寿命没有直接关系,可以认为是疲劳裂纹扩展门槛值。此外,基于AKINIWA小裂纹扩展理论,定量分析气孔尺寸与TC21焊接接头疲劳极限、疲劳应力的关系。
[Abstract]:The ultra-high cycle fatigue properties and fracture mechanism of TC21 titanium alloy electron beam welded joints were studied by ultrasonic fatigue test method. The results show that the fatigue properties of electron beam welded joints of TC21 titanium alloy are much lower than those of base metal. At short life stages, The fatigue cracks of electron beam welded joints and parent metal both germinated on the surface, and when the life increased, the locations of fatigue cracks both changed from the surface to the interior, and the fatigue cracks of the base metal mainly originated from the internal microstructure. The fatigue crack of the electron beam welded joint mainly originates from the internal weld pore defect. When the life is longer, the "fish-hole" appearance will appear in the fatigue source region, and there are white granular fine crystal areas near the source region. The stress intensity factor is 2.90 ~ 3.33 MPa / m ~ (-1 / 2), which has no direct relation with fatigue life and can be considered as the fatigue crack growth threshold. In addition, based on the AKINIWA small crack growth theory, the pore size and fatigue limit of TC21 welded joints are quantitatively analyzed. The relationship between fatigue stress and fatigue stress.
【作者单位】：北京航空航天大学材料科学与工程学院;
【基金】：国家自然科学基金资助项目(51101009)
【分类号】：TG405;TG456.3

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