發(fā)布時間：2018-03-25 17:05

  本文選題：TC鈦合金　切入點：電子束焊接接頭　出處：《機械工程學(xué)報》2015年12期

【摘要】：采用超聲疲勞試驗方法(20 k Hz),研究TC21鈦合金電子束焊接接頭的超高周疲勞性能與斷裂機理。結(jié)果表明,TC21鈦合金電子束焊接接頭的疲勞性能要遠(yuǎn)低于母材的疲勞性能。在短壽命階段,電子束焊接接頭和母材的疲勞裂紋均在表面萌生;當(dāng)壽命增大時,兩者疲勞裂紋的萌生位置均由表面轉(zhuǎn)向內(nèi)部,母材的疲勞裂紋主要萌生于內(nèi)部顯微組織,而電子束焊接接頭疲勞裂紋主要萌生于內(nèi)部焊接氣孔缺陷。當(dāng)壽命較長時,疲勞源區(qū)會出現(xiàn)"魚眼"形貌特征,源區(qū)附近有白色顆粒狀細(xì)晶區(qū),即細(xì)晶區(qū)(Fine granular area,FGA),其應(yīng)力強度因子在2.90~3.33 MPa·m1/2,與疲勞壽命沒有直接關(guān)系,可以認(rèn)為是疲勞裂紋擴展門檻值。此外,基于AKINIWA小裂紋擴展理論,定量分析氣孔尺寸與TC21焊接接頭疲勞極限、疲勞應(yīng)力的關(guān)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.
【作者單位】： 北京航空航天大學(xué)材料科學(xué)與工程學(xué)院;
【基金】：國家自然科學(xué)基金資助項目(51101009)
【分類號】：TG405;TG456.3

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