双相钛合金Ti-6Al-4V微观缺陷疲劳演化的片层结构分布效应  

Effect of Lamellar Structure Distribution on Micro-Defect Evolution in Dual-Phase Ti-6Al-4V Alloy under Fatigue

作　　者：陈坤荣 汤可可[1] 杜兆钧 CHEN Kunrong;TANG Keke;DU Zhaojun(School of Aerospace Engineering and Applied Mechanics,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学航空航天与力学学院,上海200092

出　　处：《力学季刊》2021年第4期665-673,共9页Chinese Quarterly of Mechanics

基　　金：国家自然科学基金(11872278);上海市自然科学基金(21ZR1467200)。

摘　　要：本文研究疲劳载荷作用下双相钛合金Ti-6Al-4V中片层结构对微观几何缺陷区域演化的影响.基于晶体塑性有限元(Crystal Plasticity Finite Element, CPFE)理论,建立含微观椭圆缺陷的双相片层代表性体积单元(Representative Volume Element, RVE)模型,通过调控缺陷附近的微观组织形貌,使缺陷两端分别出现单相结构和片层结构,以突出双态合金中片层结构分布对微观缺陷演化的影响.模拟结果表明,位于微观缺陷两侧的晶粒,片层结构的应变敏感性更大,应变沿缺口环向和沿晶内均呈不连贯波动.片层结构通过调节晶内应变,扩大承载范围,可提高双相钛合金的抗疲劳特性.这一研究结果可为双相钛合金的疲劳裂纹萌生提供一个新的解释途径.The purpose of this paper is to study the effect of lamellar structure in dual-phase titanium alloys Ti-6 Al-4 V on microdefect-induced fatigue cracking. Based on Crystal Plasticity Finite Element(CPFE) theory, the dual-phase Representative Volume Element(RVE) models consisting of elliptical notches are formulated for Ti-6 Al-4 V alloys. Through varying the microstructure morphology around the elliptical notch, single-phase structure or the lamellar structure emerges at both ends of micro-defect, such that the influence of the lamellar structure distribution on fatigue cracking is highlighted. The numerical results show that, strain sensitivity is significant in the vicinity of lamellar structure located on the both sides of micro-defect. Strain distribution within single grain along the circumferential direction is prone to be discontinuous, which means fatigue resistance of Ti-6 Al-4 V alloys can be improved by adjusting strain within the grains through expanding load-bearing area. The results provide new insight into the fatigue crack nucleation in dual-phase titanium alloys.

关 键 词：双相钛合金 片层结构 微观缺陷 晶体塑性有限元 疲劳裂纹 

分 类 号：O344.3[理学—固体力学]