晶粒分布形态对焊趾短裂纹疲劳行为影响的模拟  

SIMULATION OF EFFECTS OF GRAIN DISTRIBUTION MORPHOLOGY ON FATIGUE BEHAVIOR OF SHORT CRACKS AT WELD TOE

作　　者：胡珂 魏国前[1,2] 闫梦煜 冯梓彬 李阿虎 HU Ke;WEI GuoQian;YAN MengYu;FENG ZiBin;LI AHu(Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering,Wuhan University of Science and Technology,Wuhan 430081,China;Key Laboratory of Metallurgical Equipment and Control Technology,Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,China;Precision Manufacturing Institute,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]武汉科技大学机械传动与制造工程湖北省重点实验室,武汉430081 [2]武汉科技大学冶金装备及其控制教育部重点实验室,武汉430081 [3]武汉科技大学精密制造研究院,武汉430081

出　　处：《机械强度》2023年第1期84-90,共7页Journal of Mechanical Strength

基　　金：国家自然科学基金项目(51575408)资助。

摘　　要：焊接结构的疲劳裂纹常常萌生于焊趾局部。在复杂的冶金物理作用下,焊趾局部的微观晶粒尺寸及其分布形态呈现明显差异性。为了探究晶粒分布形态对焊趾短裂纹疲劳行为的影响,针对十字焊接接头试件,对焊趾局部的不同区域进行了金相检验,获得粗晶区和细晶区的平均晶粒尺寸,构建了虑及晶粒分布形态的二维代表性体积单元(RVE)模型,基于FIP参量和McDowell模型实现了不同晶粒分布形态对焊趾短裂纹的成核与疲劳扩展行为的模拟,结果表明,微观晶粒尺寸和取向是焊趾短裂纹成核行为的重要影响因素;晶粒分布形态对短裂纹的早期行为影响较小,但在裂纹扩展至某个阈值长度之后,影响逐渐显著;一般情况下,细晶到粗晶的过渡方式可降低短裂纹的扩展速率。Fatigue cracks of the welded structure often initiate at the weld toe. Under the complex metallurgical-physical process, the grain sizes and their distribution morphology at the weld toe site show obvious variation. In order to investigate the influence of grain distribution morphology on the fatigue behavior of the weld toe short cracks, metallographic tests were carried out for different areas of the weld toe for the cruciform joint specimen to obtain the average grain sizes of the coarse-grain region and the fine-grain region. Two-dimensional representative volume element(RVE) models considering grain distribution morphology were constructed. Based on FIP parameters and McDowell model, the nucleation and fatigue propagation behavior of the weld toe short cracks with different grain distribution morphology were simulated. The results showed that grain size and orientation are important factors influencing the nucleation behavior of the weld toe short cracks. The grain distribution morphology has little effect on the early behavior of short cracks, but the effect is gradually significant with the cracks propagating to a certain threshold length. In general, the fine-to-coarse grain transition mode can reduce the growth rate of short cracks.

关 键 词：晶粒分布形态 焊趾短裂纹 裂纹成核 裂纹疲劳扩展 RVE模型 

分 类 号：TG405[金属学及工艺—焊接]