热轧钢延性损伤断裂过程各向异性的细观力学分析

Meso-mechanical analysis of fracture process of anisotropic ductile damage in hot-rolled steel

对热轧钢中的长条形初始损伤孔洞承受不同方向最大正应力时的后续损伤演化和断裂的过程进行细观有限元分析.结果表明:热轧钢中的长条形夹杂物与基体剥离后形成的长条形孔洞在后续加载中,其周围产生的局部高应力应变集中及其相互作用使孔洞长大.孔洞长大行为存在明显的个体差异,个别大孔洞的快速长大和聚合对材料破坏起主导作用.当长条形孔洞承受不同方向的最大正应力加载时,孔洞周围产生的局部应力应变分布及其相互作用不同,孔洞长大速率及其聚合时的临界外加主应变不同,相应的材料延性起裂韧性不同.当最大正应力与孔洞长条平行时,韧性最高;垂直时,韧性最低.

Meso-mechanical analysis has been conducted with finite element for a hot-rolled steel of 16MnR to investigate the effect of the elongated pre-damage voids on the subsequent damage evolution and fracture process under multidirectional maximum normal stresses. The analysis results showed that, when the elongated voids due to the decohesion of the inclusions from base material were loaded subsequently, the local high stress and strain concentration around the voids and their interactions promoted the growth of voids. There was distinctly different behavior of voids＂ growth among these voids. The rapid growth and coalescence of a few big voids predominated the fracture process of the material. When the elongated voids were subjected to the load caused by multidirectional maximum normal stress, the distribution of local high stress and strain around the voids and their interactions were different, causing different growth rates of voids and the critically applied normal strain of coalescence, so that the corresponding ductile fracture initiation toughness was also different. If the maximum normal stress was parallel to the elongated voids, the toughness would be the highest; when perpendicular to them, the toughness-the lowest.