耐磨钢NM400冷弯开裂分析

Analysis on cold bending fracture of wear-resistant steel NM400

厚度为20 mm的NM400钢板在冷弯过程中开裂。从冷弯工艺参数、材料拉伸性能、显微组织及夹杂物类型、尺寸分布对NM400钢板开裂原因进行了分析。结果表明:NM400钢板冷弯开裂主要由钢板中微米级TiN夹杂物引起。冷弯变形过程中,夹杂物与基体界面处应力集中,导致微裂纹在界面处形核并扩展,最终导致冷弯断裂。通过降低N含量至4×10^(-5)以下,耐磨钢NM400冷弯过程中无裂纹产生。

Aimed at the cold bending fracture in 20 mm thick NM400 plates,the cold bending process parameters,tensile properties,microstructure,inclusion types and size distribution were investigated to find the cause of fracture.The results show that bending fracture in NM400 plate is mainly caused by micron-size TiN inclusions.During the cold bending deformation,the stress concentration at the interface between inclusion and matrix leads to the nucleation and propagation of microcracks,and eventually leads to cold bending fracture.By reducing N content to below 4×10^(-5),the cracking risk during cold bending process of NM400 steel is disappeared.