316LN钢高温塑性及其断口特征

Plasticity at elevated temperature and fracture character of 316LN steel

利用Gleeble-1500D热力模拟试验机,对316LN钢进行温度为950~1200℃,应变速率分别为0.005、0.05、0.5和1s-1的热力模拟试验。借助扫描电镜（SEM）对断口进行观察,研究316LN钢的高温塑性及高温断裂机制。结果表明：316LN钢高温断裂为韧性断裂,随着温度和应变速率的增加,韧窝尺寸增大,深度增加,塑性增加。同时,采用回归方法构建了断裂应变、塑性指标（延伸率和断面收缩率）分别与变形条件（温度和应变速率）的关系模型,应用这些模型可以计算一定条件下316LN钢的断裂应变、延伸率和断面收缩率,对制定316LN钢的锻造工艺有一定的指导作用。

Thermal-mechanical simulation tests of 316 LN steel were carried out on Gleeble-1500 D thermal-mechanical simulator with temperature in the range of 950 ~ 1200 ℃ and strain rates of0.005,0.05,0.5and 1s-1.The fractures were observed using a Scanning Electron Microscope（SEM）.The plasticity and fracture mechanism of 316 LN steel at elevated temperature were studied.The results show that the fracture of 316 LN steel at elevated temperature is ductile fracture.The size and depth of dimples increase with the temperature and strain rate.The plasticity also increases with temperature and strain rate. Meanwhile,the relationship models between fracture strain and deformation conditions（temperature and strain rate）and between plastic indexes（elongation and area reduction）and deformation conditions were established using regression method,respectively.Employing these models,the fracture strain,elongation and area reduction of 316 LN steel under certain conditions can be calculated.This study provides reference to the design of forging technology of 316 LN steel.