【摘要】 利用Gleeble-3500型热模拟试验机对不同缺口半径(0.5,1.0,2.0,4.0 mm)的铸态42CrMo钢缺口试样进行不同温度(1 223,1 273,1 373 K)下的热拉伸试验,基于应力三轴度分析了其高温拉伸断裂行为。结果表明:较高拉伸温度下缺口试样的流变应力较小;随着缺口半径减小,缺口试样流变应力和峰值应力增加,断裂应变减小;当缺口半径为0.5,1.0 mm时,应力三轴度最大值向最小横截面圆心转移;当缺口半径为2.0,4.0 mm时,拉伸过程中最小横截面圆心处的应力三轴度始终最大;随着缺口半径增加,应力三轴度减小;温度由1 223 K升至1 373 K,试样断口组织平均晶粒尺寸增大;缺口半径由0.5 mm增加至4.0 mm,平均晶粒尺寸增大,微空洞且尺寸及面积分数增加。更多还原

【Abstract】 The as-cast 42CrMo steel notch samples with different notch radiuses(0.5, 1.0, 2.0, 4.0 mm) were subjected to thermal tensile tests at different temperatures(1 223,1 273,1 373 K) with Gleeble-3500 thermal simulator. The tensile fracture behavior at high temperature was analyzed based on stress triaxiality. The results show that the flow stress of the notched sample at relatively high temperature was relatively small. With the decrease of notch radiuses, the flow stress and peak stress increased, and the fracture strain decreased. When notch radiuses were 0.5 and 1.0 mm, the maximum stress triaxial degree shifted to the center of the minimum cross section. When notch radiuses were 2.0 and 4.0 mm, it was always located in the stress triaxial at the center of the minimum cross section during tension was the largest. With the increase of notch radiuses, the stress triaxial value decreased. The average grain size of the fracture structure of the sample increased from 1 223 K to 1 373 K. When notch radiuses increased from 0.5 mm to 4.0 mm, the average grain size increased, microvoidage appeared and the size and area fraction increased.更多还原