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利用Gleeble-1500D热模拟机对316LN钢做温度1 050℃、应变速率0.5s-1的高温拉伸试验,试样尺寸Φ10mm×121.5mm,缺口半径分别为0.5mm、1mm、2mm和4mm,得到不同缺口半径试样的真应力-真应变曲线。通过数值模拟得到试样初始拉伸时的应力三轴度最大值及空洞形核时的临界损伤值,结果表明,缺口试样的临界损伤值随应力三轴度的增大而增大,即应力三轴度越大,裂纹越不容易萌生。通过对实验数据和模拟结果的回归分析,建立应力三轴度与空洞形核应变的定量关系模型。
Using the Gleeble-1500D thermal simulator, the high-temperature tensile test of 316LN steel at temperature of 1 050 ℃ and strain rate of 0.5s-1 was performed. The sample size was Φ10mm × 121.5mm and the notch radius was 0.5mm, 1mm, 2mm and 4mm respectively. True Stress - True Strain Curves of Different Notch Radius Specimens. By numerical simulation, the maximum value of stress triaxiality and the critical damage value at cavity nucleation are obtained. The results show that the critical damage value of notch specimen increases with the increase of stress triaxiality, that is, The greater the stress triaxiality, the less crack initiation is easy. Through the regression analysis of experimental data and simulation results, a quantitative relationship model between stress triaxiality and cavity nucleation strain is established.