应力三轴度对316LN钢临界损伤值的影响

Influence of stress triaxiality on critical damage value of 316LN steel

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。

The tensile experiments were carried out on Gleeble-1500D thermo-simulator for 316LN steel with the temperature of 1050 ℃ and strain rate of 0.5s-1 .The notched radii of the specimens with the dimensions of Φ10mm × 121.5mm were 0.5mm , 1mm ,2mm and 4mm .The true stress-true strain curves of different notched radii specimens were obtained .The maximum val-ues of stress triaxiality when the specimens started to be tensioned and the critical damage values when the voids nucleated were obtained by the numerical simulation . The results show that the critical damage values of the notched specimens increase with the stress triaxiality increasing , that is , the larger the stress triaxiality , the less easily the cracks occur . The quantitative relation-ships between the stress triaxiality and the void nucleation strain were established by the regression analysis of the experimental data and the simulated results .