309S耐热不锈钢蠕变行为及寿命预测

以工业化生产的309S奥氏体耐热不锈钢为研究对象,在不同温度和应力条件下进行单轴拉伸蠕变实验.结果表明:700℃/100 MPa蠕变断裂时间最长为480.13 h,蠕变曲线有明显的3个阶段;800℃/100 MPa蠕变断裂时间最短为4.61 h,蠕变曲线只有第3阶段,直至断裂.扫描电子显微镜(SEM)观察分析表明,蠕变...

Creep behavior and life prediction of 309S heat-resistant steel

The uniaxial tensile creep experiments of the industrial produced 309S austenitic heat resistant stainless steel were carried out under the different conditions of temperature and stress. The results show that the creep rupture time is 480.13h and the creep curve has all three stages obviously at 700℃/100MPa; the creep rupture time is 4.61h and the creep curve has only the third stage until it breaks at 800℃/100MPa. The creep fracture is transgranular dimple fracture by SEM. The creep behaviour of 309S heat resistant steel followed the power law, the creep stress indices are 9.97 and 6.80 respectively at 700℃ and 800℃. The creep mechanism is Orowan mechanism for dislocation bypassing second phase particle at 700℃. At 800℃, the creep mechanism is mainly controlled by dislocation slip and climb. The apparent activation energy of creep at 50MPa is 41484kJ/mol. The creep life prediction models of 309S heat resistant steel at 700℃ and 800℃ were established based on Larson Miller parameter method and Kachanov Robatnov creep damage method, and the prediction accuracy of Larson Miller parameter method is significantly higher than that of Kachanov Robatnov creep damage life prediction model.