基于应力松弛实验对服役25Cr35Ni型耐热钢的高温性能评估

以服役的25Cr35Ni型钢为对象,研究利用应力松弛实验开展高温性能评估的方法以及对持久性能的预测效果。结果表明:由于高温服役后晶界处碳化物出现网链状和奥氏体基体内二次碳化物明显粗化,25Cr35Ni型耐热钢持久性能降低。通过得到的不同温度和应力的松弛蠕变速率曲线及外推关系,结合松弛蠕变速率-断裂时间关系方程,可以实现由松弛实验及少量蠕变持久实验开展持久寿命评估。与基于高温持久实验的预测结果比较,两者吻合较好。

High Temperature Performance Evaluation of As-serviced 25Cr35Ni Type Heat-resistant Steel Based on Stress Relaxation Tests

Based on an as-serviced 25Cr35Ni type steel,the high temperature property evaluation using stress relaxation test(SRT) method and residual life prediction were studied.The results show that creep rupture property decreases because of the formation of network carbides along grain boundaries and coarsening of secondary carbides in the austenitic matrix.Based on the relationship of stress relaxation strain rate curves obtained at different temperatures,and the extrapolation equation of stress relaxation rate-rupture time,it is capable to perform residual life evaluation by combining SRT data and a small amount of creep rupture test(CRT).Good agreement is observed for predicting results performed by current method and traditional method.