P92钢625℃持久性能分段特征与各段中M_(23)C_6及Laves相相参数的定量变化研究

STUDY ON THE MULTI-SEGMENT FEATURE OF 625℃CREEP-RUPTURE PROPERTY AND THE QUATITATIVE CHANGE OF PHASE PARAMETERS OF M_(23)C_6 AND LAVES PHASES IN EACH SEGMENT OF P92 STEEL

研究了P92钢在625℃下加载应力与断裂时间关系曲线的分段特征以及各试样中M_(23)C_6及Laves相参数的定量变化.结果表明,根据该钢在625℃,110—180 MPa条件下的持久实验得到的应力-断裂时间关系曲线的变化趋势,可将该曲线分为高应力-短时段(180—150 MPa,30—454 h)和低应力-长时段(140—110MPa,2881—10122 h)两个特征段;在高应力-短时段,M_(23)C_6相颗粒聚集与粗化占主导;在低应力-长时段,Laves相及M_(23)C_6相颗粒并行聚集与粗化;相成分、相含量及相间元素分配量(相参数)随时间及应力而变化.

In the present study,the multi-segment feature of stress vs rupture-time plot and the corresponding quatitative change of phase parameters of M23C6 and Laves in each segment were investigated for P92 steel samples subjected to 625℃creep-rupture tests.The results indicate that the stress vs rupture-time plot obtained from the test results can be divided into two segments（higher stress level and shorter rupture time segment：180-150 MPa/30-454 h,and lower stress level and longer rupture time segment：140-110 MPa/2881-10122 h） respectively,and the microstructural evolution is closely related to the feature of each segment.In the higher stress level and shorter rupture time segment the M23C6 particles are coarsened,while in the lower stress level and longer rupture time segment both M23C6 and Laves phases are coarsened,but the latter is predominantly.The average composition, the amount and the elemental partitioning of each alloy phase called phase parameters can be determined by a multiphase separation method developed.