汽轮机转子30Cr1Mo1V钢长期服役状态下的高温疲劳行为

Fatigue Behavior of 30Cr1Mo1V Rotor Steel at Elevated Temperature After Long-term Service

研究了已服役16年的汽轮机30Cr1Mo1V高中压转子钢的高温疲劳性能。选取高应力段、高温段和中压段等3个典型部位切向样品进行538℃条件下的低周疲劳性能和疲劳裂纹扩展速率性能比较试验,试验结果表明,高温段的疲劳性能劣化最严重,高应力段次之。相应的微观结构观察发现,30Cr1Mo1V转子钢原始的回火索氏体组织发生了明显的分解,这一现象在高温和高应力段材料中表现更为明显,碳化物粗化或球化严重,晶界碳化物呈连续链状分布,在高温段的晶界处还发现了少量的蠕变孔洞,这些微观结构现象应是材料性能退化的原因。

The low cycle fatigue and fatigue crack growth rate tests are described in the detail for a steam turbine rotor steel 30Cr1Mo1V which had been in service for 16 years.Three typical sections of the examined rotor,i.e.high-temperature,high-stress and medium-stress,were experimented at 538℃.The test results shows that the property of the high temperature section is degraded most severely and the high stress section takes the second place.The corresponding microstructure observations show that the original sorbite structure decomposed almost completely in high temperature and high stress sections.Carbides were coarsened or spheroidized strikingly,with a continuous chain of large size carbides present in the grain boundary.A few microvoids were found at grain boundary in the high temperature section.These phenomena in microstructure might be the reasons for properties degradation.