长期运行后汽轮机转子裂纹扩展行为的研究

An Investigation on Crack Growth Behavior of a Turbine Rotor After Long-period Operation

对运行16年的30Cr1Mo1V亚临界汽轮机高中压转子进行解剖试验,采用直流电位法对材料在538℃下的蠕变裂纹、蠕变-疲劳裂纹萌生与扩展行为进行了研究,分析了不同初始应力强度因子对蠕变裂纹扩展孕育时间和蠕变裂纹扩展速率的影响,并对高温段和低温段的相关性能进行了比较,研究了不同保持时间对蠕变-疲劳裂纹扩展行为的影响,同时还分析了不同条件下裂纹扩展行为的时间或循环相关性.结果表明:疲劳缩短了蠕变-疲劳裂纹的扩展孕育期,加速了裂纹的扩展;载荷保持时间较短情况下,蠕变-疲劳裂纹扩展行为与循环相关;载荷保持时间较长情况下,裂纹扩展行为与时间相关.

Dissection tests were carried out on a HP-IP 30CrlMolV steel rotor for the subcritical pressure turbine, which had been operated for about 16 years, during which the initiation and propagation of the creep and creep-fatigue cracks were studied at 538℃ using D. C. electrical potential technique, so as to analyze the influence of initial stress intensity factor on initiation time and propagation rate of the creep cracks, while a comparison made on the crack property of specimens respectively taken at high and low temperature sections. The effect of hold time on growth behavior of creep-fatigue cracks was also investigated, and the correlations between crack growth and time or cycle was simultaneously analyzed under different conditions. Results show that for creep-fatigue cracks, the initiation time may be reduced and the propagation rate may be raised by the effect of fatigue; the growth behavior of creep-fatigue cracks is cycle- dependent at short hold time, which becomes time-dependent at long hold time