电厂过热器用12Cr2MoWVTiB钢管使用温度上限的探讨

Discussion on Upper Temperature Limit of 12Cr2MoWVTiB Steel Tube in Superheater for Power Plant

以某电厂在当量温度585℃运行约14万h的过热器受热面12Cr2MoWVTiB钢管作为研究对象,研究了其宏观形貌、化学成分、显微组织及室温和高温力学性能,对其使用温度上限进行了探讨。结果表明:该钢管未出现明显的胀粗和减薄现象,组织中未见蠕变孔洞,组织老化级别为3级,室温力学性能比未服役的略有下降,仍满足标准要求;该钢管在运行约14万h后仍具有良好的抗高温蠕变性能,其持久强度仅比标准指标低12.1 MPa;结合该电厂过热器受热面管的运行情况认为,12Cr2MoWVTiB钢受热面管可以在585℃下安全运行,这与DL/T 715-2015规定的575℃使用温度上限有所冲突。

A superheater in power plant was operated at equivalent temperature of 585℃for 140 000h;Macromorphology,chemical composition,microstructure and mechanical properties at room temperature and elevated temperature of the heat surface tube of 12Cr2MoWVTiB steel from the superheater were studied,and upper temperature limit of the steel tube was discussed.The results show that no obvious swelling and thinning were observed in the steel tube.No creep holes were found in the microstructure and the aging grade of microstructure was grade 3.The mechanical properties at room temperature were slightly lower than those of unoperated steel tube,and still met the standard requirements.After service for about 140 000h,the steel tube still had good hightemperature creep resistance;the stress-rupture strength was only 12.1MPa lower than the standard requirement.Considering the running situation of heat surface tube in superheator of the power plant,it was suggested that 12Cr2MoWVTiB steel heat surface tube can be reliably operated at temperatures no higher than 585℃;this conflicts with the 575℃upper temperature limit specified in DL/T 715-2015.