长时运行高温过热器12Cr1MoV钢寿命评估

以长时运行高温过热器12Cr1MoV钢为研究对象,采用金相检验、扫描电镜、硬度和拉伸性能测试等手段对其组织形貌、化学成分和力学性能进行分析。结果表明,长期高温服役的取样管珠光体球化达到4.5级,碳化物呈链状聚集分布,存在蠕变孔洞和沿晶裂纹,微观组织劣化严重。微观组织劣化越严重,硬度越低,抗拉强度越低,综合力学性能越差。内壁氧化层厚度与微观组织劣化程度无关。运行过程中取样管的当量温度已接近该材质规定的上限温度,取样管剩余蠕变寿命均大于40 000 h。

Life assessment of 12 Cr1 MoV steel for high temperature superheater after long-term service

Microstructure, chemical composition and mechanical properties of the 12Cr1MoV steel sampled from the high temperature superheater after long-term service were analyzed by means of metallographic observation, scanning electron microscope, hardness and tensile property tests. The results show that after long-term service at high temperature, some sampling tubes have seriously degraded microstructure, with the grade of pearlite spheroidization being 4.5, the carbides being clustered in chains, and have creep holes and intergranular cracks. And the more serious the microstructure deterioration is, the lower the hardness and the tensile strength are, and the worse the comprehensive mechanical properties are. On the other hand, the thickness of inner oxide layer has nothing to do with the degree of microstructure deterioration. The equivalent temperature of the sampling tubes during operation is close to the upper limit temperature stipulated by the material, and the residual creep life of the sampling tubes is more than 40 000 h.