Inconel 740H在700℃关键部件验证试验平台中的性能演变研究

Study on the Performance Evolution of Inconel 740H during Operation on the700 ℃ Component Test Facility

摘要:

为了进一步评估700℃先进超超临界火电机组选材的可用性和选材方案的科学性，对在华能南京电厂700℃关键部件验证试验平台上运行的候选管样进行定期取样和检测。采用力学性能测试和显微组织分析相结合的方法，对不同运行时间（0 h, 10000 h，24000 h）的Inconel 740H过热器管进行测试、对比和分析。研究结果表明：Inconel 740H在室温和700℃高温的屈服强度和抗拉强度随服役时间延长缓慢降低；在运行10000 h后，室温和高温冲击吸收功降幅显著，但当服役时间进一步延长至24000 h时降幅较小。显微组织方面，随着服役时间的延长，Inconel 740H的变化主要表现在晶界碳化物M23C6的长大变多及晶内γ′相的粗化。总体来说，Inconel 740H在运行24000 h后的力学性能和组织与演化均趋于稳定。

Abstract:

In order to further evaluate the scientificity and availability of materials selection scheme of the advanced 700℃ ultra-supercritical (700 ℃ A-USC) thermal power units, regular sampling and testing were conducted on the candidate tubes operating on the 700℃ A-USC test bed of Huaneng Nanjing Power Plant. Three groups of Inconel 740H superheater tubes with different operation time (0 h, 10,000 h, 24,000 h) were sectioned and machined, and then their mechanical properties and microstructure characteristics were evaluated by means of OM, SEM, TEM. Results show that the R_p0.2 and R_m of Inconel 740H at room temperature (RT) and 700℃ decreased slowly with the extension of operation time. The impact absorbing energy at room and high temperature both decreased significantly from original aging state to operation for 10,000 h, but when the operation time further prolonged to 24,000 h, only slight decrease was observed. The microstructure evolution of Inconel 740H was mainly manifested in the increase of grain boundary carbide M23C6 and the coarsening of γ′ particles. In general, Inconel 740H boiler tubes exhibited good mechanical properties and microstructure stability during operation.