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 the Key Component Test Facility at 700 ℃

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、10 000、24 000 h)的Inconel 740H过热器管进行测试、对比和分析。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的延长缓慢降低;在运行10 000 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24 000 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,Inconel740H在运行24000h后的力学性能和组织的演化均趋于稳定。

In order to further evaluate the scientificity and availability of materials selection scheme of the advanced ultra-supercritical at 700 ℃(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 740 H superheater tubes with different operation time(0, 10 000, 24 000 h) were tested and analyzed, and then their mechanical properties and microstructure characteristics were investigated by OM, SEM, TEM. The results show that the Rp0.2 and Rm of Inconel 740 H at room temperature(RT) and 700 ℃ decrease slowly with the extension of operation time. The impact absorbing energy at room and high temperature both decrease significantly from original aging state to operation for 10 000 h, but when the operation time further prolongs to 24 000 h, only slight decrease is observed. The microstructure evolution of Inconel 740 H is mainly manifested in the increase of the grain boundary carbide M_(23)C_(6) and the coarsening of γ′ particles. In general, Inconel 740 H boiler tubes exhibit good mechanical properties and microstructure stability during operation.