700℃超超临界锅炉管用617B合金时效组织演变

Microstructure Evolution During Aging of Alloy 617B for 700 ℃ Ultra-Supercritical Boiler Pipe

摘要:

电站用合金的高温长期时效组织稳定性对合金的选材以及电站安全至关重要，本文详细研究了700℃超超临界锅炉管用617B合金在720 ℃/10000 h、800 ℃/2000 h和850 ℃/100 h时效和不同温度50 h时效过程中组织稳定性及力学性能变化。研究表明：617B合金在10,000 h长期时效末期组织稳定性较差，γ?相粗化且晶界上有有害相析出；温度对617B合金的组织稳定性影响较大，随着温度升高γ?相急剧粗化，晶内析出相发生转变；合金的硬度主要受γ?相析出规律的影响；720 ℃时效过程中晶内有拉链状析出相，其种类、结构有待进一步研究。

Abstract:

The microstructure stability during high temperature long-term aging of material for power plants is critical for the material choice and safety of power plants. In this paper the microstructure stability and mechanical properties of alloy 617B after 720 ℃/10000 h, 800 ℃/2000 h and 850 ℃/100 h aging and short term aging at different temperature are studied. The results show that the microstructure stability of alloy 617B after aging at 720 ℃ for 10,000 is relatively poor, γ? phase coarsens and harmful phase precipitates on grain boundary. Aging temperature has important influence on the microstructure stability of alloy 617B as γ? phase coarsened rapidly with the increasing of aging temperature and the intragranular precipitates transferred. The hardness of alloy 617B is mainly influenced by the precipitation rule of γ? phase. There are zipper-like precipitates in grain during 720 ℃ aging while the structure of phase needs further study.