超超临界电站用617合金的组织特征及平衡相析出规律

Microstructure and Thermodynamic Calculation on Equilibrium Precipitated Phases of 617 Alloy for Advanced Ultra-supercritical Power Plants

摘要:

617合金是700 ℃以上超超临界燃煤电站的备选材料，具有优越的高温持久和耐氧化性能。本文利用热力学计算软件Thermo-Calc及相应的Ni基数据库，对617合金的平衡析出相规律进行了计算分析。结果表明，该合金主要平衡析出相包括γ′、σ、μ相以及碳化物M6C和M23C6，Ti对γ′相析出量的影响比Al更显著。对617合金标准热处理态的微观组织观察显示，组织均匀，晶界上有连续片状碳化物，再经1180 ℃/1 h固溶处理后，碳化物部分回溶，在晶界上呈颗粒状分布

Abstract:

As the candidate materials for advanced ultra-supercritical power plants, 617 alloy has superior mechanical properties and resistance ability against oxidation at a high temperature. In this paper, equilibrium precipitated phases of 617 alloy were calculated by Thermo-Calc software. The results show that the equilibrium phases include γ′, σ, μ, M6C and M23C6. The amount of γ′ is more sensitive to Ti than Al. Furthermore, this paper analyzed the microstructure features of 617 alloy as standard heat-treated. It is shown that 617 alloy has equiaxed grains and continuously precipitated carbides which are observed along the grain boundary. After solution treatment (1180 oC/1 h), part of the carbides re-dissolves and carbides become discontinuously distributed at the grain boundary