国产Super304H钢高温持久后微观组织与性能

Properties and Microstructure Evolution of Domestic Super304H Steel during High Temperature Creep Rupture Testing

为促进国产Super304H钢的推广应用,采用硬度测试、金相组织分析、透射电镜(TEM)分析、扫描电镜(SEM)和能谱(EDX)分析等对国产Super304H钢在600、650、700℃高温持久后的微观组织及性能进行了试验研究。结果表明:在高温持久过程中,国产Super304H钢基体组织稳定,晶粒无明显变化,其硬度的升高主要与第二相的析出有关,析出相主要为ε-Cu、二次Nb(C,N)和M23C6,细小弥散的ε-Cu、二次Nb(C,N)使Super304H具有较高的强度。Super304H钢在高温持久过程中的组织老化主要表现为M23C6在晶界聚集、沿晶界呈链状分布,以及颗粒尺寸粗化。国产Super304H钢持久10 000 h后,其强度、硬度仍处于较高水平,组织状态良好。

In order to promote the popularization and application of domestically-made Super304H steel, the creep rupture specimens of the steel are analyzed by adopting Vickers hardness measurement, meiallographic structure observation, transmission electron microscope, scanning electron microscopy and energy spectrum analysis at the temperatures of 600 ℃, 650 ℃ and 700 ℃ respectively. The results show thai the matrix strncture of tile steel is stable during high temperature creep without grain growth. Its hardness increase is related to lhe second phase precipitation in high temperature creep, ε-Cu, secondary Nb （C, N） and M23C6 are lhe main precipitated phases in the steel during high temperature creel）, in which tile tiny e-Cu and seeondary Nb （C, N） keep the steel at high strength levels. The microstructure aging characteristies of tile steel show M23C6 gathering like chain on the grain boundary and size coarsening. After 10 000-h high temperature creep, the strengths and hardness of domestically-made Super304H steel are all maintained at high levels and with good microstructure.