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研究了C和Nb含量对TP347HFG钢在650℃析出相参量(成分、体积分数和尺寸)和持久寿命的影响.对ASME成分范围内的2种不同C和Nb含量的TP347HFG钢在650℃,230和150 MPa条件下进行持久实验,持久寿命分别为199,420 h和2426,8837 h,其中C含量较低Nb含量较高的样品持久寿命较长.对持久管样的EPMA-EDS+MPSM和TEM-EDS分析表明,较低的C含量和较高的Nb含量对应较少的M_(23)C_6和较多的MX,并阻碍了M_(23)C_6的聚集粗化,同时基体中可保留较多的Cr,有利于延长持久寿命.此外,运用热力学软件Thermo-Calc分析了在500-1300℃范围内C和Nb组合含量的变化对各相成分和体积分数的影响,与实验结果相吻合.
The effects of C and Nb content on the phase transition (composition, volume fraction and size) and the long-term life of TP347HFG steel at 650 ℃ were investigated. Two kinds of TP347HFG steel with different C and Nb contents within the ASME composition range were tested at 650 ℃, 230 And 150 MPa, the long-term life expectancy was 199,420 h and 2426,8837 h, respectively, of which samples with higher content of Nb and lower content of C had a longer lasting life.The long-life EPMA-EDS + MPSM and TEM- EDS analysis showed that lower C content and higher Nb content correspond to less M_ (23) C_6 and more MX, and hinder aggregation and coarsening of M_ (23) C_6, while more Of Cr, which is in favor of prolonging the long-term life.In addition, thermodynamic software Thermo-Calc was used to analyze the influence of the content of C and Nb in 500-1300 ℃ on the composition and volume fraction of each phase, which is in good agreement with the experimental results.