汽轮机高温叶片用3325YC1钢中析出相的热力学计算及钢的成分优化

Thermodynamic Calculation for Precipitated Phases in 3325YC1 Steel Used for High Temperature Blade of Steam Turbine and Composition Optimizing for the Steel

利用热力学计算软件Thermo-Calc计算出不同温度下3325YC1钢中M_(23)C_6和M_2B析出相的含量,以及铬、钨、钼元素含量对这两种相析出温度和析出量的影响;在此基础上通过降低铬、钨、硼含量对钢的成分进行调整,并对成分调整前后钢的高温拉伸、疲劳和持久性能进行了对比试验。结果表明:铬是M_(23)C_6和M_2B相的主要形成元素,增加铬含量对这两种相的析出量没有影响;钨是M_2B的主要形成元素,随着钨含量增加,M_2B的析出量增加,但析出温度没有变化;硼含量增加能明显提高Cr_2B和M_2B相的析出量,但不影响它们的析出温度;钢的成分调整后基本不会影响它的高温瞬时拉伸性能和疲劳性能,其在620℃、10万h的Larson-Miller外推持久断裂强度仍高于100 MPa。

The contents of precipitated phases M_（23）C_6 and M_2B in 3325YC1 steel at different temperature were obtained by Thermo-Calc software,as well as the effects of Cr,W and Mo contents on precipitation temperature and content of the precipitated phases.Based on the above,the chemical composition of the steel was adjusted by decreasing the contents of Cr,W and B elements,and the comparative high temperature properties like tensile,fatigue and rupture tests for 3325YC1 steel with/without adjusting were carried out.The results show that Cr is the main element to form M_（23）C_6 and Cr_2B,but adding Cr content has no effects on precipitation contents of the two precipitated phases.W is the main element to form M_2B,with the increase of W content,the precipitation content raised,but the precipitation temperature is not affected.B can not change the precipitation temperature of Cr_2B and M_2B,but can obviously increase their precipitation contents.The high temperature tensile and fatigue properties of3325YC1 steel with adjusting has not affected basically,and 100 000 hour creep rupture stress at 620 ℃ is still higher than 100 MPa predicted by Larson-Miller parameter method.