稀土元素La对碳锰纯净钢组织和冷却转变的影响

通过显微组织观察和对临界转变温度的测定，研究了稀土元素La对碳锰纯净钢组织和冷却转变过程的影响。结果表明，当镧含量较高时，纯净钢冷却转变组织粗化，形成魏氏组织的趋势增加，珠光体片层间距不均匀；在碳锰纯净钢的冷却转变过程中，随La含量的增加，先共析铁素体开始析出温度降低，析出速度加快，共析转变开始温度降低。镧在晶界的偏聚是造成碳锰纯净钢组织和相变过程变化的主要原因。

Effect of La Element on Microstructure and Cooling Transformation of Carbon-Manganese Purity Steels

The effects of rare earth element La on microstructure and cooling transformation of carbon-manganese purity steels were investigated by microstructure observation and phase transformation critical temperatures determination. The results show that La leads to a tendency of grain coarsening and forming widmanstatten structure, resulting in inhomogeneous interlamellar spacing of pearlite when La content is higher. During the cooling transformation process of carbonmanganese purity steels, the precipitation starting temperature of pro-eutectoid ferrite and eutectoid decreases and the precipitation speed increases with increasing La content. The reason above varieties on carbon-manganese steels is relative to La segregation in grain boundary.