【摘要】 应用高分辨TEM,SEM和XRD研究碳锰洁净钢中镧和铈的存在形式、分布以及在晶界的行为。研究结果表明,镧和铈在洁净钢中存在固溶态、稀土夹杂物和稀土第二相。固溶稀土偏析在晶界,洁净钢中稀土仍有净化钢液和变质夹杂的作用。适量稀土能减少S和P在晶界的偏析,净化晶界提高钢的冲击韧性。过量稀土在晶界产生有害的稀土第二相,导致性能显著降低。更多还原

【Abstract】 In carbon manganese clean steel,the behaviors of La and Ce on grain boundaries were investigated by high-resolution transmission electron microscopy(HRTEM),SEM,EDS and XRD analysis.The existent phases of RE have solid solution La or Ce,RE inclusion and RE second phases(RE-Fe-P,Fe-La,Fe-La eutectic and FeCe phase) in clean steel.The dissolved La or Ce segregates in the grain boundaries,which reduces the segregation of both S and P on grain boundaries at suitable RE content.It improves the strength of grain boundaries and enhances the impact toughness of steel obviously.La and Ce still have purifying effect in molten steel and modify inclusion in clean steel.While excess La or Ce,La-Fe-P, La-P and Fe-La eutectic or Ce-Fe-P and Fe-Ce intermetallic compound can form along grain boundaries.It leads to decrease of the impact energy of steel significantly.更多还原