论文部分内容阅读
采用L78 RITA淬火热膨胀仪、QUANTA400扫描电镜和JEM-2100透射电镜研究镧铈混合稀土对20MnCrNi2Mo耐磨铸钢过冷奥氏体连续冷却转变动力学及显微组织的影响,采用电感耦合等离子体质谱仪测定稀土的固溶量,通过透射电镜探索固溶稀土在钢中的存在状态,结合对La的界面扩散系数的测定、计算,综合分析镧铈混合稀土的作用机理。结果表明,镧铈混合稀土使20MnCrNi2Mo耐磨铸钢CCT曲线整体向右下方移动,促进了连续冷却转变过程中下贝氏体的形成,提高了淬透性,使得板条马氏体组织中孪晶亚结构增加。分析认为,固溶于钢中的稀土原子富集于晶界等晶体缺陷处,降低晶界能、阻塞扩散通道,推迟新相的形核-长大过程,进而影响组织转变。
The effects of lanthanum cerium mixed rare earths on the kinetics and microstructure of the continuous cooling transformation of 20MnCrNi2Mo wear-resistant cast steel under supercooled austenite were investigated by using L78 RITA quenching dilatometer, QUANTA400 scanning electron microscope and JEM-2100 transmission electron microscope. Inductively coupled plasma mass spectrometry Instrument was used to measure the solid solution amount of rare earth. The existence state of solid solution rare earth in steel was explored by transmission electron microscope. Combined with the determination of interface diffusion coefficient of La, the action mechanism of lanthanum cerium mixed rare earth was comprehensively analyzed. The results show that the mixed rare-earth lanthanum cerium causes the CCT curve of 20MnCrNi2Mo wear-resistant cast steel to move downward to the right, accelerates the formation of lower bainite during the continuous cooling transformation, increases the hardenability and makes the twin of the lath martensite Crystal structure increased. The analysis shows that the rare earth atoms dissolved in the steel are enriched in the grain defects such as grain boundaries, which can reduce the grain boundary energy and obstruct the diffusion channels and postpone the nucleation and growth process of the new phase, thereby affecting the organization transformation.