稀土对耐磨板NM400低温冲击韧性的影响

摘要：采用双精炼LF+RH的冶炼工艺和2250mm热连轧机组的一步Q&P工艺开发了稀土NM400热轧卷板，运用扫描电镜及能谱仪等分析手段研究了稀土对钢中夹杂物的变形、组织形态、晶粒度尺寸以及冲击韧性的影响，重点围绕微量稀土元素提高NM400低温冲击功进行机制分析。研究表明，通过添加微量稀土易于钢中［O］和［S］结合，形成近似球状的高熔点RE-S-O化合物，有效地降低MnS和Al2O3-CaO复合夹杂物的形成概率，且在钢液凝固过程中起到异质形核作用，细化产品的显微组织，提高耐磨钢的低温韧性，特别是在-60℃情况下，NM400稀土耐磨钢的横向冲击功较常规NM400耐磨钢提高了92.3%，弥补了常规耐磨钢低温韧性较差的不足，扩展了耐磨钢的使用条件。

Effect of rare earth on low temperature impact toughness of NM400 wear-resistant steel plate

The rare earth NM400 hot rolled coil was developed by double refining LF+RH smelting process and one step Q&P process of 2250mm hot rolling mill. The effect of rare earth on the inclusions modification, microstructure and low temperature impact toughness of NM400 was investigated by using scanning electron microscopy and energy spectrum analysis，focusing on the mechanism analysis of trace rare earth elements to improve the impact energy of NM400 at low temperature. The results show that by adding trace rare earths, which is easy to combine ［O］ and ［S］ in steel to form a approximately spherical RE-S-O compound with a high melting point, which effectively reduces the formation probability of MnS and Al2O3 CaO composite inclusions, and play a hetero nucleation role in the solidification process of molten steel, refining the microstructure of the product, improving the low temperature toughness of wear resistant steel. Especially at -60℃, the transverse impact energy of NM400 rare earth wear resisting steel is increased by 92.3% compared with conventional NM400 wear resisting steel, which makes up for the poor toughness of conventional wear resisting steel at low temperature and expands the use conditions of wear resisting steel.