中文摘要：

回顾了国家＂八.五＂项目的＂稀土合金钢轨的研制＂和＂十.五＂项目的稀土重轨钢机理研究。介绍了前者测量的研究钢性能、后者的内耗等研究和两者的相关观测结果,基于＂十.五＂项目的机理研究和相关的观测结果,从微观（原子）、介观（位错及其原子气团）、宏观（组织参量）等层次和上线轨承载时的应力分布方面,讨论和阐明了加稀土增强钢轨的使用硬化性,提高钢轨的耐磨和抗接触疲劳性能,以及稀土抑制钢轨的核伤、栓孔开裂和轨腰损伤等使用性能的机理。

英文摘要：

The subject entitled ＂ The Research and Development of the Rail of the Steels Alloying with Rare Earth＂ in the national 8th Five Year science program and the subject for mechanism study of the rail steels of rare earths in the 10th Five Year program are reviewed.The results of the properties measured by the ＂8·5＂ subject and of the mechanisms study for the ＂10·5＂subject,as well as of the related observatious in both the ＂8·5＂ and ＂10·5＂ subjects are introduced.The mechanisms that improve the service performents of the rails by the addition of rare earth elements,including the enhancement of the service hardenability,the improvement of the resistances in both the wear and the contact fatigue,the inhibitions of nucleation damage,bolthole cracking as well as rail waist damage etc are discussed and clarified,based on an analysis of stress distribution in a rail loaded,and on a microscopic scale（e,g,atom dimension）,a mesoscopic scale（e.g.dislocation,Cottrell atomsphere） and a macroscopic scale（e.g.structural parameters） respectively.