Effects of rare earth oxide on hardfacing metal microstructure of medium carbon steel and its refinement mechanism

• Published in: Journal of rare earths Vol. 29; no. 6; pp. 609 - 613
• Main Author: 郝飞飞 廖波 李达 刘利刚 淡婷 任学军 杨庆祥
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2011; State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University. Qinhuangdao 066004,China%State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University. Qinhuangdao 066004,China; School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China%School of Engineering. Liverpool John Moores University, Liverpool L3 3AF, UK
• Subjects: Coarsening; Ferrite; hard-face-welding metal; Hardfacing; heterogeneous nuclei; Inclusions; Medium carbon steels; Microstructure; Rare earth metals; rare earth oxide; Rare earth oxides; repair; 中碳钢; 堆焊金属; 异质晶核; 扫描电子显微镜; 断口观察; 显微组织; 稀土氧化物; 细化机制; repair; heterogeneous nuclei; hard-face-welding metal; microstructure; rare earth oxide
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/S1002-0721(10)60507-8

The electrodes for hardfacing medium carbon steel with six additions of rare earth oxide were developed in this work. By means of optical microscopy and scanning electron microscopy, the microstructure, inclusion and the fractograph of the hardfacing metal were observed. Then, the effects of rare earth oxide on microstructure and inclusions in hardfacing metal were analyzed. The effectiveness of rare earth oxide as heterogeneous nuclei of δ-Fe was calculated with the misfit theory. The results showed that, the microstructure of hardfacing metal was composed of ferrite and small amount of pearlite. The microstructure was refined at first and then coarsened with the increase of rare earth oxide addition. The fractograph was changed from brittle to equiaxed dimples, then became quasi-cleavage and cleavage gradually. The calculated results showed that, the ferrite grain size could be refined because that LaAlO3 as heterogeneous nuclei of δ-Fe was moderately effective, and the ferrite grain size was coarsened because the misfits between Ce2O3 and δ-Fe, Ce2O2S and δ-Fe were increased with futher increase of rare earth oxide addition.