稀土元素对高碳合金钢显微组织与耐磨性的影晌

Effect of Rare Earth Element on the Microstructure and Wear Resistance of the High Carbon Alloy Steel

在焊接材料中加入了不同质量分数的稀土元素，通过焊接方式添加到高碳合金钢中，并取得重熔金属试样。采用X射线衍射仪分析其相组成，采用金相显微镜观察试样显微组织；采用洛氏硬度计测试试样宏观硬度，采用砂带式摩擦磨损试验机检测试样耐磨性；采用场发射扫描电子显微镜分析试样磨损表面。研究表明，焊接金属的组织由黑色针状马氏体、白色网状高合金马氏体及残余奥氏体组成。随着稀土元素在焊材中质量分数的增加，高合金马氏体在焊接金属中的含量随之增加，焊接金属的硬度和耐磨性相应提高；当稀土元素载体质量分数为3．44％时，焊接金属性能最优。稀土元素能够细化合金钢的晶粒，有效提高基体组织的强硬性，其在合金钢中催化形成的马氏体可以有效提高材料焊接部位的耐磨性。

Rare earth within La2O3 was added into welding metal. The microstructure of the welding metal was observed by optical microscopy. The phase structure was determined by X-ray diffraction. The hardness and wear resistance of the hardfacing metal were meas- ured by Rockwell hardness tester and abrasive belt type wear testing machine respectively. The worn-out surface morphology was observed by field emission scanning electron micro- scope. The results indicated that the microstructure of the hardfacing metal was composed of the black needle-like martensite, white reticular high alloy martensite and retained austenite. With the increase of rare earth addition, the amount of the high alloy martensite increases, so do the hardness and wear resistance of the hardfacing metal. They are both reach the max- imum when the La2 O3 addition is 3.44. The primary austenite grain will be defined with the La2O3 added, increase the strength and toughness of the matrix microstructure. Combined with the high alloy martensite, which as the wear resistance phase, contribute to the increase of the wear resistance of the hardfacing metal.