Surface Nanocrystallization of Steel 20 Induced by Fast Multiple Rotation Rolling

作     者：Xingdong Yuan Bin Xu Yucheng Cai 

作者机构：School of Materials Science and EngineeringShandong University School of Materials Science and EngineeringShandong Jianzhu University 

出 版 物：《Journal of Harbin Institute of Technology(New Series)》 (哈尔滨工业大学学报（英文版）)

年 卷 期：2015年第22卷第5期

页      面：38-41页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

主　　题：fast multiple rotation rolling steel 20 surface nanocrystallization dislocation Cr-Rare earth-boronizing 

摘      要：In order to expand the application of steel 20 in precision device,fast multiple rotation rolling( FMRR) is applied to fabricate a nanostructured layer on the surface of steel 20. The FMRR samples are then Cr-Rare earth-boronized under low-temperature. The microstructure of the top surface layer is characterized by transmission electron microscopy( TEM). Microhardness of the top surface is measured by a Vickers microhardness tester. The boride layer is characterized by using scanning electron microscopy( SEM).Experimental results show that a nanostructured layer with their grain size range from 200 to 400 nm is obtained in the top surface layer. The microhardness of FMRR sample changes gradiently along the depth from about274 HV in the top surface layer to about 159 HV in the matrix,which is nearly 1.7 times harder than that of the original sample. The penetrating rate is enhanced significantly when the FMRR samples are Cr-Rare earthboronized at 600 ℃ for 6 h. Thickness of the boride layer increases to around 20 μm,which is nearly twice thicker than that of the original sample.