Inhomogeneous Hardness Distribution of High Pressure Torsion Processed IF Steel Disks

Yuepeng Song, Wenke Wang, Dongsheng Gao, Hyoung-Seop Kim, Eun-Yoo Yoon, Dong-Jun Lee, Chong-Soo Lee, Jing Guo

Department of Materials Sci- ence and Engineering, Pohang University of Science and Technology, Pohang, Korea.
Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, Korea.
Mechanical and Electronic Engineering College, Shandong Agricultural University, Tai’an, China.
Shandong Provincial Key Laboratory of Horticultural Machineries and Equipments, Shandong Agricultural University, Tai’an, China..

DOI: 10.4236/msa.2012.34034                

Abstract

The inhomogeneous hardness distribution of high pressure torsion (HPT) processed IF steel disks along different directions is investigated. The results indicated that there exists inhomogeneous distribution in HPT processed IF steel disks, giving lower hardness in the center and higher hardness in the edge regions. However, on the axisymmetrical section testing plane of the disks’ thickness direction, there is a soft zone near the surface of disks. Further results from radius testing plane of different depths from the surface of HPT processed disks show that the inhomogeneity rules of hardness distribution on the radius direction are similar to that on the thickness direction. Compared with the initial state, different stages of HPT (compression and compression + torsion) can both remarkably increase the hardness of IF steel disks. Microstructure investigation results can give a well support to verify the rules of hardness distribution, showing hardly no change of grains in center and sever plastic deformation in edge. The inhomogeneous distribution of stress and strain with the huge friction between anvil and disks in the process of HPT play an important role of hardness and microstructure distribution.

Keywords

Hardness Distribution; High-Pressure Torsion (HPT); IF Steel; Inhomogeneous

Conflicts of Interest

The authors declare no conflicts of interest.

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