Abstract
Usually the burnishing process is used to achieve small surface roughness. Surface roughness and residual stress also can be improved by the burnishing process. In this study, the burnishing tool that rubs on the machined surface with high rotating speed is proposed, and the enhancement of the material/mechanical properties on the surface is reported. The tip of the burnishing tool stirs within the thin surface layer under rather high strain rate in this process. Two kinds of tool tips were employed, which are the cemented carbide and PTFE (Teflon). Firstly, after the friction stir burnishing on 0.45% carbon-steel with the carbide tip, very hard layer over 800HV was appeared. The thickness of the hardened layer is 20μm〜30μm. Secondly, aluminum alloy 7075-T651 was burnished with the PTFE tip. Then the PTFE could be coated on the aluminum and the frictional coefficient of the surface was decreased. In addition, the surface hardness increased from 173HV to 215HV.
