Tribological properties of ultra-fine grained materials produced by surface severe plastic deformation

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04160
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18040:Machine elements and tribology-related
• Research Institution: Fukui National College of Technology
• Principal Investigator: Kato Hirotaka 福井工業高等専門学校, 機械工学科, 教授 (30311020)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: トライボロジー / 超強加工 / 滑りバニシング / 微細結晶粒材料 / 耐摩耗性

Outline of Final Research Achievements

Sliding burnishing process is a surface severe plastic deformation technique, in which the surface of the workpiece is subject to compressing and rubbing by the application of a ball as a tool. This process provides many advantages; burnishing generates a smooth surface by plastic deformation of surface irregularities without removal of material from the surface, and increases the surface hardness of the workpiece due to the microstructural evolution such as grain refinement, which in turn improves the wear resistance.
In the present study, the effects of burnishing process parameters such as force and speed on the surface roughness, microstructure and hardness of carbon steel were investigated. Also the present work was carried out to investigate effects of initial turned surface roughness on the burnished surface roughness and hardness. In addition the sliding wear properties of the burnished surface layers were studied using a ball-on-disk friction method.

Free Research Field

微細組織金属材料のトライボロジー

Academic Significance and Societal Importance of the Research Achievements

極めて大きな塑性ひずみを与える超強加工により作製可能となったナノ／サブミクロン微細結晶粒材料は、合金元素に頼らずに高強度であるため次世代の構造材料として注目されている。とくに本研究で提案した滑りバニシングは、材料表面が超微細化・ナノ組織化して硬度が上昇し、耐摩耗性が飛躍的に向上する。したがって、本研究で得られた、平滑化と高硬度化の両方を満足する最適な加工条件や加工前の表面性状が及ぼす影響に関する知見、さらにはその加工面の優れた摩擦摩耗特性に関する研究成果は、微細組織構造材料をトライボロジー分野に応用展開する上で大きな意義がある。