Improvement of fatigue properties of metallic material by using surface modification technique Scanning Cyclic Press

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K14835
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Hokkaido University
• Principal Investigator: Fujimura Nao 北海道大学, 工学研究院, 助教 (40732988)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 表面改質 / 疲労特性改善 / 組織の微細化 / マグネシウム合金

Outline of Final Research Achievements

A new surface modification technique, termed a scanning cyclic press (SCP), has been recently developed. In this process, a metal surface is scanned with a vibrating indenter using a servo control method, which can cyclically apply a variable and precise compressive load. This study applied an SCP to magnesium alloy AZ31 to investigate the effects of the SCP processing parameters, such as the magnitude of the compressive load and the number of cyclic loading, on the alloy’s fatigue property and the changes in the microstructure. The SCP created the surface layer whose microstructure included nanocrystallized grains, and it improved the fatigue properties of AZ31. The grain size and the depth of the nanocrystalline surface layer were different due to SCP processing parameters: for example, the larger compressive load created the deep nanocrystalline layer in a short time.

Free Research Field

材料強度学

Academic Significance and Societal Importance of the Research Achievements

SCPは金属表面に振動圧縮負荷を走査することで表層を改質する新しい表面改質技術である．本手法では圧縮負荷の大きさ，繰返し数，走査速度など種々の加工パラメータを調整することで改質組織や疲労特性改善等の効果を得るが，これらが改質機構や組織，諸特性に及ぼす影響は十分に明らかになっていない．SCPは高精度に制御された加工を表面に施すことで材料の諸特性を改善することができるため，機構に基づいて合理的に加工条件を設定し効果を得ることができれば，例えば新材料導入の期間短縮や，強度に関しては弱点がある機能材料を導入できるようになるなど，材料の適用範囲を拡大し，優れた特性を有する機器・構造物の実現が期待できる．