Elucidation of controlling factors of hydrogen embrittlement in aluminum alloys

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K14018
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Niihama National College of Technology
• Principal Investigator: Manaka Toshiaki 新居浜工業高等専門学校, 環境材料工学科, 講師 (60805068)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: Al-Cu-Mg合金 / 水素脆化 / SSRT試験 / 湿潤ガス応力腐食割れ試験 / 粒界破壊

Outline of Final Research Achievements

It is known that hydrogen embrittlement(HE) susceptibility of aluminum alloys depends on alloy system. In order to reveal whether the high-resistance to HE in Al-Cu-Mg alloys results from microstructure near grain boundaries, HE susceptibility of Al-Cu-Mg alloys with various microstructures was evaluated using slow strain rate technique (SSRT) tensile test in humid air and humid gas stress corrosion cracking(HG-SCC) test. Although intergranular fracture was observed in some specimens in SSRT tensile test, the fracture surfaces were covered with fine dimples indicating ductile fracture manner. In HG-SCC test, crack propagation was not observed in any conditions. Therefore, it is concluded that Al-Cu-Mg alloys show high-resistance to HE regardless of microstructure.

Free Research Field

金属材料の水素脆化

Academic Significance and Societal Importance of the Research Achievements

アルミニウム合金の水素脆化機構の解明はさらなる高強度合金開発のためには避けては通れない課題であり、これまでに多くの研究が行われてきたが、Al-Cu-Mg合金に関する研究は少なく、金属組織が水素脆化感受性に及ぼす影響はあまり調べられていなかった。本研究で、金属組織を変化させ、異なる水素脆化評価方法においても、Al-Cu-Mg合金が耐水素脆化特性を示すことを明らかにしたことは学術的に意義があると考える。また、このことは同合金系を構造物へ適用する際に有用な基礎的知見であり、構造物の軽量化に寄与するものであることから、社会的意義も大きいと考える。