Development of hot stamping of age-hardened aluminium alloy sheet using contact heating without solution heat treatment

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04772
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Yokohama National University
• Principal Investigator: Maeno Tomoyoshi 横浜国立大学, 大学院工学研究院, 准教授 (80505397)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: アルミニウム合金 / ホットスタンピング / 溶体化処理 / 人口時効 / 接触加熱

Outline of Final Research Achievements

Hot stamping of age-hardened aluminum alloy using short-time heating was developed to apply 7xxx series aluminum alloy for automobile stamping products. The solution and age heat treatment were omitted. For the A7075-T6 aluminum sheet, the relationship between heating conditions and the hardness of formed products was obtained. The formability of contact heated aluminum alloy of 200 °C was investigated. The cylindrical cup of 1.8 in drawing ratio was successfully formed by short-time heating of 200 °C, even though fractured for 1.4 in drawing ratio in cold forming. The tensile strength, elongation, and fatigue bending strength of hot-stamped parts of 200 °C were equal to the as-received T6 sheet. In addition, hot stamping using T4 and T7 blank sheets was developed to decrease the springback and residual stress of formed products.

Free Research Field

金属成形

Academic Significance and Societal Importance of the Research Achievements

アルミニウム合金の中でも強度の高い7000系アルミニウム合金において，生産性の高いホットスタンピングが提案された．高比強度材の中でもマグネシウム合金やCFRPなどに比べ材料コストの低いアルミニウム合金は利用範囲が広く，炭素排出量低減のために必要となる自動車の軽量化において利用が期待されており，提案プロセスの社会的意義は高い．また，熱処理型アルミニウム合金の時効強化後の加熱プロセスや1分よりも短い短時間の加熱が機械的強度に及ぼす影響の研究は少なく，本研究で示した学術的意義は高い．