Improvement of hydrogen embrittlement resistance by thermomechanical processing in ultrahigh-strength TRIP-aided steels

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04743
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Tohoku University
• Principal Investigator: Hojo Tomohiko 東北大学, 金属材料研究所, 助教 (50442463)
• Co-Investigator(Kenkyū-buntansha): 秋山 英二 東北大学, 金属材料研究所, 教授 (70231834)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 水素脆化 / 残留オーステナイト / 熱間鍛造 / 超微細粒 / 機械的特性 / 超高強度鋼 / 変態誘起塑性

Outline of Final Research Achievements

Effects of thermomechanical processing on mechanical properties and hydrogen embrittlement resistance of the TRIP-aided steels were investigated.
Mechanical properties and hydrogen embrittlement properties of TRIP-aided steels were improved by the thermomechanical processing. These might be caused by the microstructure refinement and improvement of retained austenite characteristics due to the combination of hot forging and heat treatment.
The hot-forged TRIP-aided steels possessed excellent hydrogen embrittlement resistance in comparison with the conventional tempered martensitic steels. The excellent hydrogen embrittlement resistance of TRIP-aided steels was attributed to the refinement of microstructure because of the dynamic recrystallization during hot forging.

Free Research Field

構造材料および機能材料関連

Academic Significance and Societal Importance of the Research Achievements

超高強度鋼に熱間鍛造熱処理を施したときの微細組織形成挙動を明らかにすることによって，熱間鍛造熱処理時の動的再結晶挙動，オーステナイトのベイナイト変態挙動，炭素濃化挙動を明らかにできると期待される．また，超高強度鋼の水素脆化に及ぼす微細組織，および残留オーステナイト特性の影響を明確にすることにより，超高強度鋼の水素脆化メカニズム解明の一助となることが期待される．また，自動車用超高強度鋼の水素脆化を抑制し，さらなる高強度化を達成することによって，次世代の自動車用構造材料となると期待され．自動車の軽量化，小型化が達成され，燃費向上，温室効果ガス排出量削減が達成されると考えられる．