Development of tailored hot stamping having high productivity using partial control of cooling history

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01749
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Toyohashi University of Technology
• Principal Investigator: MORI KEN-ICHIRO 豊橋技術科学大学, 工学(系)研究科(研究院), 特任教授 (80127167)
• Co-Investigator(Kenkyū-buntansha): 中川 佑貴 東京工業大学, 工学院, 助教 (50837739) ; 前野 智美 横浜国立大学, 大学院工学研究院, 准教授 (80505397) ; 安部 洋平 豊橋技術科学大学, 工学(系)研究科(研究院), 准教授 (60402658)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ホットスタンピング / テーラード / 冷却履歴制御

Outline of Final Research Achievements

In order to manufacture tailored parts with high strength and high ductility zones in hot stamping of ultra-high strength steel automotive parts, the cooling history was partially controlled, and a partial forming process in which the high strength zones are formed with partial dies in the previous stage, a partial forced cooling process of the high strength zones before forming and partial thermal insulating process of the high strength zones before forming were developed. In addition, a hot stamping process for manufacturing high strength parts by thickening of corners, a hot stamping process for manufacturing patchwork tailored parts by mechanically joining a main blank and patch, an approach for estimating tensile strength and total elongation from a punching test, dual-frequency ultrasonic cleaning with diluted phosphoric acid solution for removing surface oxide layers of hot-stamped uncoated steel sheets were developed.

Free Research Field

生産加工学

Academic Significance and Societal Importance of the Research Achievements

高強度部と高延性部を持つテーラード部材は自動車の軽量化と衝突安全性向上に大きく貢献し，その部材を製造する技術において生産性を高めることは産業界から望まれている．テーラード部材において高強度鋼部でマルテンサイト，高延性部でフェライトに変態させる冷却履歴を達成するためのホットスタンピングの工程は学術的に大きな意義がある．また，大きな塑性変形とダイクエンチングによる部材角部のマルテンサイト組織微細化と硬さ向上メカニズム，希釈リン酸水溶液を用いた２周波超音波洗浄による表面酸化層の除去メカニズムなどの解明は学術的に大きな意義がある．