In this study, the direct water quenching technique is applied to validate the applicability of direct water quenching as a cooling method in the hot stamping process of 3.2 mm thick boron steel sheet. Cooling performance of conventional die quenching and direct water quenching is compared. Higher cooling rate is obtained by hot stamping with direct water quenching compared to die quenching. As the flow rate of cooling water increases, the cooling rate increases, and a high cooling rate of 71 oC/s is achieved under flow rate conditions of 0.8 L/min. Through direct water quenching, the cooling time required for sufficient cooling of the sheet is reduced. Full martensitic microstructure is obtained under flow rate condition of 0.8 L/min. Hardness increases with increasing flow rate. From these results, it is verified that the direct water quenching is applicable to the hot stamping of thick boron steel sheet.

Abstract
1. 서 론
2. 실험 방법
    2.1 직수분사냉각시스템 구성 및 설계
    2.2 직수분사 핫스탬핑 성형실험
    2.3 냉각속도 측정, 미세조직 관찰 및 기계적 특성 평가
3. 결과 및 고찰
    3.1 직수분사냉각 금형 냉각성능평가
    3.2 미세조직 및 기계적특성 평가
4. 결 론
References

• 박현태(한국생산기술연구원 탄소경량소재응용그룹/전북대학교 기계설계공학과) | Hyeon Tae Park (Carbon & Light Materials Application R&D Group, Korea Institute of Industrial Technology/Department of Mechanical Design Engineering, Jeonbuk National University)
• 권의표(한국생산기술연구원 탄소경량소재응용그룹) | Eui Pyo Kwon (Carbon & Light Materials Application R&D Group, Korea Institute of Industrial Technology) Corresponding author
• 임익태(전북대학교 기계설계공학과) | Ik-Tae Im (Department of Mechanical Design Engineering, Jeonbuk National University)