Reheat treatment process of mold is necessary when partial machining of the mold is required, such as shape correction for an existing mold. If defects such as cracks or significant deterioration of mechanical properties of the mold occur during reheat treatment, it is impossible to reuse the mold. In this study, reheat treatment was performed up to two times for STD11 tool steel, and microstructure and mechanical properties according to the reheat treatment were evaluated. Carbide fraction and grain size of prior austenite were almost unchanged after the reheat treatment. Hardness and impact toughness increased significantly after QT treatment, and these properties were maintained without significant change even after the reheat treatment. It is concluded that up to two iterations of reheat treatment does not cause deterioration of properties of STD11 tool steel. Based on these results, a mold for a face-lifted front bumper was manufactured through machining and reheat-treating of an existing mold.

Abstract
1. 서 론
2. 실험 방법
    2.1, 재열처리
    2.2. 미세조직 및 기계적 특성평가
3. 결과 및 고찰
    3.1. 재열처리에 따른 미세조직 변화
    3.2. 재열처리에 따른 기계적 특성 변화
    3.3. 금형 제작
4. 결 론
Acknowledgements
References

• 박기연(한국생산기술연구원 탄소경량소재응용연구그룹) | Gi Yeon Park (Carbon & Light Materials Application R&D Group, Korea Institute of Industrial Technology, Jeonju, 54853, Republic of Korea)
• 권의표(한국생산기술연구원 탄소경량소재응용연구그룹) | Eui Pyo Kwon (Carbon & Light Materials Application R&D Group, Korea Institute of Industrial Technology, Jeonju, 54853, Republic of Korea) Corresponding author
• 허기호(태왕테크 기업부설연구소) | Gi Ho Heo (Taewang Technology, Kimje, 54328, Republic of Korea)