| 다이캐스팅 공정에 사용된 개량형 STD61 열간 금형 표면의 미세조직에 관한 연구 |
| 유하영1, 이승준1, 강민우1,2, 이석진1, 양원존3, 정재석4, 김병훈5, 이영국1 |
1연세대학교 신소재공학과
2현대자동차 소재기술개발팀
3재료연구소 산업지원/안전본부
4두산 중공업(주) 기술 연구원
5두산 중공업(주) 주단BG |
| Study on the Surface Microstructure of a Modified STD61 Steel Mold Used for the Die Casting Process |
| Ha-Young Yu1, Seung-Joon Lee1, Minwoo Kang1,2, Suk-Jin Lee1, Won Jon Yang3, Jae Suk Jeong4, Byung-Hoon Kim5, Young-Kook Lee1 |
1Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
2Research and Development Division, Hyundai Motor Company, Hwaseong 18280, Republic of Korea
3Industrial Support/safety divisions, Korea Institute of Materials Science, Changwon 51508, Republic of Korea
4Corporate R&D Institute, Doosan Heavy Industries & Construction, Changwon 51711, Republic of Korea
5Casting & Forging BG, Doosan Heavy Industries & Construction, Changwon 51711, Republic of Korea |
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Received: 2 March 2016; Accepted: 7 April 2016. Published online: 5 September 2016. |
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| ABSTRACT |
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The surface microstructure and crack formation of an aluminum die-casting mold were investigated. The mold was made of a modified STD61 steel, and was used for more than 165,000 cycles. The mold surface consisted of four layers; an oxidized layer, a decarburized layer, a network carbide layer and a tempered martensite matrix. The depth down to the hardest network carbide layer was ~200 μm. Inside the matrix, M3C transition carbides were dissolved so that solute C joined pre-existing M23C6 and MC carbides to make them coarse. About 60% of thermal fatigue cracks had a depth less than 200 μm due to the hard network carbide layer, which obstructed the propagation of cracks. Cracks of over 200 μm were filled with oxide wedges of Al and Si which was which flown from the molten alloy as well as the Fe oxide. |
| Keywords:
alloys, casting, microstructure, scanning electron microscopy (SEM), thermal fatigue crack |
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