저합금강의 이중 오스테나이징 템퍼링에서 냉각 속도에 따른 미세조직 및 기계적 특성 변화 |
김경후1, 장재호1, 김성환1, 김병준1, 손근용2, 남대근1 |
1한국생산기술연구원 동남지역본부 2인제대학교 나노융합공학부 |
Effects of Cooling Rate by Double Austenitizing Tempering Treatment on the Microstructure and Mechanical Properties in Low Alloy Steel |
Gyeong-Hoo Kim1, Jae-Ho Jang1, Sung-Hwan Kim1, Byung-Jun Kim1, Keun-Yong Sohn2, Dae-Geun Nam1 |
1Dongnam Regional Division, Korea Institute of Industrial Technology, Busan 46742, Republic of Korea 2Department of Nanoscience and Engineering, Center for Nano-manufactureing Inje University, Gimhae 50834, Republic of Korea |
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Received: 20 January 2017; Accepted: 24 March 2017. Published online: 1 August 2017. |
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ABSTRACT |
Spent nuclear fuel is stored and transported in cask bodies, but they become embrittled with the passage of time resulting in lattice defects due to neutron irradiation. Cask bodies made by the quenching and tempering (QT) treatment are not safe and are hard to store because of embrittlement caused by high levels of radiation and heat over long periods. Recently, it was shown that the double austenitizing tempering (DAT) treatment resulted in a significant improvement in strength and toughness as a result of austenite grain refinement. In this study, we evaluated the effects of DAT treatment for improving the mechanical properties of low alloy steel. We also investigated the effects of cooling rate on the DAT treatment. It was found that the charpy impact properties of the alloy were improved by the DAT treatment, which used water cooling comparing, compared to the QT heat treated specimen. As a result of microstructure analysis, it was determined that the grain size and carbide morphology were affected by mechanical properties such as the tensile, hardness and impact property. |
Keywords:
low alloy steel, DBTT, quenching, tempering, cooling rate |
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