| SUH660합금의 미세조직 및 기계적 특성에 미치는 2차 시효 열처리의 영향 |
| 김도훈1, 이유환2, 김정한1 |
1국립한밭대학교 신소재공학과
2태양금속공업㈜ 소재연구실 |
| Effect of Second Aging Treatment on the Microstructure and Mechanical Properties of SUH660 Alloy |
| Do-Hoon Kim1, You-Hwan Lee2, Jeoung Han Kim1 |
1Department of Advanced Materials Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
2Advanced Materials R&D Department, Taeyang Metal Industrial Co., Ltd., Ansan 15428, Republic of Korea |
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Received: 14 March 2016; Accepted: 10 May 2016. Published online: 5 October 2016. |
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| ABSTRACT |
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nSUH660 is a precipitation hardening stainless steel which has high strength at moderately high temperature. In this study, the effect of a secondary aging-treatment after the standard 720 °C heat-treatment was investigated. The Rockwell C hardness test with detailed TEM observerations was performed to study the steel’s hardening mechanism. The additional secondary aging treatment noticeably increased hardness and tensile strength. In particular, a secondary aging treatment at 630 °C for 24 hrs resulted in the maximum hardness of 35.5 HRC, which is higher than the hardness of a standard heat-treated sample by around 4 HRC. A transmission electron microscopy study revealed the size distribution of γ′ and h precipitates after standard aging treatment. In contrast, the n precipitate was not oberserved after the 630 °C secondary aging-treatment. Contrary to expectation, the γ′′ precipitate was not observed regardless of aging-treatment. The mechanism of the hardening process is discussed. |
| Keywords:
SUH660, superalloy, precipitation hardening, aging treatment, hardness |
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