| Title |
Effect of Second Aging Treatment on the Microstructure and Mechanical Properties of SUH660 Alloy |
| Authors |
김도훈(Do-Hoon Kim); 이유환(You-Hwan Lee); 김정한(Jeoung Han Kim) |
| DOI |
https://doi.org/10.3365/KJMM.2016.54.10.716 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
SUH660; superalloy; precipitation hardening; aging treatment; hardness |
| Abstract |
SUH660 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 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 election microscopy study revealed the size distribution of γ′ and h precipitates after standard aging treatment. In contrast, the 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. |