pISSN : 1598-706X / eISSN : 2288-8381
한국주조공학회지 (32권1호 32-37)
The Repeat Heat Treatment Behavior of Double Remelted Fe-Co Ultra-high Strength Steel. - Part. 1 Microstructure Control
Fe-Co기 고인성 고강도강의 반복 열처리 거동 - Part 1. 조직제어
Bo-Hee Yoon, Kyoung-Tae Park*, Tae-Hyuk Lee, Jae-Hoon Kim**, Hong-Kyu Kim***, Seong Lee***, Jong-Hyeon, Lee*
Chungnam national university, *Graduate school of green energy technology, Chungnam national university, **Department of mechanical engineering design, Chungnam national university, ***Agency for defense development
In this study, microstructural evaluation was carried out on secondary hardening type ultrahigh strength steel, Fe-Co-Ni composition. This paper as a first part of whole research presented the microstructural behavior by cyclic heat treatment. The cyclic heat treatment method includes normalizing, stress relieving, solution treatment and aging. Especially, solution treatments performed triple times to get maximized solution hardening. Phase transformation and microstructure were observed by using optical microscope (OM), Electron back-scattered diffraction (EBSD) and X-ray stress analyzer. During the triple solution treatment, size of grain boundary was dramatically decreased by generating a packet from the martensite transformation of residual austenite in the inner part of grain, whereas the hardness increase was not significant.
Ultra high strength steel, Fe-Co-Ni, Microstructure.
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