Kyushu University · 공학
카와하라 유스이토 교수의 연구실은 고강도 아연화 스테인리스 스틸의 거동을 원자 척도에서 규명하는 데 초점을 맞추고 있습니다. 주로 질소 첨가가 스택형 결함 에너지(SFE)에 미치는 영향과 그가 비틀림 결함, 미세구조 형성, 고온/저온에서의 변형 거동에 어떻게 기여하는지 연구합니다. 고해상도 투과전자현미경(TEM)과 원자 프로브 탄소분석(APT)을 융합한 원자 척도 분석 기법을 핵심으로 하며, 이질적 원자 쌍(예: N-Cr)과 결함 간의 상호작용 메커니즘을 규명하고자 합니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
Austenitic stainless steels have superior room temperature and high temperature strengths, strongly influenced by stacking-faults in the steel microstructure. Nitrogen addition makes substantial contribution to room temperature and high temperature strengths, so it is essential to consider the effect of nitrogen on the stacking-fault energies (SFE) to understand strength mechanism of the steel and to enhance the strength. In this study, SFE were measured by weak-beam TEM method, and deformation
Combined addition of interstitial-substitutional elements has been acknowledged to contribute to the increase in the strengths of steels. For further improvements in mechanical properties, their atomic-scale interaction mechanisms with dislocations are required to be examined. In this study, both high-resolution transmission electron microscopy and atom-probe tomography were used to correlate interstitial-substitutional elements with dislocation characteristics in austenitic stainless steels. Th
The structures of carbon clusters and carbides in a low-carbon ferritic steel were investigated at atomic-scale by annular dark-field scanning transmission electron microscopy. In the low-carbon ferritic steel aged at 473 K for 1 h, some homogeneously dispersed ε-carbides were formed within the matrix as closely spaced granules aligned to <001> of the ferrite matrix, and others were heterogeneously formed on AlN precipitates. The ε-carbides formed on AlN precipitates were coexisted with carbon c
The stacking-fault energies (SFE) were measured by weak-beam TEM method, and deformation mechanisms in room and high temperature were characterized in terms of the effect of nitrogen addition on SFE in Si-added austenitic stainless steel (Fe-19%Cr-13%Ni-0.05%C-3%Si-x%N). Nitrogen addition resulted in decrease of SFE and changing the dislocation configuration from tangled to planar in room temperature. In high temperature, nitrogen addition resulted in the increase of dislocation density in the s
Abstract Interstitial-substitutional pairs have been acknowledged to contribute to the increase in the strengths of steels. For further improvements in mechanical properties, their atomic-scale structures and interaction mechanisms with defects are required to be examined. In this study, both high-resolution transmission electron microscopy and atom-probe tomography were used to correlate interstitial-substitutional pairs with defect characteristics in austenitic stainless steels. Three types of
Planar slips have been frequently recognized in nitrogen-added austenitic stainless steels, and often discussed in terms of stacking-fault energy (SFE). On the other hand, nitrogen addition promotes the formation of N-Cr short-range order (SRO), which has been proposed to cause the planar slips. In this study, a chromium-free Fe-N binary austenite with 2.4 mass% of fully solid-solutioned N was fabricated to simplify the relationship among deformation structures, SFE and N-Cr SRO. The Fe-N alloy
