高炭素マルテンサイトにおける低温焼戻し挙動の多面的解析

Multi-aspect characterization of low-temperature tempering behaviors in high-carbon martensite

Zhang, Y.*; 宮本 吾郎*; 古原 忠*; 丸澤 賢人*; 工藤 航平*; 諸岡 聡  

Zhang, Y.*; Miyamoto, Goro*; Furuhara, Tadashi*; Marusawa, Kenji*; Kudo, Kohei*; Morooka, Satoshi

In this study, following our previous work on low-temperature tempering kinetics, multi-aspect characterization (in-situ neutron diffraction, TEM and 3DAP) via combining various traditional and advanced experimental approaches was performed, with an aim to thoroughly elucidate the low-temperature tempering behaviors and microstructural evolutions in martensite. As the result, the lattice parameters of a- and c-axes of martensite became increased and decreased, respectively, during continuous heating, resulting in continuous weakening of its tetragonality especially in the temperature range of the 1st stage of /-carbide precipitation (340 K 500 K). On the other hand, the lattice parameter of austenite stopped increasing at 450 K much earlier before the onset of the 2nd stage, indicated the occurrence of carbon depletion.