二次硬化型 Ni-Cr-Mo-V 鋼の引張性質と破壊靱性について

概要

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The relation was studied between the tensile properties and plane strain fracture toughness of secondary hardening steels, using three experimental Ni-Cr-Mo-V steels with different carbon contents. The plane strain fracture toughness was estimated by the critical J-value obtained from precracked three-point bending tests. The results obtained could be summarized as follows : (1) The tensile strength and ductility of the present steels are dependent remarkably on the carbon content, this dependency being similar for all the aging temperatures studied. (2) The plane strain fracure toughness is also affected by the carbon content and aging temperature of the secondary hardening range. The aging temperature where the plane strain fracture toughness has a minimum value coincides nearly with that at which the ultimate tensile strength is the greatest. (3) The tensile ductility and plane strain fracute toughness derease with an increase in strength level. At a constant strength level, however, the tesile ductility has an increasing tendency with an increase in aging temperature and the plane strain fracture toughness shows a tendency contrary to that. (4) The above contrasting bevavior results from the difference in fracture modes, to which the multiaxial stress state near the precrack tip contributes.
社団法人日本鉄鋼協会の論文
1977-08-01