含窒素オーステナイト系耐熱鋼の時効後の室温靱性に及ぼす合金元素の影響(高温の組織と強度)(<特集>耐熱鋼・耐熱合金)

概要

論文の詳細を見る
The effects of C, N, Ni, Cr, Nb, Mo and B on the toughness after aging at 700/900℃ has been investigated in 19/25% Cr-8/22% Ni steels. The toughness after aging has been evaluated by V-notch Charpy impact test at room temperature. The main results obtained are as follows. (1) The toughness after aging was remarkably reduced when carbides, M_<23>C_6, and nitrides, Cr_2N, precipitated at grain boundary and twin boundary. Therefore the toughness strongly depended on the contents of C and N. Ni reduced the solubility of C and N, so that the addition of it in excess quantity promoted the precipitation of carbides and nitrides, and consequently reduced the toughness. (2) The addition of Nb or B in suitable quantity improved the toughness after aging, because those elements suppressed the precipitation of carbides and nitrides at twin boundary and simultaneously made the precipitates at grain bonudary to be fine and discontinuous. The addition of Mo within 1% slightly improved the toughness, but the addition of it over 1% reduced the toughness. The addition of much quantity of Mo promoted the precipitation of σ phase at grain boundary and consequently reduced the toughness remarkably.
社団法人日本鉄鋼協会の論文
1979-06-01