Ni-20Cr-20W 系合金の高温時効組織

概要

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High temperature aging structures and age hardening of Ni-20Cr-20W alloys developed as the superalloys for the nuclear energy steelmaking, and effects of C and Zr additions to the alloys and the effect of preheat treatment on these properties were studied. M_6C, α-W and two kinds of M_<23>C_6 having different lattice parameters were found as precipitates in the alloys. M_<23>C_6 whose lattice parameter was around 10.7A precipitated in the early stage of aging at 700℃-1150℃, and the carbide changed to M_6C at higher temperature than 1000℃, but it remained as a stable carbide at lower temperature than 900℃. α-W precipitated at 800℃-1100℃ after precipitation of M_<23>C_6 and it disappeared with increase of M_6C. M_<23>C_6 having the larger lattice parameter (10.9A) precipitated transitionally in aging stage of 26×10^3 in Larson Miller parameter at 900℃ and 1000℃. Age hardening corresponded to the precipitation of M_<23>C_6 and it was reduced by the double pre-heat-treatment. Zr addition and amount of C influenced on the aging structure and age hardening. Zr seemed to be a favorable element to stabilize the carbide.
社団法人日本鉄鋼協会の論文
1977-12-01