マンガン・ニッケル・銅合金の焼き戻し硬化
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概要
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The Mn-Ni-Cu alloys have been studied by several authors (Dean et al., Cook and Alexander and Mishima). According to these authors, the Mn-Ni-Cu alloys show temper-hardening, and the maximum hardening effect is obtained in alloys containing equal proportions of Mn and Ni. In the present work the alloy (in the form of sheet or wire) containing 20% Mn, 20% Ni and 60%. Cu was studied. With respect to the means of preparing one-phase samples, it was found that not only quenching from temperatures higher than 550℃ but also cooling in air are sufficient for that purpose. The tensile strength, elongation, Vickers' hardness number and bending plasticity of the sheets that were cold rolled and then given low temperature anneal have been measured. The curve plotting VHN versus the annealing temperature shows maxima at 375℃ and 475℃ (Fig. 4 and 5). The samples were dead-annealed at 550℃ for 2 hours (in the atmosphere of hydrogen), and then the effect of annealng at 375℃ and 475℃ on the hardness was examined (Figs!8, 9 and 10); it was found that temper-hardening occurs more rapidly at 375℃ than at 475℃. This shows that temper-hardening at 475℃ is remarkable only when the samples were given cold work prior to the temper-hardening. Microscopic observation shows that in samples that were annealed at 375℃ minute particles are precipitated (Fig. 11 b, c, d), whereas the samples that were annealed at 475℃ are strongly etched compared with as-rolled samples, indicating that annealing at 475℃ causes extremely minute particles to be precipitated but their size is too small to be detected by an optical microscope. Dean published -the assumption that the temperhardening in the Mn-Ni-Cu alloys is probably connnected with ordering of MnNi. This opinion seems to require modification in the light of the present work. The temperature coefficient of the electric resistance of the wires prepared from the alloy that was studied in the present work was found to be very small, if they are adequately heat-treated (Fig. 12).
- 宇宙航空研究開発機構の論文
- 1956-08-10