3%Cr-Mo 鋼の諸性質におよぼす Ni, Cr および焼入冷却速度の影響

概要

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In the 3% Cr-Mo and 2.5%Ni-Cr-Mo steels which are to be used for large blower rotor and low-pressure turbine rotor shafts, were studied the effects of Ni contents (0∿2.5%) in the former and Cr contents (1.75 and 3%) in the latter on the continuous cooling transformation, and on the mass effect and mechanical properties when quenched at the cooling rate equivalent to the quenching of large rotor shaft. Results are summarized as follows : 1) The ferrite transformation curve is shifted to longer time and lower temperature with increase in Ni contents. The bainite transformation curve is also shifted to longer time and lower temperature with increase in Ni and Cr contents, the latter shift being negligibly small for Ni contents below 1.75%. 2) The transition temperature of the martensite and/or bainite with the tensile strength of 80∿90kg/mm^2, increases as the quenching rate decreases. This tendency is much pronouced especially at a very slow cooling rate. Increase in Ni contents tends to lower the transition temperature, but this change is very little between 1% and 1.75%. The transition temperature is increased with lowering quenching rate, especially at smaller Cr contents. 3) The transition temperatures of the test pieces quenched equivalently to large forgings agreeded fairly well with those of large rotor shafts.
社団法人日本鉄鋼協会の論文
1970-08-01