大型特殊鋼材の軟化燒鈍への等温變態の應用 (II)

概要

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In this second report, experiments carried out on thick forgings were given. The form of the forgings was the cylinder, and dimensions were outer dia. 660, inner dia. 480 and length 4500mm. The isothermal annealing operation consists in (1) heating the steel to a temperature just above its Ac range (2) cooling in air from γ state to the predetermined subcritical point (3) charging the steel into the furnace kept at the predetermined temperature and keeping the temperature constantly for a given time (4) cooling from that temperature to the atmospheric temperature in air. The producer gas fired furnace was used. The results obtained were summarized as follows ; (1) The isothermal annealing operation of low alloy steel thick forgings is quite easy. (2) The time required for this annealing process is 1/2 or less of the ordinary process. (3) The annealed structure is satisfactorily and uniformly softened. (4) The isothermal annealing develops the machinability of steel on account of its low hardness. (5) This new annealing method has no bad influence upon the heat treating operation after annealing and mechanical properties after hardening and tempering.
社団法人日本鉄鋼協会の論文
1949-11-25