| 摘要 |
PURPOSE:To forge an ingot without bringing it to machine cutting, and to obtain its excellent inner quality and mechanical quality, by specifying a forging ratio in a specific temperature, and specifying the number of times of heating in all precesses. CONSTITUTION:An ingot 1 is heated to above a beta transas temperature, the ingot 1 is brought to cogging in the longitudinal direction, and a surface structure is crushed. Subsequently, by a repetition of upsetting and cogging, heat forging whose forging ratio is >= 5 is executed, in a heating temperature exceeding the beta transus temperature. Thereafter, in a heating temperature whose betatransus temperature is -50-100 deg.C, heat forging whose forge ratio is >= 3 is executed. Also, by setting the number of times of heating in all processes to at least three times, desired equi-axed fine particles are obtained.
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