| 摘要 |
PURPOSE:To enable forging without any micro-defect, at the time of forging a hard working material such as Ni based superalloy, etc., by making the rolling reduction between the initial stage and the middle stage larger than the rolling reduction between the middle stage and the last stage to utilize the superplasticity by minimizing the microstructure of the superalloy material. CONSTITUTION:At the time of forging the hard working material such as Ni based superalloy, in the period between the initial stage and the middle stage of the forging, when the pressure receiving area of the material is relatively small, in the limits of the strain to generate no microcruck, the working is performed by about 50% of the rolling reduction and by a high strain rate by 5X10<-4>/S-5X10<-2>/S to promote the minimizing the microstructure of the material and to control rapid increasing the load between the last stage and the completion of forging. Then, the strain rate of forging in the range of the middle stage - the last stage - the completion is reduced than the strain rate at the preceding and initial stages to extinguish defects such as microvoid, etc., generated in the forging stage and to simplify manufacturing the good quality of the forgings.
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