항복비 제어기법을 활용한 냉간단조 제조공정 기술개발에 관한 연구

Abstract

This paper describes the development of a cold forging manufacturing process that utilizes the yield-ratiocontrol technique. Plastic deformation of the material is a serious challenge faced in cold forging of alloysteels. Often, this results in occurrence of overlaps and cracks on the surface and interiors of the product. Moreover, repeated annealing to ensure ease of machinability causes formation of an oxide layer and anabnormal microstructure layer on the surface resulting in quality degradation. To prevent this, we developedthe cold -forging manufacturing process that yields satisfactory mechanical properties while eliminating theneed for annealing and quenching. Through experiments and analyses, the raw material yield ratio,room-temperature tensile strength, effective hardening depth, and internal hardness were determined to verifythat the performance indicators we conform to the requirements. The development of cold forgingmanufacturing technology utilizing the yield-ratio control technique is expected to enable production ofhigh-quality cold-forged products at reduced costs owing to the elimination of the annealing and crude heattreatment processes which in turn could result in price competitiveness.