• Journal of the Korean Society for Precision Engineering
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• v.14 no.7
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• pp.22-28
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• 1997

In this paper, We have studied internal quality incluiding chemical compositions, microscopic structure and nonmetalic inclusion of test material. We have analyzed dynamic characteristics of cutting resistence and compared chip treatment of the test material. In analyzing internal quality, all of the test material have typical ferrite+pearlite structure. But, nonmetallic inclusion has oxide and sulfide inclusion has oxide and sulfide inclusion in medium carbon steel, mainly sulfide inclusion is existed in S-free cutting steel. In Ca+S-free cutting steel, calcium aluminate and sulfide complex inclusion, had low-melting point, as deformation of sulfide and oxide inclusion is existed. Machining characteristics, cutting resistence is maximum in medium carbon steel. Chip treatement are excellent in S-free cutting steel, similar to the Ca+S free cutting steel and medium carbon steel.