Title: Low carbon calcium-sulfur containing free-cutting steel

Abstract: Low carbon calcium-sulfur containing free-cutting steel exhibiting improved machinability is disclosed. The said steel consists essentially of 0.03 to 0.10% carbon, up to 0.3% silicon, 0.8 to 1.5% manganese, 0.04 to 0.10% phosphorus, 0.20 to 0.45% sulfur, 0.0003 to 0.0050% calcium and the remainder being iron and inherent impurities such as copper, nickel, chromium and nitrogen; and is prepared by regulating the composition of the steel so that the value of theoretical Brinell hardness of the steel matrix, which is determined on the basis of the content of carbon, silicon, manganese, phosphorus, sulfur, copper, nickel, chromium and nitrogen in the steel, to a value between 110 and 130, and by forming and maintaining in the range of from 100 to 500 grams per steel-ton oxide inclusions of type JIS-A2 (ASTM-C) which soften or fuse at a temperature not higher than 1400.degree.C.

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Inventors: Itoh, Tetsuro (Tohkai, JA)
Takahashi, Tetsuo (Nagoya, JA)
Yamano, Kiyoichi (Tohkai, JA)

Application Number: 612946
Filing Date: 1975-09-12
Publication_date: 1976-08-10
Assignee: Daido Seiko Kabushiki Kaisha (Nagoya, JA)
Primary Class(es): 420/84
Other Classes:
US Patent Ref:

2484231	Oct, 1949	Kent	75/123.
3723103	Mar, 1973	Kato et al.	75/123.
3844773	Oct, 1974	Yamakoshi et al.	75/123.

Other Refs: 1,270,646

Apr, 1972	UK

Primary Examiner: Steiner, Arthur J.
Assistant Examiner:
Attorney: