Alloys or metallic compositions – Ferrous – Lead – bismuth – selenium – tellurium or calcium containing
Reexamination Certificate
2006-03-21
2006-03-21
Yee, Deborah (Department: 1742)
Alloys or metallic compositions
Ferrous
Lead, bismuth, selenium, tellurium or calcium containing
C420S087000, C420S127000, C148S327000
Reexamination Certificate
active
07014812
ABSTRACT:
A sulfur-containing free-cutting steel for machine structural use, containing, in weight percent, 0.10 to 0.55% of C, 0.05 to 1.00% of Si, 0.30 to 2.50% of Mn, not more than 0.15% of P, 0.050 to 0.350% of S, more than 0.010% but not more than 0.020% of Al, 0.015 to 0.200% of Nb, 0.0015 to 0.0150% of O, and not more than 0.02% of N, and further containing, in weight percent, at least one selected from the group consisting of 0.03 to 0.50% of V, 0.02 to 0.20% of Ti and 0.01 to 0.20% of Zr, wherein the ratio S/O of the S content to the O content is 15 to 120, and at least one selected from the group consisting of an oxide, a carbide, a nitride and a carbonitride of Nb(see FIG.1) acts as nuclei for precipitation of MnS type inclusions. A sulfur-containing free-cutting steel for machine structural use is obtained by adjusting the chemical composition of steel and provides a sulfur free-cutting steel that does not contain lead but has a machinability and mechanical properties on a par with conventional lead-containing free-cutting steel.
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Fukuzumi Tatsuo
Uchibori Katsuyuki
Watanabe Motoki
Yoshimura Tsuneo
Flynn ,Thiel, Boutell & Tanis, P.C.
Mitsubishi Steel Mfg. Co. Ltd.
Yee Deborah
Yoshimura Technical Office Inc.
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