Other

Jfe Bars & Shapes Corporation

National Institute of Advanced Industrial Science and Technology

Tetsuo Shiraga

Toshiyuki Murakami

Kiyohito Ishida

Kunikazu Tomita

Katsunari Oikawa

Katsuhiko Kikuchi

Hiroshi Onoe

A low carbon resulfurized free cutting steel consisting of 0.04 to 0.15% of C, more than 0.10% and 0.70% or less of Si, 0.85 to 1.50% of Mn, 0.040 to 0.120% of P, 0.250% or more and less than 0.400% of S, less than 0.005% of Al, more than 0.0020% and 0.0120% or less of O, and more than 0.0070% and 0.0150% or less of N, all by mass percentage, and the balance of Fe and inevitable impurities, and satisfying a formula (1) and a formula (2), as follows:0.15%&#x2266;Si %+2&#xd7;P %&#x2212;(5&#xd7;Al %+10&#xd7;O %+3&#xd7;N %)&#x2266;0.75%&#x2003;&#x2003;(1), and([Mn %])/15&#x3c;S %&#x3c;([Mn %])/2&#x2003;&#x2003;(2).

Low carbon resulfurized free cutting steel

A low carbon free cutting steel can be obtained by allowing the steel to contain 0.02 to 0.15 mass % of C, 0.05 to 1.8 mass % of Mn, 0.20 to 0.49 mass % of S, more than 0.01 mass % and not more than 0.03 mass % of O, 0.3 to 2.3% of Cr, and the balance consisting of Fe and inevitable impurities, the Cr/S ratio falling within a range of between 2 and 6.

Free cutting steel

To provide a high-strength steel having a desired strength (800 N/mm or higher) for screws and bolts of a large diameter (M8 or larger) that also have a tapping ability, and a high-strength screw made from such a steel. The steel comprises (by % mass) C: 0.05 to 0.20, Si: 0.20 or less (not including 0), Mn: 0.5 to 2.0, P: 0.015 or less, S: 0.015 or less, sol. Al: 0.020 to 0.080, N: 0.0060 or less, Cr: more than 0.80 to 2.0 and the balance being iron and unavoidable impurities.

High strength screw

Growing community of inventors

Tokyo, Japan

Tetsuo Shiraga