PURPOSE: To provide a free cutting steel which satisfyes simultaneously the machineability in the stage of machining a high-speed steel tool and a sintered hard alloy tool, by regulating the total content of B in a steel contg. C, Si, Mn, P, S, N, and regulating the number of inclusions such as B2O3, MnO.nB2O3, of a specific length or above per unit section in the rolling direction of the steel material.
CONSTITUTION: A steel consisting essentially of ≤0.13% C, ≤0.03% Si, 0.6W 0.9% Mn, ≤0.035% P, ≤0.035% S, ≤0.005% N is provided. The total content of B in the steel is 0.005W0.05%, and the steel contains inclusions of ≥1 kinds among B2O3 inclusions (A), MnO.nB2O3 (n=1,2,3) inclusions (B) and composite inclusions of A and/or B and MnS, SiO2, Al2O3 (C). The inclusions of ≥1 kinds among the A, B, C of ≥1μm length are contained at 100W600 pieces in total of ≥1 kinds for each 1mm2 section in the rolling direction of the steel material. This free cutting steel has excellent mechanical properties in addition to the above-described characteristics.
KATAYAMA AKIRA
IMAI TATSUYA
| JPS57143435A | 1982-09-04 | |||
| JPS4959720A | 1974-06-10 | |||
| JPS5077211A | 1975-06-24 | |||
| JPS5354114A | 1978-05-17 |