PURPOSE: To produce a steel for machine structural use, having high vibration damping capacity and excellent in strength and toughness.
CONSTITUTION: A steel, which has a composition consisting of, by weight, ≤0.02% C, ≤0.02% Si, ≤0.08% Mn, 0.05-1.50% Cu, 1.0-7.0% Al, ≤0.0080% N, and the balance Fe with inevitable impurities and containing, if necessary, 0.05-1.50% Ni, is used. A stock of this steel is heated to 1000-1300°C and hot- rolled at >900°C rolling finishing temp. Successively, the resulting hot rolled steel is cooled down to room temp. at ≥0.1°C/s cooling rate, heated and held at 800-1300°C, and subjected to intermediate heat treatment at >0.1°C/s cooling rate. Then, the steel is subjected to final heat treatment having ≥17.2×103 parameter Prepresented by equation P=T(20+logt) [where P, T, and (t) are absolute temp.(K), holding temp. (°C), and time (h), respectively], at 450-700°C. By this method, the steel for machine structural use, having high vibration damping capacity and excellent in toughness, can be produced.
OTA HIROKI
MORIKAGE YASUSHI
AMANO KENICHI
