Patent ID: 6402858
Filing Date: 2002-06-11
Classification: C21D,C22C

Abstract:
A super-clean steel which has a chemical composition of, by weight, C: 1.1% or less, Si: 0.1-1.5%, Mn: 0.2-1.0%, Cr: 0.01-2.0%, Cu: up to 1.0%, Ni: up to 1.0%, Mo: up to 1.0%, W: up to 0.5%, Co: up to 1.0%, V: up to 1.0%, Nb: up to 0.1%, B: up to 0.01 %, and balance: Fe, and inevitable impurities, including P: up to 0.025%, S: up to 0.025%, and Al: up to 0.003%, and Caâ€”Alâ€”Si oxide inclusions having a composition defined by region (I) in FIG. 2 of the present application, wherein the area of non-metallic inclusions existing in the surface of the steel is not more than 15,000 &mgr;m2 per gram when the steel is melted by an electron-beam under the following conditions (per gram): an energy irradiation rate of 200 to 600 J/second, an irradiation time of 10 to 25 seconds, and an irradiation energy of 5,000 J or more, and solidified.