A cast carbon steel strip is prepared by continuously casting in a twin roll caster and cooling to transform the strip from austenite to ferrite at a temperature range between 400null C. and 850null C. at a cooling rate of not more than about 100null C./sec, such that the strip has a yield strength of greater than 450 MPa. The cast strip before cooling is passed through a hot rolling mill to reduce the thickness of strip by at least 15% and up to 50%.