Nucor Corporation
Hot rolled light-gauge martensitic steel sheet and method for making the same

Abstract:

A hot rolled light-gauge martensitic steel sheet made by the steps comprising: (a) preparing a molten steel melt comprising: (i) by weight, between 0.20% and 0.35% carbon, less than 1.0% chromium, between 0.7% and 2.0% manganese, between 0.10% and 0.50% silicon, between 0.1% and 1.0% copper, less than 0.05% niobium, less than 0.5% molybdenum, and silicon killed containing less than 0.01% aluminum, and (ii) the remainder iron and impurities resulting from melting; (b) solidifying at a heat flux greater than 10.0 MW/m.sup.2 and cooling the molten melt into a steel sheet less than 2.0 mm in thickness in a non-oxidizing atmosphere to below 1080.degree. C. and above Ar.sub.3 temperature at a cooling rate greater than 15.degree. C./s; and (c) hot rolling the steel sheet to between 15% and 50% reduction and rapidly cooling.