Abstract: A hot rolled steel strip made by the steps including assembling a twin roll caster, forming a casting pool of molten steel having a free oxygen content between 20 and 75 ppm and having a composition such that the cast strip comprises by weight, greater than 0.1 and not more than 0.5% carbon, between 0.9 and 2.0% manganese, between 0.05 and 0.50% silicon, greater than 0.01% and less than or equal to 0.15% phosphorus, and less than 0.01% aluminum, counter rotating the casting rolls forming the steel strip, hot rolling the strip such that mechanical properties at 10% and 35% reduction are within 10% for yield strength, tensile strength and total elongation, and coiling the strip at a temperature between 300 and 700° C. to provide a majority of the microstructure comprising bainite and acicular ferrite. Alternatively, the steel may have between 0.20 and 0.60% copper and manganese as low as 0.08%.

Abstract: A hot rolled steel strip made by the steps including assembling a twin roll caster, forming a casting pool of molten steel having a free oxygen content between 20 and 75 ppm and having a composition such that the cast strip comprises by weight, less than 0.25% carbon, between 0.9 and 2.0% manganese, between 0.05 and 0.50% silicon, greater than 0.01% and less than or equal to 0.15% phosphorus, and less than 0.01% aluminum, counter rotating the casting rolls forming the steel strip, hot rolling the strip such that mechanical properties at 10% and 35% reduction are within 10% for yield strength, tensile strength and total elongation, and coiling the strip at a temperature between 300 and 700° C. to provide a majority of the microstructure comprising bainite and acicular ferrite. Alternatively, the steel may have between 0.20 and 0.60% copper and manganese as low as 0.08%.

Abstract: A high copper low alloy steel sheet less than 5 mm is made by preparing a molten melt producing an as-cast low alloy steel comprising by weight, 0.02 % to 0.3% carbon, 0.10% to 1.5% manganese, 0.01% to 0.5% silicon, greater than 0.01 % and less than or equal 0.15% phosphorus, less than 0.05% aluminum, more than 0.20% copper, less than 0.03 % tin, less than 0.10 % nickel, total oxygen level at least 70 ppm and usually less than 250 ppm, free oxygen content 20 to 70 ppm, the remainder iron and impurities, solidifying the melt into sheet less than 10 mm thickness in a non-oxidizing atmosphere to below 1080° C. Copper content may be between 0.2% and 2.0% by weight. The steel may have a corrosion index (I) of at least 6.0 in accordance with ASTM G101 where: I=26.01 (% Cu)+3.88 (% Ni)+1.20 (% Cr)+1.49 (% Si)+17.28 (% P)?7.29 (% Cu)(% Ni)?9.10 (% Ni)(% P)?33.39 (% Cu)2. The steel may be produced by twin roll casting, and may be less than 2 mm thickness.