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US 4,398,970 AGranted
Titanium and vanadium dual-phase steel and method of manufacture
AssigneeBethlehem Steel Corporation
InventorsArnold R. Marder, Bruce L. Bramfitt
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AssigneeBethlehem Steel Corporation
InventorsArnold R. Marder, Bruce L. Bramfitt
Estimating the term…
This invention is directed to a method and to the resulting product, wherein said product is a low-carbon dual phase steel having a combination of high strength, good ductility and a YS/TS ratio .ltoreq.0.6. The method includes the steps of (1) preparing an Al-killed steel consisting essentially of 0.05 to 0.15 wt. % C, up to 2.0 wt. % Mn, up to 1.0 wt. % Si, 0.03 to 0.15 wt. % V and a sufficient amount of titanium to "getter" the excess sulfur and nitrogen, with the balance essentially being iron, where the titanium addition should be at least equal to the atomic percent of the sulfur plus nitrogen, but no more than about 1.6 times, (2) intercritically annealing such steel within the .alpha.+.gamma. temperature range, and (3) cooling to room temperature.
A high-strength dual-phase steel consisting essentially of, by weight 0.07-0.12% carbon, 0.50-1.60% manganese, 0.30-0.70% silicon, up to 0.020% phosphorus, up to 0.020% sulfur, up to 0.008% nitrogen 0.02-0.06% aluminum, 0.03-0.15% vanadium, 0.02-0.11% titanium, provided that the atomic percent of titanium is between 1 and 1.6 times the atomic percent of sulfur plus nitrogen, balance iron, said steel being characterized by a YS/TS ratio .ltoreq.0.6.
A method of producing a dual-phase steel possessing high strength, good ductility, and a YS/TS ratio .ltoreq.0.6, comprising the steps of preparing a chemically balanced ferrous alloy consisting essentially of the following, by weight:
Dependencies are inferred from the claim text.