Abstract: The present disclosure discloses a method for producing high strength hot rolled steel. The method includes casting a steel slab of a composition, comprising in weight %: carbon (C) of about 0.45 wt. %-1.2 wt. %, manganese (Mn) of about 0.0-1.0 wt. %, silicon (Si) of about 0.0-0.5 wt. %, niobium (Nb) up-to 0.03 wt. %, sulphur (S) up-to 0.05 wt. % of S, phosphorous (P) up-to 0.05 wt. %, nitrogen (N) 0.002 wt. %-0.012 wt. % and balance being Iron (Fe) optionally along with incidental elements. The method also involves, heating, hot rolling, cooling, coiling the steel and retaining the steel at an ambient temperature to produce high strength hot rolled steel with 75-95% spheroid microstructure and 5-25% pearlite microstructure.

Abstract: A process for making a hot rolled high strength steel (HRHSS) product including the steps of casting a steel slab having, in weight percent, C: 0.18-0.22, Mn: 1.0-2.0, Si: 0.8-1.2, Cr: 0.8-1.2, S: 0.008 max, P: 0.025 max, Al: 0.01-0.15, N: 0.005 max, Nb: 0.02-0.035, Mo: 0.08-0.12, the remainder iron (Fe) and incidental impurities, hot rolling the steel slab into strip at a finish rolling temperature (FRT) of 850-900° C., cooling the hot rolled strip at 40° C./s or more over a run out table (ROT) until the strip reaches 380-400° C., coiling the hot rolled strip, and then air cooling to room temperature.

Abstract: A process for producing dual phase steel sheet including steps of making a liquid steel having a chemical composition in wt % of C: 0.03-0.12. Mn: 0.8-1.5. Si: <0.1, Cr: 0.3-0.7, S: 0.008 maximum, P: 0.025 maximum, Al: 0.01 to 0.1, N: 0.007 maximum. Nb: 0.005-0.035. and V: 0.06 maximum, remainder Fe; continuous casting the liquid steel into a slab; hot rolling the slab into a hot rolled sheet at finish rolling temperature (FRT) 840±30 ° C.; cooling the hot rolled sheet on the run out table at a cooling rate 40 ?70° C./s to an intermediate temperature (Tint) of 720° C.?Tint?650° C.; natural cooling the hot rolled sheet for a duration of 5-7 seconds and rapidly cooling the hot rolled sheet to transform remaining carbon enriched austenite to martensite, at cooling rate of 40-70 ° C./s to a coiling temperature below 400° C.

Abstract: A process for making a hot rolled high strength steel (HRHSS) product including the steps of casting a steel slab having, in weight percent, C: 0.18-0.22, Mn: 1.0-2.0, Si: 0.8-1.2, Cr: 0.8-1.2, S: 0.008 max, P: 0.025 max, Al: 0.01-0.15, N: 0.005 max, Nb: 0.02-0.035, Mo: 0.08-0.12, the remainder iron (Fe) and incidental impurities, hot rolling the steel slab into strip at a finish rolling temperature (FRT) of 850-900° C., cooling the hot rolled strip at 40° C./s or more over a run out table (ROT) until the strip reaches 380-400° C., coiling the hot rolled strip, and then air cooling to room temperature.