Line pipe steels and process of manufacturing

US9493864B2 · kind B2 · utility

Assignee

• AM/NS Calvert LLC · US

Inventors

• Bertram Wilhelm Ehrhardt · Mobile, US
• Chris John Paul Samuel · Mobile, US
• Ranbir Singh Jamwal · Mobile, US
• Gerald McGloin · Saraland, US
• Stanley Wayne Bevans · Decatur, US
• Markus Wilhelm Forsch · Mobile, US
• Rudolf Schonenberg · Hemer, DE

Key dates

• Filing date: Mar 14, 2014
• Grant date: Nov 15, 2016
• Expiry date: Nov 20, 2034

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/005
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process for producing high strength steel is provided. The process includes providing a steel slab having a chemical composition in weight percent within a range of 0.025-0.07 C, 1.20-1.70 Mn, 0.050-0.085 Nb, 0.022 max Ti, 0.065 max N, 0.0040 max S, 0.10-0.45 Si, 0.070 max P, with the balance being Fe and incidental impurities. The steel slab is soaked within a temperature range of 1150-1230° C., hot rolled using a roughing treatment in order to produce a transfer bar and further hot rolled using a finishing treatment in order to produce hot rolled strip. The hot rolled strip is cooled using a cooling rate between 10-100° C./second (sec) and coiled within a temperature range of 580-400° C. Finally, the coiled hot rolled strip has a yield strength of at least 80 ksi and a DWTT transition temperature equal or less than −20° C.