Ultrahigh-strength multiphase steel with improved properties during production and processing

US10273552B2 · kind B2 · utility

Assignee

• Salzgitter Flachstahl GmbH · DE

Inventors

• Thomas Schulz · Austin, US
• Andreas Wedemeier · Braunschweig, DE
• Wilfried Sprock · Braunschweig, DE
• Volker Flaxa · Salzgitter, DE
• Friedrich Luther · Gehrden, DE
• Ingwer Denks · Duisburg, DE
• Sven Schulz · Lengede, DE

Key dates

• Filing date: Jan 15, 2013
• Grant date: Apr 30, 2019
• Expiry date: Jul 13, 2035

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

In a process for producing a cold- or hot-rolled steel strip from an ultrahigh-strength multiphase steel having a particular composition the required multiphase microstructure is generated during continuous heat treatment. The cold- or hot-rolled steel strip is heated in the continuous heat treatment furnace to a temperature in the range from 700 to 950° C. and the heat-treated steel strip is subsequently cooled from the heat treatment temperature at a cooling rate of from 15 to 100° C./s to a first intermediate temperature of from 300 to 500° C. followed by cooling at a cooling rate of from 15 to 100° C./s to a second intermediate temperature of from 200 to 250° C.; the steel strip is subsequently cooled at a cooling rate of from 2 to 30° C./s in air to room temperature or the cooling at a cooling rate of from 15 to 100° C./s is maintained from the first intermediate temperature to room temperature.