ULTRAHIGH-STRENGTH MULTIPHASE STEEL WITH IMPROVED PROPERTIES DURING PRODUCTION AND PROCESSING
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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.
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1-12. -12. (canceled)
- 13. A method for producing a cold or hot rolled steel strip from an ultrahigh-strength multiphase steel having combined properties in which the required multiphase microstructure is generated during a continuous annealing, in particular for the vehicle lightweight construction, said ultrahigh-strength multiphase comprising the elements (contents in weight %)
Specification