Salzgitter Flachstahl Gmbh

Salzgitter Ag

Max-planck-institut Fur Eisenforschung Gmbh

Volker Flaxa

Karl-Heinz Spitzer

Joachim Kroos

Hellfried Eichholz

Georg Frommeyer

Friedrich Luther

Thomas Evertz

Joachim Schöttler

Michael Braun

Rune Schmidt-Jürgensen

Thomas Schulz

Andreas Wedemeier

Markus Schäperkötter

Ingwer Denks

Klaus Freier

Birgit Reichert

Sven Schulz

Udo Brüx

Klaus Brockmeier

Wilfried Sprock

Klaus Brokmeier

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&#xb0; C. and the heat-treated steel strip is subsequently cooled from the heat treatment temperature at a cooling rate of from 15 to 100&#xb0; C./s to a first intermediate temperature of from 300 to 500&#xb0; C. followed by cooling at a cooling rate of from 15 to 100&#xb0; C./s to a second intermediate temperature of from 200 to 250&#xb0; C.; the steel strip is subsequently cooled at a cooling rate of from 2 to 30&#xb0; C./s in air to room temperature or the cooling at a cooling rate of from 15 to 100&#xb0; C./s is maintained from the first intermediate temperature to room temperature.

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

In a method for producing a hot strip of steel with material properties that are adjustable over the strip cross-section, a steel melt is fed onto a revolving casting belt of a horizontal strip casting facility and solidifies to form a pre-strip having a thickness between 6 and 20 mm, and the pre-strip is subjected to a hot rolling process after complete solidification. A gas jet or plasma jet composed of metallic and/or non-metallic elements that affect the material properties of the hot strip influences the steel melt that is still liquid and/or just about to start to solidify. The concentration of the elements introduced into the melt by the gas jet or plasma jet and diffusing into the melt is adjusted across the strip thickness and strip width by changing the influencing kinetic energy of the gas jet or plasma jet, the partial gas pressure and/or the applied temperature.

Method for producing a hot strip by means of strip casting with material properties adjustable across the strip cross-section

In a method for producing a component by hot forming of a pre-product made of steel, the pre-product is heated to forming temperature and subsequently formed. The product is heated to a temperature below the AC-transformation temperature and undergoes a strength increase prior to the heating by cold forming.

Method for producing a component by hot forming a pre-product made of steel

In a method for making hot strips, a workable lightweight construction steel is used which in particular can easily be deep-drawn cold and includes the main elements Si, Al and Mn, with high tensile strength and good TRIP and/or TWIP characteristics. The mass % are as follows for C 0.04 to &#x3c;1.0, Al 0.05 to &#x3c;4.0, SI 0.05 to &#x2266;6.0; Mn 9.0 to &#x2266;30.0, the remainder being iron with the common incidental steel elements. The melt is cast in a horizontal strip casting unit, close to the final dimensions at calm flow and without bending to form a pre-strip in the range between 6 and 15 mm, and subsequently is fed for further processing.

Method for making hot strips of lightweight construction steel

The production of a cold-rolled strip or sheet of steel with good deforming properties, which is subjected to recrystallizing annealing and, if appropriate, a dressing operation after hot rolling, coiling and cold rolling and has a bake-hardening potential after a subsequent deformation and for a subsequent temperature treatment, succeeds because the recrystallizing annealing is carried out in a bell-type furnace while coiled and because the strip or sheet is subjected to cooling at a cooling rate of &gE;1&deg; C./s after the recrystallizing annealing from a temperature T of 200&deg; C.&lE;T&lE;A . It is consequently possible to obtain properties of bell-annealed steels and nevertheless attain a bake-hardening effect, in particular for C contents of &gE;0.02%.

Process for producing a cold-rolled strip or sheet of steel and strip or sheet which can be produced by the process

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Salzgitter, Germany

Volker Flaxa