Salzgitter Flachstahl Gmbh

Ingwer Denks

Christian Pelz

Friedrich Luther

Joachim Schöttler

Michael Braun

Volker Flaxa

Thomas Schulz

Stefan Mütze

Andreas Wedemeier

Nils Köpper

Sven Schulz

Maik Habermann

Stefan Mecke

Wilfried Sprock

Ansgar Geffert

Patrick Witteler

Stefan MÜTZE

Joachim SCHÖTTLER

The invention relates to a method for producing a chassis part from micro-alloyed steel, having an improved cold workability of cold-solidified, mechanically separated sheet-metal edges, comprising the following method steps: —providing a hot-rolled strip or a hot-rolled strip sheet of the claimed alloy composition in weight percent, cutting a blank at room temperature and optionally carrying out further punching or cutting operations, —heating exclusively the sheet metal edge regions of the blank, which have been cold-solidified by the cutting or punching operations, to a temperature of at least 700° C. with a dwell time of at most 10 seconds and subsequent cooling with air, —cold forming the blank in one or more steps to form a chassis part at room temperature.

Method for the production of chassis parts from micro-alloyed steel with improved cold formability

A flat product of steel with yield strength Rp 0.2 of 660 to 820 MPa, BH2 value greater than 30 MPa, a hole expansion ratio greater than 30%, and a microstructure having a first main component at a proportion of at least 50%, including one or more individual components of ferrite, tempered bainite, and tempered martensite, each with less than 5% carbides, and a second main component at a proportion of 5% to 50%, including one or more individual components of martensite, residual austenite, bainite or perlite, with the steel having a following chemical composition (in weight %): C: 0.04 to 0.12; Si: 0.03 to 0.8; Mn: 1 to 2.5: P: max. 0.08; S: max. 0.01; N: max. 0.01; Al: up to 0.1; Ni+Mo; up to 0.5; Nb: up to 0.08; Ti: up to 0.2; Nb+Ti: min, 0.03; Cr: up to 0.6; the remainder being iron including unavoidable steel-associated elements.

High-strength, hot-rolled flat steel product with high edge cracking resistance and, at the same time, high bake-hardening potential, and method for producing such a flat steel product

The invention relates to a method for producing a hot-rolled strip composed of a bainitic multi-phase steel and having a Zn&#x2014;Mg&#x2014;Al coating, comprising the following steps: melting a steel melt containing (in weight percent): C: 0.04-0.11, Si: &#x3c;=0.7, Mn: 1.4-2.2, Mo: 0.05-0.5, Al: 0.015-0.1, P: up to 0.02, S: up to 0.01, B: up to 0.006, and at least one element from the group Nb, V, Ti in accordance with the following condition: 0.02&#x3c;=Nb+V+Ti&#x3c;=0.20, the remainder being iron including unavoidable steel-accompanying elements resulting from the melting process, casting the steel melt into a preliminary material, in particular a slab or a block or a thin slab, hot rolling the preliminary material into a hot-rolled strip having a final rolling temperature in the range of 800 to 950&#xb0; C., cooling the hot-rolled strip to a winding temperature less than 650&#xb0; C., winding the hot-rolled strip at a winding temperature less than 650&#xb0; C., cooling the wound hot-rolled strip to room temperature in still air, wherein the microstructure of the wound hot-rolled strip then has a bainite fraction greater than 50% after the hot rolling, heating the hot-rolled strip to a temperature greater than 650&#xb0; C. and less than Ac3, in particular less than Ac1+50&#xb0; C., cooling the hot-rolled strip to zinc bath temperature, hot-dip coating the heated hot-rolled strip in a zinc alloy molten bath containing (in weight percent): Al: 1.0-2.0, Mg: 1.0-2.0, the remainder being zinc and unavoidable impurities. The invention further relates to the hot-rolled strip produced in accordance with the method above and to shaped, dynamically highly loadable components, in particular motor vehicle parts, that are produced from said hot-roiled strip and that are resistant to corrosive and abrasive influences.

Method for producing a hot strip of a bainitic multi-phase steel having a Zn&#x2014;Mg&#x2014;Al coating, and a corresponding hot strip

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

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Wolfenbüttel, Germany

Ingwer Denks