Salzgitter Flachstahl Gmbh

Christian Pelz

Ingwer Denks

Joachim Schöttler

Michael Braun

Stefan Mütze

Nils Köpper

Patrick Witteler

Maik Habermann

Stefan Mecke

Ansgar Geffert

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

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Wolfenbüttel, Germany

Christian Pelz