Salzgitter Flachstahl Gmbh

Thomas Schulz

Andreas Wedemeier

Sascha Kluge

Joachim Schöttler

Friedrich Luther

Volker Flaxa

Ingwer Denks

Sebastian Westhäuser

Sven Schulz

Tobias Klinkberg

Thorsten Michaelis

Peter Matthies

Christian Meyer

Michael Pohl

Hans-Joachim Kratz

Matthias Geler

Oliver Meyer

Marion Calcagnotto

Wilfried Sprock

Marion Bechtold

Norbert Kwiaton

Alexander Georgiew

Jörg Heinecke

Christian Schlegel

Philipp WÜLLNER

A high-strength air-hardenable multiphase steel having minimal tensile strengths in a non air hardened state of 750 MPa and excellent processing properties, said steel comprising the following elements in % by weight: C&#x2265;0.075 to &#x2264;0.115; Si&#x2265;0.200 to &#x2264;0.300; Mn&#x2265;1.700 to &#x2264;2.300; Cr&#x2265;0.280 to &#x2264;0.4800; Al&#x2265;0.020 to &#x2264;0.060; N&#x2265;0.0020 to &#x2264;0.0120; S&#x2264;0.0050; Nb&#x2265;0.005 to &#x2264;0.050; Ti&#x2265;0.005 to &#x2264;0.050; B&#x2265;0.0005 to &#x2264;0.0060; Ca&#x2265;0.0005 to &#x2264;0.0060; Cu&#x2264;0.050; Ni&#x2264;0.050; remainder iron, including usual steel accompanying smelting related impurities, wherein for a widest possible process window during continuous annealing of hot rolled or cold rolled strips made from the steel a sum content of M+Si+Cr in the steel is a function of a thickness of the steel strips according to the following relationship: for strip thicknesses of up to 1.00 mm the sum content of M+Si+Cr is &#x2265;2.350 and &#x2264;2.500%, for strip thicknesses of over 1.00 to 2.00 mm the sum of Mn+Si+Cr is &#x2265;2.500 and &#x2264;2.950%, and for strip thicknesses of over 2.00 mm the sum of Mn+Si+Cr is &#x2265;2.950 and &#x2264;3.250%.

High-strength air-hardening multiphase steel having excellent processing properties, and method for manufacturing a strip of said steel

An ultra-high-strength air-hardenable multiphase steel having minimal tensile strengths in a non air hardened state of 950 MPa and excellent processing properties, includes the following elements in % by weight: C&#x2265;0.075 to &#x2264;0.115; Si&#x2265;0.400 to &#x2264;0.500; Mn&#x2265;1,900 to &#x2264;2,350; Cr&#x2265;0.200 to &#x2264;0.500; Al&#x2265;0.005 to &#x2264;0.060; N&#x2265;0.0020 to &#x2264;0.0120; S&#x2264;0.0030; Nb&#x2265;0.005 to &#x2264;0.060; Ti&#x2265;0.005 to &#x2264;0.060; B&#x2265;0.0005 to &#x2264;0.0030; Mo&#x2265;0.200 to &#x2264;0.300; Ca&#x2265;0.0005 to &#x2264;0.0060; Cu&#x2264;0.050; Ni&#x2264;0.050; remainder iron, including usual steel accompanying smelting related impurities, wherein for a widest possible process window during continuous annealing of hot rolled or cold rolled strips made from said steel a sum content of M+Si+Cr in said steel is a function of a thickness of the steel strips according to the following relationship: for strip thicknesses of up to 1.00 mm the sum content of M+Si+Cr is &#x2265;2.800 and &#x2264;3.000%, for strip thicknesses of over 1.00 to 2.00 mm the sum of Mn+Si+Cr is &#x2265;2.850 and &#x2264;3.100%, and for strip thicknesses of over 2.00 mm the sum of Mn+Si+Cr is &#x2265;2.900 and &#x2264;3.200%.

Ultra high-strength air-hardening multiphase steel having excellent processing properties, and method for manufacturing a strip of said steel

A high-strength multi-phase steel having minimum tensile strengths of 750 MPa and preferably having a dual-phase microstructure for a cold- or hot-rolled steel strip, in particular for lightweight vehicle construction is disclosed. The high-strength multi-phase steel has improved forming properties and a ratio of yield point to tensile strength of at most 73%. The high-strength multi-phase steel includes in mass %: C&#x2265;0.075 to &#x2264;0.105; Si&#x2265;0.600 to &#x2264;0.800; Mn&#x2265;1.000 to &#x2264;0.700; Cr&#x2265;0.100 to &#x2264;0.480; Al&#x2265;0.010 to &#x2264;0.060; N 0.0020&#x2264;0.0120; S&#x2264;0.0030; Nb&#x2265;0.005 to &#x2264;0.050; Ti&#x2265;0.0050 to &#x2264;0.050; B&#x2265;0.0005 to &#x2264;0.0040; Mo&#x2264;0.200; Cu&#x2264;0.040%; Ni&#x2264;0.040 % the remainder iron, including typical elements accompanying steel that are not mentioned above, which represent contamination resulting from smelting.

Micro-alloyed high-strength multi-phase steel containing silicon and having a minimum tensile strength of 750 MPA and improved properties and method for producing a strip from said steel

A high-strength multi-phase steel having tensile strengths of no less than 580 MPa, preferably with a dual-phase structure for a cold-rolled or hot-rolled steel strip having improved forming properties, in particular for lightweight vehicle construction is disclosed, containing the following elements (contents in % by mass): C 0.075 to &#x2264;0.105; Si 0.200 to &#x2264;0.300; Mn 1.000 to &#x2264;2.000; Cr 0.280 to &#x2264;0.480; Al 0.10 to &#x2264;0.060; P &#x2264;0.020; Nb &#x2265;0.005 to &#x2265;0.025; N &#x2265;0.0100; S &#x2265;0.0050; the remainder iron, including conventional steel-accompanying elements not mentioned above.

High strength multi-phase steel, and method for producing a strip from said steel

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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Salzgitter, Germany

Thomas Schulz