Thyssenkrupp Steel Europe Ag

Thyssen Krupp Ag

Jfe Steel Corporation

Evonik Operations Gmbh

Richard Georg Thiessen

Thomas Heller

Rainer Fechte-Heinen

Manuela Irnich

Shinjiro Kaneko

Jens-Ulrik Becker

Brigitte Hammer

Rudolf Schoenenberg

Sabine Zeizinger

Fusae Shiimori

Clemens Latuske

Karsten Machalitza

Jian Bian

Patrick Kuhn

Roland Sebald

Nina Kolbe

Frank Hisker

Thomas Rieger

Oliver Bulters

Rudolf Schönenberg

Jens Horstmann

Miriam Lange

Bernd Linke

Jan-Hendrik Rudolph

Almir Dzafic

Nicholas Winzer

Oliver Bülters

The present invention relates to a flat steel product which has good deep-drawing ability, low edge-crack sensitivity and good bending behaviour. To this end, the flat steel product contains a steel which consists of (in wt %) 0.1-0.5% C, 1.0-3.0% Mn, 0.9-1.5% Si, up to 1.5% Al, up to 0.008% N, up to 0.020% P, up to 0.005% S, 0.01-1% Cr and optionally one or more of the following elements: up to 0.2% Mo, up to 0.01% B, up to 0.5% Cu, up to 0.5% Ni and optionally a total of 0.005-0.2% microalloying elements, the remainder being iron and unavoidable impurities, wherein 75&#x3c;(Mn2+55*Cr)/Cr&#x3c;3000 where Mn is the Mn content of the steel in wt % and Cr is the Cr content of the steel in wt %. The steel has a structure which consists of at least 80 area % martensite, of which at least 75 area % is tempered martensite and at most 25 area % is non-tempered martensite, at least 5 volume % residual austenite, 0.5 to 10 area % ferrite and at most 5 area % bainite, wherein in the region of the phase boundary between tempered martensite and residual austenite there is a low-Mn ferrite seam which has a width of at least 4 nm and at most 12 nm and the Mn content of which is at most 50% of the average Mn content of the flat steel product. The flat steel product contains carbides with a length of less than or equal to 250 nm. The invention also relates to a method for producing a flat steel product according to the invention, in which method the structural characteristics of the flat steel product according to the invention are set by suitable heat treatment.

Flat steel product and method for producing same

The invention relates to the use of a Q&P steel for production of a formed component (2) for high-wear applications, wherein the Q&P steel has a hardness of at least 230 HB, especially at least 300 HB, preferably at least 370 HB, and a bending angle &#x3b1; of at least 60&#xb0;, especially at least 75&#xb0;, preferably at least 85&#xb0;, determined to VDA238-100, and/or a bending ratio of r/t&#x3c;2.5, especially r/t&#x3c;2.0, preferably r/t&#x3c;1.5, where t corresponds to the material thickness of the steel and r to the (inner) bending radius of the steel.

Use of a Q and P steel for producing a shaped component for high-wear applications

A hot-rolled flat steel product including (in wt %) C: 0.1-0.3%, Mn: 1.5-3.0%, Si: 0.5-1.8%, Al: &#x2264;1.5%, P: &#x2264;0.1%, S: &#x2264;0.03%, N: &#x2264;0.008%, optionally one or more of Cr: 0.1-0.3%, Mo: 0.05-0.25%, Ni: 0.05-2.0%, Nb: 0.01-0.06%, Ti: 0.02-0.07%, V: 0.1-0.3%, and B: 0.0008-0.0020%, the balance being iron and unavoidable impurities. This flat steel product possesses a tensile strength of 800-1500 MPa, a yield strength of &#x3e;700 MPa, an elongation at break of 7-25%, and a hole expansion of more than 20%. The structure is at least 85 area % martensite, of which at least half is tempered martensite, with the remainder being &#x2264;15 vol % residual austenite, &#x2264;15 area % bainite, &#x2264;15 area % polygonal ferrite, &#x2264;5 area % cementite and/or &#x2264;5 area % nonpolygonal ferrite, and has a kernel average misorientation of at least 1.50&#xb0;. Also, a method for producing the flat steel product, wherein the microstructure of the flat steel product is set by the heat treatment.

Hot-rolled flat steel product and method for the production thereof

A method for producing a cold-rolled steel strip with a yield ratio Re/Rm of at least 0.7, the cold-rolled steel product including iron, unavoidable impurities and (in wt. %) C: 0.05-0.20%, Si: 0.25-1.00%, Mn: 1.0-3.0%, Al: 0.02-1.5%, Cr: 0.1-1.5%, N: &#x3c;0.02%, P: &#x3c;0.03%, S: &#x3c;0.05% and optionally one or more of Ti, Mo, Nb, V, and B, Ti: up to 0.15%, Mo: &#x3c;2%, Nb: &#x3c;0.1%, V: &#x3c;0.12%, and B: 0.0005-0.003%. The cold-rolled flat steel product undergoes heat treatment for 4.5-24 hours at a temperature of 150-400&#xb0; C. Also, a cold rolled flat steel product discussed above having a structure including at least two phases, selected from (in vol. %) at least 10% tempered martensite, &#x3c;10% bainite, &#x3c;10% residual austenite and remainder ferrite, a yield ratio of at least 0.7, a tensile strength of &#x2265;750 MPa and a hole expansion of at least 18%.

Method for producing a cold-rolled flat steel product with high yield strength and flat cold-rolled steel product

A flat steel product having a tensile strength of at least 1200 MPa and consists of steel containing (wt %) C: 0.10-0.50%, Si: 0.1-2.5%, Mn: 1.0-3.5%, Al: up to 2.5%, P: up to 0.020%, S: up to 0.003%, N: up to 0.02%, and optionally one or more of the elements 'Cr, Mo, V, Ti, Nb, B and Ca' in the quantities: Cr: 0.1-0.5%, Mo: 0.1-0.3%, V: 0.01-0.1%, Ti: 0.001-0.15%, Nb: 0.02-0.05%, wherein &#x3a3;(V, Ti, Nb)&#x2266;0.2% for the sum of the quantities of V, Ti and Nb, B: 0.0005-0.005%, and Ca: up to 0.01% in addition to Fe and unavoidable impurities. The flat steel product has a microstructure with (in surface percent) less than 5% ferrite, less than 10% bainite, 5-70% untempered martensite, 5-30% residual austenite, and 25-80% tempered martensite, at least 99% of the iron carbide contained in the tempered martensite having a size of less than 500 nm.

High-strength flat steel product and method for producing same

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Malden, Netherlands

Richard Georg Thiessen