Arcelormittal

Arcelormittal France

Arcelormittal Investigacion Y Desarrollo, S.l.

Arcelor France

Audi Ag

Volkswagen Ag

Pascal Drillet

Dominique Spehner

Ronald Kefferstein

Raisa Grigorieva

Thierry Sturel

Florin Duminica

Brahim Nabi

Maria Poirier

Sujay Sarkar

Jonas Staudte

Juan David Puerta Velasquez

Daniel Bouleau

Damien Ormston

Uwe Paar

Alexandre Blaise

Ludwig Schaller

Michael Alsmann

Karl Michael Bader

Thomas Vietoris

Cédric Georges

Isabelle Thirion

Cedric Georges

A hot stamped coated steel product, the hot stamped coated steel product comprising: a base steel; and a coating having a thickness of including, proceeding from the base steel outwards: (a) an interdiffusion layer, (b) an intermediate layer, (c) an intermetallic layer, and (d) a superficial layer, the base steel having a composition comprising: 0.15%<carbon<0.5%; 0.5%<manganese<3%; 0.1%<silicon<0.5%; 0.01%<chromium<1%; titanium<0.2%; aluminum<0.1%; phosphorus<0.1%; sulfur<0.05%; 0.0005%<boron<0.08%; a weight ratio of titanium content with respect to the nitrogen content being in excess of 3.42; a remainder being iron and impurities inherent in processing.

Method of forming a hot stamped coated steel product

A press hardening method including the following steps: A. the provision of a steel sheet for heat treatment being optionally coated with a zinc- or aluminum-based pre-coating, B. the flexible rolling of the steel sheet in the rolling direction so as to obtain a steel sheet having a variable thickness, C. the cutting of the rolled steel sheet to obtain a tailored rolled blank, D. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, E. the heat treatment of the tailored rolled blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the tailored rolled blank into a press tool, G. the hot-forming of the tailored rolled blank to obtain a part having a variable thickness,H. the cooling of the part having a variable thickness obtained at step G).

Press hardening method

A process for manufacturing a press hardened laser welded steel part, includes providing at least one first steel sheet with a composition containing, by weight 0.062≤C≤0.095%, the at least one first steel sheet precoated with a metallic precoating of aluminum, or aluminum-based alloy, or aluminum alloy.

Process for manufacturing a press hardened laser welded steel part

A press hardening method includes the following steps: A. the provision of a steel sheet for heat treatment, precoated with a zinc- or aluminum-based pre-coating for anti-corrosion purpose, B. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, C. the batch annealing of the precoated steel sheet in an inert atmosphere to obtain a pre-alloyed steel sheet, D. the cutting of the pre-alloyed steel sheet to obtain blank, E. the thermal treatment of the blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the blank into a press tool, G. the hot-forming of the blank to obtain a part, H. the cooling of the part obtained at step G).

press hardening method includes the following steps: A. the provision of a steel sheet for heat-treatment, precoated with a zinc- or aluminum-based pre-coating, B. the deposition of a hydrogen barrier pre-coating over a thickness from 10 to 550 nm, and comprising at least one element chosen from among: nickel, chromium, magnesium, aluminum and yttrium, C. batch annealing of the precoated steel sheet to obtain a pre-alloyed steel sheet, the cooling after the batch annealing being performed at a speed of 29.0° C.hor less, D. the cutting of the pre-alloyed steel sheet to obtain blank, E. thermal treatment of the blank to obtain a fully austenitic microstructure in the steel, F. the transfer of the blank into a press tool, G. the hot-forming of the blank to obtain a part, H. the cooling of the part obtained at step G).

A process for manufacturing a non-stamped prealloyed steel coil, sheet or blank, comprising the following successive steps of: providing a non-stamped precoated steel coil, sheet or blank composed of a steel substrate covered by a precoating of aluminum, or aluminum-based alloy, or aluminum alloy, wherein the precoating thickness is comprised between 10 and 35 micrometers on each side of the steel coil, sheet or blank, then heating the non-stamped steel coil, sheet or blank in a furnace under an atmosphere containing at least 5% oxygen, up to a temperature θcomprised between 750 and 1000° C., for a duration tcomprised between tand t, wherein: t=23500/(θ−729.5) and t=4.946×10×θ, tdesignating the total duration in the furnace, θbeing expressed in ° C. and tand tbeing expressed in seconds, then cooling the non-stamped steel coil, sheet or blank at a cooling rate Vdown to a temperature θ, then maintaining the non-stamped steel coil, sheet or blank at a temperature θcomprised between 100 and 500° C., for a duration tcomprised between 3 and 45 minutes, so to obtain a diffusible hydrogen less than 0.35 ppm.

Manufacturing process of press hardened parts with high productivity

A method of forming a hot stamped coated steel product includes providing a precoated steel strip, the precoated steel strip including a base steel having a first side and a second side, and a precoating on at least one of the first side and the second side, the precoating being made of aluminum or an aluminum alloy; heating the precoated steel strip in a furnace, wherein the precoated strip experiences a temperature rise at a heating rate (V) between 4° and 12° C./s, wherein Vis a mean heating rate between 20 and 700 C; removing the heated precoated steel strip from the furnace; and then hot stamping the precoated strip to deform the precoated steel strip into a hot stamped coated steel product, the hot stamped coated steel product having a coating including, proceeding from the base steel outwards: (a) an interdiffusion layer, (b) an intermediate layer, (c) an intermetallic layer, and (d) a superficial layer.

A pre-coated steel strip is provided. The steel strip includes a strip of base steel having a length, a width, a first side, and a second side. The length of the strip is at least 100 m and the width is at least 600 mm. An aluminum or an aluminum alloy pre-coating is on at least part of at least one of the first or second sides of the strip of base steel. A thickness tof the pre-coating is from 20 to 33 micrometers at every location on at least one of the first or second sides. Processes, coated stamped products and land motor vehicles are also provided.

Coated steel strips, coated stamped products and methods

A press hardened steel part is provided. The steel of the part has a chemical composition including, in weight: 0.062%&#x2264;C&#x2264;0.095%, 1.4%&#x2264;Mn&#x2264;1.9%, 0.2%&#x2264;Si&#x2264;0.5%, 0.020%&#x2264;Al&#x2264;0.070%, 0.02%&#x2264;Cr&#x2264;0.1%, wherein: 1.5%&#x2264;(C+Mn+Si+Cr)&#x2264;2.7%, 0.040%&#x2264;Nb&#x2264;0.060%, 3.4&#xd7;N&#x2264;Ti&#x2264;8&#xd7;N wherein: 0.044%&#x2264;(Nb+Ti)&#x2264;0.090%, 0.0005&#x2264;B&#x2264;0.004%, 0.001%&#x2264;N&#x2264;0.009%, 0.0005%&#x2264;S&#x2264;0.003%, 0.001%&#x2264;P&#x2264;0.020%, optionally: 0.0001%&#x2264;Ca&#x2264;0.003%, and the remainder being Fe and unavoidable impurities. The microstructure of the part includes, in a majority of the part, in surface fractions: less than 40% of bainite, less than 5% of austenite, less than 5% of ferrite, and a remainder being martensite. The martensite is fresh martensite and self-tempered martensite.

Steel for press hardening and press hardened part manufactured from such steel

A press hardening method includes the following steps providing a carbon steel sheet coated with a barrier pre-coating including nickel and chromium wherein the weight ratio Ni/Cr is between 1.5 and 9, cutting the sheet to obtain a blank, thermal treatment of the blank in an atmosphere having an oxidizing power equal or higher than that of an atmosphere consisting of 1% by volume of oxygen and equal or smaller than that of an atmosphere consisting of 50% by volume of oxygen, such atmosphere having a dew point between &#x2212;30 and +30&#xb0; C., transfer of the blank into a press tool, hot-forming of the blank to obtain a part, cooling of the part to obtain a microstructure in steel being martensitic or martensito-bainitic or made of at least 75 wt. % of equiaxed ferrite, from 5 to 20 wt. % of martensite and bainite in amount less than or equal to 10 wt. %.

A process for manufacturing a press hardened steel part is provided. The steel of the part has a chemical composition including, in weight: 0.062%&#x2264;C&#x2264;0.095%, 1.4%&#x2264;Mn&#x2264;1.9%, 0.2%&#x2264;Si&#x2264;0.5%, 0.020%&#x2264;Al&#x2264;0.070%, 0.02%&#x2264;Cr&#x2264;0.1%, wherein: 1.5%&#x2264;(C+Mn+Si+Cr)&#x2264;2.7%, 0.040%&#x2264;Nb&#x2264;0.060%, 3.4&#xd7;N&#x2264;Ti&#x2264;8&#xd7;N wherein: 0.044%&#x2264;(Nb+Ti)&#x2264;0.090%, 0.0005&#x2264;B&#x2264;0.004%, 0.001%&#x2264;N&#x2264;0.009%, 0.0005%&#x2264;S&#x2264;0.003%, 0.001%&#x2264;P&#x2264;0.020%, optionally: 0.0001%&#x2264;Ca&#x2264;0.003%, and the remainder being Fe and unavoidable impurities. The process includes hot forming the heated blank in the forming press so as to obtain a formed part and cooling the formed part at a cooling rate CR1 between 40 and 360&#xb0;C/s in a temperature range from 750 to 450&#xb0;C. and at a cooling rate CR2 between 15 to 150&#xb0;C/s in a temperature range from 450&#xb0;C to 250&#xb0;C. wherein CR2&#x3c;CR1.

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Rozerieulles, France

Pascal Drillet