Abstract:
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 (Vc) between 4° and 12° C./s, wherein Vc is 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.
Abstract:
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.
providing at least one second steel sheet with a composition containing, by weight, from to 0.38% of carbon, the at least one second steel sheet precoated with a metallic precoating of aluminum, or aluminum-based alloy, or aluminum alloy; removing a portion of a thickness of the aluminum precoating at upper and lower sides along one side of a periphery of the at least one first steel sheet and the at least one second steel sheet; creating a welded blank by laser welding the at least one first steel sheet and the at least one second steel sheet, such that an aluminum content in a weld metal is lower than 0.3% by weight, the laser welding being performed along the periphery wherein the portion of the thickness of the aluminum precoating has been removed; heating the welded blank and holding the welded blank at a temperature Tm between 890 and 950° C., a holding duration Dm at the temperature being between 1 and 10 minutes, so as to obtain a heated welded blank; transferring the heated welded blank within a forming press, the transfer duration Dt being less than 10 s; hot forming the heated welded blank in the forming press so as to obtain a welded formed part; and cooling the welded formed part at a first cooling rate CR1 between 40 and 360° C./s in a temperature range between 750 and 450° C., and at a second cooling rate CR2 between 15 to 150° C./s in a temperature range between 450° C. and 250° C., wherein CR2
Abstract:
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 tp of 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.
Abstract:
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 tp of 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.
Abstract:
This invention relates to a cold-rolled sheet that is annealed and pre-coated for the fabrication of press hardened parts, composed of a steel substrate for heat treatment with a carbon content C0 between 0.07% and 0.5%, whereby this content is expressed by weight, and a metal pre-coating on at least the two principal faces of the steel substrate, characterized in that the substrate comprises a decarburized area on the surface of each of the two principal faces, whereby the depth p50% of the decarburized area is between 6 and 30 micrometers, whereby p50% is the depth at which the carbon content is equal to 50% of the content C0, and in that the sheet does not contain a layer of iron oxide between the substrate and the metal pre-coating.
Abstract:
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 tp of 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.
Abstract:
A press hardened steel part is provided. The steel of the part has a chemical composition including, in weight: 0.062%≤C≤0.095%, 1.4%≤Mn≤1.9%, 0.2%≤Si≤0.5%, 0.020%≤Al≤0.070%, 0.02%≤Cr≤0.1%, wherein: 1.5%≤(C+Mn+Si+Cr)≤2.7%, 0.040%≤Nb≤0.060%, 3.4×N≤Ti≤8×N wherein: 0.044%≤(Nb+Ti)≤0.090%, 0.0005≤B≤0.004%, 0.001%≤N≤0.009%, 0.0005%≤S≤0.003%, 0.001%≤P≤0.020%, optionally: 0.0001%≤Ca≤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.
Abstract:
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 −30 and +30° 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. %.
Abstract:
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%≤C≤0.095%, 1.4%≤Mn≤1.9%, 0.2%≤Si≤0.5%, 0.020%≤Al≤0.070%, 0.02%≤Cr≤0.1%, wherein: 1.5%≤(C+Mn+Si+Cr)≤2.7%, 0.040%≤Nb≤0.060%, 3.4×N≤Ti≤8×N wherein: 0.044%≤(Nb+Ti)≤0.090%, 0.0005≤B≤0.004%, 0.001%≤N≤0.009%, 0.0005%≤S≤0.003%, 0.001%≤P≤0.020%, optionally: 0.0001%≤Ca≤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°C/s in a temperature range from 750 to 450°C. and at a cooling rate CR2 between 15 to 150°C/s in a temperature range from 450°C to 250°C. wherein CR2
Abstract:
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 tp of 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.