Molded sheet-metal part with improved hardness curve
AssigneeThyssenKrupp Steel Europe AG
InventorsSebastian STILLE, David HOFFMANN, Stefan BIENHOLZ, Christine BISCHOFF, Maria KÖYER
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Abstract
A shaped sheet metal part formed from a sheet steel blank includes a steel substrate which consists of a steel which includes 0.1-3% by weight of Mn and optionally up to 0.01% by weight of B. The shaped sheet metal part has an aluminum-based anticorrosion coating on at least one side and is characterized in that the magnitude of the hardness gradient of anticorrosion coating and steel substrate perpendicular to the surface of the steel substrate is less than 1.7 GPa/μm. A process for producing such a shaped sheet metal part.
Claims21
1-12. (canceled)
A process for producing a flat steel product for hot forming with a coating, comprising operating steps as follows:
- providing a slab or a thin slab comprising a steel which includes 0.1-3% by weight of Mn and optionally up to 0.01% by weight of B;
- through-heating the slab or thin slab at a temperature (T1) of 1000-1400° C.;
- hot rolling to give a hot-rolled flat steel product, where the final rolling temperature (T3) is 750-1000° C.;
- annealing the flat steel product at an annealing temperature (T5) of 650-900° C.;
- cooling the flat steel product to a dipping temperature (T6) of 600-800° C., preferably 680-720° C.;
- coating the flat steel product cooled to the dipping temperature with a coating by:
- immersing the product in a melt bath with a melt temperature (T7) of 660-800° C., preferably 670-710° C., where the melt bath comprises 0.5-4% by weight of Si, optionally 2-4% by weight of Fe, optionally up to 5.0% by weight of alkali metals or alkaline earth metals, optionally up to 10% by weight of Zn, and optional further constituents, the contents of which are limited to a total of not more than 2.0% by weight, and aluminum as the balance;
- and
- blowing off the flat steel product after discharge from the melt bath by means of a gas stream;
- and
- cooling the coated flat steel product to room temperature, where an average cooling rate between 660° C. and 570° C. is at least 15 K/s.
A shaped sheet metal part, comprising:
- a sheet metal blank comprising a steel substrate comprising a steel comprising 0.1-3% by weight of Mn and optionally up to 0.01% by weight of B, wherein the shaped sheet metal part on at least one side has an aluminum-based anticorrosion coating, characterized in that the magnitude of the hardness gradient of anticorrosion coating and steel substrate perpendicular to the surface of the steel substrate is less than 1.7 GPa/μm.
Dependencies are inferred from the claim text.