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US 8,307,680 B2Granted
Coated steel strips, methods of making the same, methods of using the same, stamping blanks prepared from the same, stamped products prepared from the same, and articles of manufacture which contain such a stamped product
AssigneeArcelorMittal France
InventorsPascal Drillet, Dominique Spehner, Ronald Kefferstein
Life of this patent
Estimating the term…
Abstract
Coated steel having a well defined and uniform thickness is useful and advantageous for preparing products by hot stamping. Products prepared by hot stamping such a steel are particularly advantageous when subjected to a subsequent spot welding step.
Claims6
A process for making a hot stamped coated steel sheet product, comprising:
- (A) heating an aluminum- or aluminum alloy pre-coated steel sheet in a furnace preheated to a temperature and during a time defined by trapezoid ABCD having heating time, temperature coordinates of about A (3 minutes, 930° C.), B (6 minutes, 930° C.), C (13 minutes, 880° C.), and D (4.5 minutes, 880° C.) if the thickness of said sheet is greater than or equal to 0.7 mm and less than or equal to 1.5 mm, and by trapezoid EFGH having heating time, temperature coordinates of about E (4 minutes, 940° C.), F (8 minutes, 940° C.), G (13 minutes, 900° C.), and H (6.5 minutes, 900° C.) if the thickness of said sheet is greater than 1.5 mm and less than or equal to 3 mm, at a heating rate Vc between 20 and 700° C. comprised between 4 and 12° C./s, to obtain a heated blank;
- (B) transferring said heated blank to a die;
- and
- (C) stamping said heated blank in said die, to thereby obtain a hot stamped steel sheet product, and
- wherein the said heated product is cooled at a mean rate of at least 50° C./s during an interval between when said product exits said furnace and when said product reaches 400° C.,
- wherein an elapsed time between when said heated blank exits said furnace and said stamping commences is not more than 10 seconds.
3 more elements
Dependencies are inferred from the claim text.