US 11,939,643 B2
Coated steel strips, coated stamped products and methods
Pascal Drillet, Rozerieulles (FR); Dominique Spehner, Balan (FR); and Ronald Kefferstein, Saint Mitre les Ramparts (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Filed by ArcelorMittal, Luxembourg (LU)
Filed on Sep. 20, 2021, as Appl. No. 17/479,050.
Application 17/479,050 is a division of application No. 17/319,306, filed on May 13, 2021, granted, now 11,326,227.
Application 13/621,015 is a division of application No. 12/447,777, granted, now 8,307,680, issued on Nov. 13, 2012, previously published as PCT/IB2006/004019, filed on Oct. 30, 2006.
Application 17/319,306 is a continuation of application No. 16/413,825, filed on May 16, 2019, granted, now 11,041,226, issued on Jun. 22, 2021.
Application 16/413,825 is a continuation of application No. 15/606,770, filed on May 26, 2017, granted, now 10,550,447, issued on Feb. 4, 2020.
Application 15/606,770 is a continuation of application No. 13/621,015, filed on Sep. 15, 2012, granted, now 9,708,683, issued on Jul. 18, 2017.
Prior Publication US 2022/0002834 A1, Jan. 6, 2022
Int. Cl. C21D 9/46 (2006.01); B32B 15/01 (2006.01); C23C 2/12 (2006.01); C23C 2/26 (2006.01); C23C 2/40 (2006.01)
CPC C21D 9/46 (2013.01) [B32B 15/012 (2013.01); C23C 2/12 (2013.01); C23C 2/26 (2013.01); C23C 2/40 (2013.01); Y10T 428/12389 (2015.01); Y10T 428/12396 (2015.01); Y10T 428/12757 (2015.01)] 29 Claims
OG exemplary drawing
 
1. A method of forming a hot stamped coated steel product, comprising:
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 for 3 to 13 minutes in a furnace pre-heated to between 880° C. and 940° C., 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 comprising, proceeding from the base steel outwards:
(a) an Interdiffusion layer,
(b) an Intermediate layer,
(c) an Intermetallic layer, and
(d) a Superficial layer,
wherein layers (a), (b), (c), and (d) each have a different mean composition from one another,
wherein the coating on the hot stamped coated steel product has a thickness greater than 30 micrometers;
wherein the interdiffusion layer has a first mean iron composition, the intermediate layer has a second mean iron composition less than the first mean iron composition; wherein the intermetallic layer has a third mean iron composition, the third mean iron composition less than the first mean iron composition and greater than the second mean iron composition, and the superficial layer has a fourth mean iron composition, the fourth mean iron composition being less than the third mean iron concentration.