Patent ID: 11939643
Assignee: ARCELORMITTAL
Field: Surface technology, coating (Chemistry)
Classification: CPC C  B  Y | IPC B  C

Claim 0:
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.