METHOD OF MAKING A PHOSPHATED PART FROM A SHEET CONTAINING AN ALUMINUM-BASED COATING AND A ZINC COATING Russian patent published in 2019 - IPC C23C2/12 C23C2/26 C23C2/40 C23C28/02 C23C14/16 C23C14/58 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to production of steel parts reinforced by press and made from sheets containing aluminum-based coating and zinc coating. Steel sheet for hardening under the press has an aluminum-based coating and contains a second zinc coating, the thickness of which is less than or equal to 1.1 mcm. Method of obtaining a part hardened under press, having a phosphating-suitable coating, comprises successive stages, at which said steel sheet is cut to produce a workpiece, which is then heated to temperature T1 from 840 to 950 °C to obtain a completely austenitic structure in steel, placed in a press and subjected to hot forming, and the obtained part hardened under the press is cooled to produce a martensite or martensite-bainitic structure in steel containing not less than 75 % equiaxed ferrite, martensite in an amount greater than or equal to 5 % and less than or equal to 20 %, and beinite in an amount less than or equal to 10 %.

EFFECT: parts have good characteristics in terms of phosphating and, therefore, good adhesion with paint.

22 cl, 5 dwg, 12 tbl