Steel sheet coated with a metallic coating based on aluminum
A steel sheet with a metallic coating is provided. A composition of the metallic coating includes from 2.0 to 24.0% by weight of zinc, from 7.1 to 12.0% by weight of silicon, optionally from 1.1 to 8.0% by weight of magnesium, and optionally additional elements chosen from Pb, Ni, Zr, or Hf. The content by weight of each additional element is less than 0.3%. A balance of the composition is aluminum, unavoidable impurities and residual elements. A ratio Al/Zn is from 4.0 to 6.0.
1. A part formed by hot-forming a steel sheet coated with a metallic coating,
the metallic coating comprising 2.0 to 24.0% by weight of zinc, 7.1 to 12.0% by weight of silicon, 0.0%<=Pb<0.3%, 0.0%<=Ni<0.3%, 0.0%<=Zr<0.3%, and 0.0%<=Hf<0.3%; a balance being aluminum, unavoidable impurities and residual elements, but not comprising In and not comprising Sn, with a weight ratio of Al/Zn being greater than 2.9; and
a microstructure of the part being mostly martensitic, martensito-bainitic or comprising at least 75% equiaxed ferrite, from 5 to 20% martensite and 10% or less bainite,
a coupling potential of the part being under −0.78V/SCE.
2. The part according to claim 1 , wherein the part is formed by hot-forming and cold-stamping.
3. The part according to claim 1 , wherein the part has a variable thickness.
4. The part according to claim 3 , wherein the variable thickness is produced by a continuous flexible rolling process.
5. The part according to claim 1 , wherein the formed part is a tailored rolled blank.
6. The part according to claim 1 , wherein the part is a front rail, a seat cross member, a side sill member, a dash panel cross member, a front floor reinforcement, a rear floor cross member, a rear rail, a B-pillar, a door ring or a shotgun.
7. The part according to claim 1 , wherein the part is martensito-bainitic.
8. The part according to claim 1 , wherein the part comprises at least 75% equiaxed ferrite, from 5 to 20% martensite and 10% or less bainite.
9. An automotive vehicle comprising:
the part according to claim 1 .
10. The part according to claim 1 , wherein the metallic coating also does not comprise Cr.
11. The part according to claim 1 , wherein the metallic coating also does not comprise Mn.
12. The part according to claim 1 , wherein the metallic coating also does not comprise Ti.
13. The part according to claim 1 , wherein the metallic coating also does not comprise any of the following elements: Cr, Mn, Ti, Ce, La, Nd, Pr, Ca, Bi and Sb.
14. The part according to claim 1 , wherein the metallic coating includes 1.1 to 8.0% by weight magnesium.
15. The part according to claim 1 , wherein the metallic coating includes at least one element chosen from Pb, Ni, Zr or Hf.