Pre-oxidized, coating-free press hardened steel
AssigneeGM Global Technology Operations LLC
InventorsZhou Wang, Zhao Li, MingFeng Shi, Sarah Tedesco, Jianfeng Wang, Jiachen Pang, Zhen Chen
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Abstract
A pre-oxidized steel sheet for press hardening, a press hardened, pre-oxidized steel sheet for a vehicle component, and a method of forming a pre-oxidized steel sheet. The pre-oxidized steel sheet includes a surface, a bulk region beneath the surface, and an oxide layer disposed on the surface. The oxide layer exhibits a thickness in the range of 20 nanometers to 60 nanometers and includes at least one of a manganese oxide, an iron oxide, a manganese iron oxide, a chromium oxide, and an amorphous silicon oxide.
Claims6
A pre-oxidized steel sheet for press hardening, comprising:
- a surface;
- a bulk region beneath the surface, the bulk region comprising a steel composition including
- carbon (C) present in the range of 0.05 weight percent to 0.35 weight percent of the total weight percent of the composition,
- manganese (Mn) present in the range of 0.5 weight percent to 5.0 weight percent of the total weight percent of the composition,
- silicon (Si) present in the range of 0.5 weight percent to 2.0 weight percent of the total weight percent of the composition,
- chromium (Cr) present in the range of 0.6 weight percent to 4.0 weight percent of the total weight percent of the composition,
- optionally niobium (Nb) present in the range of 0.02 weight percent to 0.05 weight percent of the total weight percent of the composition, and
- iron present in the remainder of the composition to provide a total weight percent of 100 percent;
- an oxide layer disposed on the surface, the oxide layer comprising at least one of a manganese oxide, an iron oxide, a manganese iron oxide, a chromium oxide, and an amorphous silicon oxide, the oxide layer exhibiting a thickness in the range of 20 nanometers to 60 nanometers;
- and
- a subsurface depletion zone between the bulk region and the surface, wherein the subsurface depletion zone exhibits a thickness of less than 0.7 micrometers and includes manganese present in the range of 25 percent to 50 percent of the amount of manganese in the bulk region.
A press hardened, pre-oxidized steel sheet for a vehicle component, comprising:
- a surface;
- a bulk region beneath the surface, the bulk region comprising a steel composition including
- carbon (C) present in the range of 0.05 weight percent to 0.35 weight percent of the total weight percent of the composition,
- manganese (Mn) present in the range of 0.5 weight percent to 5.0 weight percent of the total weight percent of the composition,
- silicon (Si) present in the range of 0.5 weight percent to 2.0 weight percent of the total weight percent of the composition,
- chromium (Cr) present in the range of 0.6 weight percent to 4.0 weight percent of the total weight percent of the composition,
- optionally niobium (Nb) present in the range of 0.02 weight percent to 0.05 weight percent of the total weight percent of the composition, and
- iron present in the remainder of the composition to provide a total weight percent of 100 percent;
- and
- an oxide layer disposed on the surface, the oxide layer comprising at least one of a manganese oxide, an iron oxide, a manganese iron oxide, a chromium oxide, and an amorphous silicon oxide, the oxide layer exhibiting a thickness in the range of 60 nanometers to 1 micrometer,
- wherein the bulk region exhibits a martensitic structure present in the range of 85 to 99.8 percent by volume of the total volume of the bulk region with austenite present in the range of 0.1 to 8 percent by volume of the total volume of the bulk region and carbide phases present in the range of 0.1 to 7 percent by volume of the total volume of the bulk region, wherein the total volume of the bulk region is 100 percent.
Dependencies are inferred from the claim text.