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US 11,530,469 B2Granted
Press hardened steel with surface layered homogenous oxide after hot forming
AssigneeGM Global Technology Operations LLC
InventorsQi Lu, Jianfeng Wang
Life of this patent
Estimating the term…
Abstract
A press-hardened steel is provided. The press-hardened steel has an alloy matrix including from about 0.01 wt. % to about 0.35 wt. % carbon, from about 1 wt. % to about 9 wt. % chromium, from about 0.5 wt. % to about 2 wt. % silicon, and a balance of iron. The alloy matrix is greater than or equal to about 95 vol. % martensite. A first layer is disposed directly on the alloy matrix. The first layer is continuous, has a thickness of greater than or equal to about 0.01 μm to less than or equal to about 10 μm, and includes an oxide enriched with chromium and silicon. A second layer is disposed directly on the first layer, and includes an oxide enriched with Fe. Methods of preparing the press-hardened steel are also provided.
Claims17
A press-hardened steel comprising:
- an alloy matrix comprising:
- carbon (C) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.35 wt. %,
- chromium (Cr) at a concentration of greater than or equal to about 2.2 wt. % to less than or equal to about 9 wt. %,
- silicon (Si) at a concentration of greater than or equal to about 1.1 wt. % to less than or equal to about 2 wt. %, and
- a balance of iron (Fe), the alloy matrix being greater than or equal to about 95 vol. % martensite;
- a first layer disposed directly on the alloy matrix, the first layer being continuous, having a first thickness of greater than or equal to about 0.01 micrometer to less than or equal to about 10 micrometers, and comprising an oxide enriched with Cr and Si;
- and
- a second layer disposed directly on the first layer, the second layer being continuous, having a second thickness of greater than or equal to about 0.01 micrometers to less than or equal to about 30 micrometers, and comprising an oxide enriched with Fe.
5 more elements
A press-hardened steel comprising:
- an alloy matrix comprising:
- carbon (C) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.35 wt. %,
- chromium (Cr) at a concentration of greater than or equal to about 2.2 wt. % to less than or equal to about 9 wt. %,
- silicon (Si) at a concentration of greater than or equal to about 1.1 wt. % to less than or equal to about 2 wt. %, and
- a balance of iron (Fe), the alloy matrix being greater than or equal to about 95 vol. % martensite;
- a first layer disposed directly on the alloy matrix, the first layer being continuous, having a first thickness of greater than or equal to about 0.01 micrometer to less than or equal to about 10 micrometers, and comprising an oxide enriched with Cr and Si;
- and
- a second layer disposed directly on the first layer, the second layer being continuous and homogenous, having a second thickness greater than or equal to about 0.01 micrometer to less than or equal to about 30 micrometers, and comprising FeO, Fe2O3, Fe3O4, or a combination thereof,
- wherein the first layer and the second layer are derived from the alloy matrix during press hardening, and
- wherein the press-hardened steel is free of any layer or coating not having an element derived from the alloy matrix.
7 more elements
A method of fabricating a press-hardened steel component, the method comprising:
- cutting a blank from a steel alloy, the steel alloy being uncoated and comprising:
- carbon (C) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.35 wt. %,
- chromium (Cr) at a concentration of greater than or equal to about 2.2 wt. % to less than or equal to about 9 wt. %,
- silicon (Si) at a concentration of greater than or equal to about 1.1 wt. % to less than or equal to about 2 wt. %, and
- a balance of iron (Fe);
- heating the blank to a temperature greater than or equal to about 880° C. to less than or equal to about 950° C. to fully austenitize the steel alloy;
- stamping the blank in a die to form a structure having a predetermined shape from the blank;
- and
- quenching the structure to a temperature less than or equal to about a martensite finish (Mf) temperature of the steel alloy and greater than or equal to about room temperature to form the press-hardened steel component,
- wherein the press-hardened steel component comprises:
- an alloy matrix including the C, Cr, Si, and Fe of the steel alloy;
- a first layer disposed directly on the alloy matrix, the first layer being continuous, having a first thickness of greater than or equal to about 0.01 micrometer to less than or equal to about 10 micrometers, and comprising an oxide enriched with portions of the Cr and of the Si of the steel alloy;
- and
- a second layer disposed directly on the first layer, the second layer being continuous and homogenous, having a second thickness of greater than or equal to about 0.01 micrometer μm to less than or equal to about 30 micrometers, and comprising an oxide enriched with a portion of the Fe of the steel alloy,
- wherein the method is free of a descaling step, and
- wherein the press-hardened steel component is free of a layer of zinc (Zn) or an aluminum-silicon (Al—Si) coating.
13 more elements
Dependencies are inferred from the claim text.