Hot-stamped alloy, method for manufacturing hot-stamped part from such alloy, and part made of such alloy
By using alloys containing carbon, manganese, chromium, silicon and cerium for hot stamping, the problem of uneven oxide coating in the manufacturing of automotive structural parts is solved, and the formation of thin uniform oxide coating is achieved, and the spot welding quality and electrode life are improved.
Patent Information
- Application Number
- CN202311785026.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
Existing hot stamping alloys tend to form thick and uneven oxide coatings when manufacturing automotive structural parts, resulting in spot welding difficulties and shortening electrode life.
An alloy containing about 0.05-0.45% carbon, 0.5-4.5% manganese, 0.5-6% chromium, 0.5-2.5% silicon and 0.1-0.5% cerium were used to form a thin and uniform oxide coating by hot stamping.
It is achieved without the need for protective atmosphere, forming a thin and uniform oxide coating, improving the spot welding quality, extending the life of the spot welding electrode, and suppressing spot welding melting/ejection, making the resulting surface smoother.
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Figure CN120193205A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to alloys for hot stamping structural components such as automotive structural components, and to the hot stamping of such structural components, as well as to the resulting structural components themselves. Background Art
[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that the work currently attributed to the inventors is described in this section and aspects of the specification that may not otherwise be determined as prior art at the time of filing are not admitted, either expressly or impliedly, as prior art against the present disclosure.
[0003] A common method for manufacturing automotive structural components is hot stamping, also known as press hardening. However, using common alloys such as 22MnB5, hot stamping can result in severely oxidized components - components with thick and / or non-uniform oxide coatings, which require further processing such as sandblasting. To reduce the formation of these oxide coatings, hot stamping can be carried out in an inert atmosphere, but this complicates the manufacturing method and increases costs. Alternatively, a coating such as AlSi can be applied to the blank of the hot stamping component, but this also complicates the manufacturing method and increases costs.
[0004] Hot stamping alloys that are more resistant to oxide formation during the hot stamping process have been developed. An example of such an alloy has a nominal composition of 0.05 - 0.45 wt% C, 0 - 0.45 wt% Mn, 0.5 - 6 wt% Cr, 0.5 - 2.5 wt% Si, with the balance being iron. However, these alloys are difficult to spot weld during subsequent manufacturing processes because non-uniform surface oxides cause build-up on the spot welding electrodes, which shortens the electrode life and can result in welding artifacts on the surface. Summary of the Invention
[0005] Further applicable fields of the present disclosure will be apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended only to illustrate and are not intended to limit the scope of the present disclosure.
[0006] Embodiments of the present disclosure provide an improved metal alloy suitable for hot stamping. According to a first preferred embodiment, the alloy may comprise from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities.
[0007] The cerium content is preferably higher than about 0.1 wt% to improve the quality of the surface after hot stamping. The cerium content is preferably less than about 0.5 wt% to maintain steel casting and rolling quality. In some versions of this first embodiment, in order to more easily remove scale in a rolling mill, it may be desirable to keep the sum of the Cr and Si contents less than or equal to about 5 wt%. In some versions of this first embodiment, in order to provide high temperature oxidation resistance during hot stamping, it may be desirable to keep the ratio of Cr:Si in the range of about 1.25:1 to about 3:1.
[0008] The alloy does not need to be processed in a protective atmosphere such as nitrogen or argon, and the processing typically results in a thin, uniform oxide coating with a thickness less than 1 μm, typically less than 0.5 μm, and typically in the range of 0.1 to 0.2 μm. The thin, uniform oxide layer is less damaging to spot welding tips compared to the thicker and / or more non-uniform oxide coatings formed on existing hot stamping alloys.
[0009] According to a second preferred embodiment of the present disclosure, a method of manufacturing a structural component, such as an automotive structural component, is disclosed. The method according to this second preferred embodiment includes heating a metal alloy blank comprising from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities.
[0010] The heated metal blank is then hot stamped into the desired structural component. This composition provides a wider processing window in terms of both temperature and duration. For example, in one version, the heating occurs in a space defined by the time-temperature points (300 s, 870 °C), (200 s, 980 °C), (800 s, 870 °C), and (1000 s, 980 °C). In another version, the heating occurs in a space defined by the time-temperature points (300 s, 870 °C), (200 s, 980 °C), (1000 s, 870 °C), and (800 s, 980 °C). In some cases, the heating can be carried out in an inert atmosphere, such as a nitrogen or argon atmosphere, but this is generally not necessary.
[0011] According to a third preferred embodiment of the present disclosure, it provides a structural component. According to the third embodiment, the structural component, such as an automotive structural component, is made of about 0.05 to about 0.45 wt% carbon; about 0.5 to about 4.5 wt% manganese; about 0.5 to about 6 wt% chromium; about 0.5 to about 2.5 wt% silicon, about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities, and is formed by hot stamping, which has a substantially uniform oxidation thickness of less than about 0.5 μm after hot stamping. For example, the component can be an automotive pillar, a door beam, and a bumper beam.
[0012] Hot stamping products with such alloy blanks can obtain components with a thin and uniform oxide coating, without the need for sandblasting or other processing steps. The thin, substantially uniform oxide coating improves spot welding, extends the life of spot welding electrodes, and inhibits spot welding melting / ejection, thereby producing a smoother surface.
[0013] The present disclosure relates to the following solutions:
[0014] Solution 1. A metal alloy suitable for hot stamping, the alloy comprising about 0.05 to about 0.45 wt% carbon; about 0.5 to about 4.5 wt% manganese; about 0.5 to about 6 wt% chromium; about 0.5 to about 2.5 wt% silicon, about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities.
[0015] Solution 2. The metal alloy according to Solution 1, wherein the sum of the Cr and Si contents is less than or equal to about 5 wt%.
[0016] Solution 3. The metal alloy according to Solution 2, wherein the ratio of Cr:Si is about 1.25 to about 3.
[0017] Solution 4. The metal alloy according to Solution 1, wherein the ratio of Cr:Si is about 1.25 to about 3.
[0018] Solution 5. A method of manufacturing an automotive structural component, which includes:
[0019] heating a metal alloy blank, the metal alloy blank comprising about 0.05 to about 0.45 wt% carbon; about 0.5 to about 4.5 wt% manganese; about 0.5 to about 6 wt% chromium; about 0.5 to about 2.5 wt% silicon, about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities; and
[0020] hot stamping the blank into a desired automotive structural component.
[0021] Solution 6. The method according to Solution 5, wherein the heating occurs in a space defined by time and temperature points (300 s, 870 °C), (200 s, 980 °C), (800 s, 870 °C), and (1000 s, 980 °C).
[0022] Solution 7. The method according to Solution 5, wherein the heating occurs in a space defined by time and temperature points (300 s, 870 °C), (200 s, 980 °C), (1000 s, 870 °C), and (800 s, 980 °C).
[0023] Solution 8. The method according to Solution 5, which further includes that the heating is carried out in an inert atmosphere.
[0024] Solution 9. The method according to Solution 5, wherein the combined billets have a total Cr and Si content of less than or equal to about 5 wt%.
[0025] Solution 10. The method according to Solution 9, wherein the combined billets have a Cr:Si ratio of about 1.25 to about 3.
[0026] Solution 11. The method according to Solution 5, wherein the Cr:Si ratio is about 1.25 to about 3.
[0027] Solution 12. An automotive structural component made of about 0.05 to about 0.45 wt% carbon; about 0.5 to about 4.5 wt% manganese; about 0.5 to about 6 wt% chromium; about 0.5 to about 2.5 wt% silicon, about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities, formed by hot stamping, and having a uniform oxidation thickness of 0.5 μm after hot stamping.
[0028] Solution 13. The automotive structural component according to Solution 12, wherein the total Cr and Si content is less than or equal to about 5 wt%.
[0029] Solution 14. The automotive structural component according to Solution 13, wherein the Cr:Si ratio is about 1.25 to about 3.
[0030] Solution 15. The automotive structural component according to Solution 12, wherein the Cr:Si ratio is about 1.25 to about 3.
[0031] Solution 16. The automotive structural component according to Solution 11, wherein the component is an automotive pillar, door beam, or bumper beam. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The present disclosure is more fully understood from the detailed description and the drawings, wherein:
[0033] Figure 1Micrograph of 22MnB5 with a thick oxide after soaking at 930 °C for 300 seconds, showing a thick oxide layer of ~5 μm;
[0034] Figure 2 Micrograph of an alloy of 0.05 - 0.45 wt% C, 0 - 0.45 wt% Mn, 0.5 - 6 wt% Cr, 0.5 - 2.5 wt% Si, balance iron after soaking at 930 °C for 300 seconds, showing non-uniform oxidation from 0.2 μm to 3 μm;
[0035] Figure 3 Micrograph of an alloy according to the present disclosure after soaking at 930 °C for 640 seconds, showing uniform oxidation of approximately 0.14 μm;
[0036] Figure 4 Micrograph of an alloy according to the present disclosure after soaking at 930 °C for 720 seconds, showing uniform oxidation of approximately 0.16 μm;
[0037] Figure 5 Micrograph of an alloy according to the present disclosure after soaking at 930 °C for 300 seconds, showing uniform oxidation of approximately 0.13 μm;
[0038] Figure 6 Micrograph of an alloy according to the present disclosure after soaking at 950 °C for 360 seconds, showing uniform oxidation of approximately 0.13 μm;
[0039] Figure 7A and 7B Micrographs of the surfaces of an alloy according to the present disclosure (7A) vs. 22MnB5 (7B) using spot welding electrodes after 25 spot welds;
[0040] Figure 8A and 8B Micrographs of the surfaces of an alloy according to the present disclosure (8A) vs. 22MnB5 (8B) using spot welding electrodes after 59 spot welds;
[0041] Figure 9A and 9B Micrographs of the surfaces of an alloy according to the present disclosure (9A) vs. 22MnB5 (9B) using spot welding electrodes after 75 spot welds;
[0042] Figure 10A and 10B Micrographs of the surfaces of an alloy according to the present disclosure (10A) vs. 22MnB5 (10B) using spot welding electrodes after 100 spot welds; and
[0043] Figure 11A and 11BIllustration of spot welding electrodes after 100 spot welds of the current alloy (11A) vs. the alloys of the present disclosure.
[0044] In the figures, reference numerals may be reused to identify like and / or identical elements. Detailed Description
[0045] Embodiments of the present disclosure provide an improved metallic alloy suitable for hot stamping. According to a first preferred embodiment, the alloy may comprise from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities.
[0046] The cerium content is preferably higher than about 0.1 wt% to improve the surface quality after hot stamping. The cerium content is preferably less than about 0.5 wt% to maintain steel casting and rolling quality. In some versions of this first embodiment, it may be desirable to keep the sum of the Cr and Si contents less than or equal to about 5 wt% for easier removal of scale in the rolling mill. In some versions of this first embodiment, it may be desirable to keep the ratio of Cr:Si in the range of about 1.25:1 to about 3:1 for high temperature oxidation resistance during hot stamping. Of course, other rare earth materials may be used in place of cerium.
[0047] The alloy does not need to be processed in a protective atmosphere such as nitrogen or argon, etc., and the processing typically results in a thin, uniform oxide coating that is less than 1 μm thick, typically less than 0.5 μm thick, and typically in the range of 0.1 to 0.2 μm thick. The thinner and more uniform oxide layer is less damaging to the spot welding tip compared to the thicker and / or more non-uniform oxide coatings formed on existing hot stamping alloys.
[0048] According to a second preferred embodiment of the present disclosure, a method of manufacturing a structural component, such as an automotive structural component, is disclosed. The method according to this second preferred embodiment includes heating a metallic alloy blank that comprises from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities.
[0049] Heat the alloy to a temperature above its austenization temperature (~900 °C). Then hot stamp the heated metal blank into a desired structural component. The composition provides a wider processing window in terms of both temperature and duration. For example, in one version, the heating occurs in a space defined by the time-temperature points (300 s, 870 °C), (200 s, 980 °C), (800 s, 870 °C), and (1000 s, 980 °C). In another version, the heating occurs in a space defined by the time-temperature points (300 s, 870 °C), (200 s, 980 °C), (1000 s, 870 °C), and (800 s, 980 °C). In some cases, the heating can be carried out in an inert atmosphere, such as a nitrogen or argon atmosphere.
[0050] According to a third preferred embodiment of the present disclosure, it provides automotive components. According to the third embodiment, a structural component, such as an automotive structural component, is made of about 0.05 to about 0.45 wt% carbon; about 0.5 to about 4.5 wt% manganese; about 0.5 to about 6 wt% chromium; about 0.5 to about 2.5 wt% silicon, about 0.1 to about 0.5 wt% cerium, with the balance being iron and impurities, and is formed by hot stamping, and after hot stamping, it has a substantially uniform oxidation thickness of less than about 0.5 μm. For example, the component can be an automotive strut, a door beam, and a bumper beam.
[0051] The thin, substantially uniform oxide coating improves spot welding, extends the life of the spot welding electrodes, and inhibits spot welding melting / ejection, resulting in a smoother surface.
[0052] The foregoing description is illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses. The broad teachings of the present disclosure can be implemented in a variety of forms. Thus, while the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited because other modifications will become apparent after studying the drawings, the specification, and the appended claims. It should be understood that one or more steps within a method can be performed in a different order (or simultaneously) without changing the principles of the present disclosure. Additionally, although each of the embodiments above is described as having certain features, any one or more of those features described with respect to any embodiment of the invention can be implemented in and / or combined with the features of any one of the other embodiments, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more of the embodiments remain within the scope of the present disclosure.
Claims
1. A metal alloy suitable for hot stamping, said alloy comprising from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, the balance being iron and impurities.
2. The metal alloy according to claim 1, wherein the sum of the Cr and Si contents is less than or equal to about 5 wt%.
3. The metal alloy according to claim 2, wherein the ratio of Cr:Si is from about 1.25 to about 3.
4. The metal alloy according to claim 1, wherein the ratio of Cr:Si is from about 1.25 to about 3.
5. A method of manufacturing an automotive structural component, comprising: heating a metal alloy blank, said metal alloy blank comprising from about 0.05 to about 0.45 wt% carbon; from about 0.5 to about 4.5 wt% manganese; from about 0.5 to about 6 wt% chromium; from about 0.5 to about 2.5 wt% silicon, from about 0.1 to about 0.5 wt% cerium, the balance being iron and impurities; and hot stamping said blank into a desired automotive structural component.
6. The method according to claim 5, wherein said heating occurs in a space defined by the time, temperature points (300 s, 870 °C), (200 s, 980 °C), (800 s, 870 °C) and (1000 s, 980 °C).
7. The method according to claim 5, wherein said heating occurs in a space defined by the time, temperature points (300 s, 870 °C), (200 s, 980 °C), (1000 s, 870 °C) and (800 s, 980 °C).
8. The method according to claim 5, which further comprises wherein said heating is carried out in an inert atmosphere.
9. The method according to claim 5, wherein the composition of said blank has a sum of Cr and Si contents of less than or equal to about 5 wt%.
10. The method according to claim 9, wherein the composition of said blank has a Cr:Si ratio of from about 1.25 to about 3.