US 11326227

US patent 11326227, titled "Coated steel strips, coated stamped products and methods," was issued on May 10, 2022. The application was filed on May 13, 2021, by ArcelorMittal SA, which is also the current assignee. The inventors are Pascal Drillet, Dominique Spehner, and Ronald Kefferstein.

Abstract:
The patent describes a pre-coated steel strip. This strip consists of a base steel strip with a length of at least 100 meters and a width of at least 600 millimeters. At least part of one side of the steel strip has an aluminum or aluminum alloy pre-coating. A key feature is that the thickness of this pre-coating (tp) is precisely controlled to be between 20 and 33 micrometers at every location on the coated side(s). The patent also covers related processes, the resulting coated stamped products, and their use in land motor vehicles.

Independent Claims Overview:

Claim 1 (Hot Stamped Coated Steel Product):
This claim describes a hot stamped coated steel product. It comprises:

• A base steel strip with a first and a second side.
• A coating on at least one of these sides. This coating is formed through the interdiffusion of the base steel and an initial aluminum or aluminum alloy pre-coating.
• The coating, moving outwards from the base steel, consists of four distinct layers: (a) an Interdiffusion layer, (b) an Intermediate layer, (c) an Intermetallic layer, and (d) a Superficial layer. Each of these four layers has a different average chemical composition.
• The total thickness of this final coating (layers a, b, c, and d combined) is greater than 30 micrometers.

Litigation Status:
The patent family for US11326227 has several litigation events. This includes two PTAB (Patent Trial and Appeal Board) cases, IPR2024-01377 and IPR2025-00371, both of which were filed but not instituted procedurally. Additionally, there are US cases filed in the International Trade Commission (337-TA-3738 and 337-TA-1402) and a US case filed in the California Central District Court (2:24-cv-03128). While general CAFC case information is available, no specific CAFC 2026 dockets for US11326227 were found in the direct search results.

Known litigation involving US patent 11326227 as of April 26, 2026, is listed below, based on available information from Google Patents:

• PTAB Case

  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Case Number: IPR2024-01377
  • Filing Date: Not explicitly provided, but inferred to be in 2024 based on the case number.
  • Plaintiff(s): Not explicitly named in the provided information (listed as "Petitioner:" with no specific name).
  • Defendant(s): Not explicitly named (likely the patent owner, ArcelorMittal SA).
  • Outcome/Current Status: Not Instituted - Procedural.

• PTAB Case

  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Case Number: IPR2025-00371
  • Filing Date: Not explicitly provided, but inferred to be in 2025 based on the case number.
  • Plaintiff(s): Not explicitly named in the provided information (listed as "Petitioner:" with no specific name).
  • Defendant(s): Not explicitly named (likely the patent owner, ArcelorMittal SA).
  • Outcome/Current Status: Not Instituted - Procedural.

• US Case in International Trade Commission

  • Jurisdiction: International Trade Commission (ITC)
  • Case Number: 337-TA-3738
  • Filing Date: Not explicitly provided.
  • Plaintiff(s): Not explicitly provided.
  • Defendant(s): Not explicitly provided.
  • Outcome/Current Status: Not explicitly provided.

• US Case in International Trade Commission

  • Jurisdiction: International Trade Commission (ITC)
  • Case Number: 337-TA-1402
  • Filing Date: Not explicitly provided.
  • Plaintiff(s): Not explicitly provided.
  • Defendant(s): Not explicitly provided.
  • Outcome/Current Status: Not explicitly provided.

• US Case in California Central District Court

  • Jurisdiction: California Central District Court
  • Case Number: 2:24-cv-03128
  • Filing Date: Not explicitly provided.
  • Plaintiff(s): Not explicitly provided.
  • Defendant(s): Not explicitly provided.
  • Outcome/Current Status: Not explicitly provided.

Proceedings overview

One AIA trial proceeding is on file for US11326227. This proceeding resulted in a Final Written Decision denying institution on discretionary grounds, meaning the patent's claims were not evaluated on their merits. This posture indicates that the patent has not been subjected to a full IPR trial, and thus its claims remain untested for patentability challenges at the PTAB.

IPR2025-00371 — POSCO Co., Ltd. et al. v. ArcelorMittal

• Type: Inter Partes Review
• Filed: 2024-12-23
• Status: Final Written Decision — Institution of the IPR was denied on discretionary grounds, meaning the patentability of the claims was not reviewed on its merits.
• Judge panel: Acting Director Coke Morgan Stewart. The decision to deny institution was made by the Acting Director, likely in consultation with Administrative Patent Judges.
• Petition grounds: The specific claims and prior art challenged in the petition are not detailed in the public search results. However, the Director's decision to deny institution was influenced by the fact that "the Board previously determined related claims to be unpatentable—prior to the issuance of the challenged claims in this proceeding".
• Institution decision: Denied on June 25, 2025, as documented in "Paper 10" for both IPR2025-00370 and IPR2025-00371. The denial was based on discretionary factors, particularly the "settled expectations" doctrine, where the patent's age and prior Board determinations on related claims weighed against institution.
• Final Written Decision: A Final Written Decision on the merits of patentability was not issued because institution of the IPR was denied. The status "Final Written Decision" in the provided prompt likely refers to the Director's decision denying institution, which concluded the proceeding.
• Settlement / termination: The proceeding was terminated by the Director's decision to deny institution. No settlement was reported.
• Appeal: Decisions to deny institution are generally considered "final and non-appealable" under 35 U.S.C. § 314(d). While there have been challenges to Director denials at the Federal Circuit, these have often been unsuccessful.
• Defensive value: This proceeding did not result in a merits-based determination of patentability for any claims of US11326227. Therefore, the patent's claims remain untested by IPR challenges. A defendant facing assertion of this patent could still pursue an IPR on the merits if not in privity with POSCO Co., Ltd. et al., though the discretionary denial factors, such as "settled expectations," would need to be carefully considered.

Strategic summary

All claims of US11326227 remain UNTESTED in an inter partes review on their merits. The sole proceeding, IPR2025-00371, concluded with a discretionary denial of institution, meaning the PTAB did not proceed to a full trial to assess the patentability of the challenged claims against prior art.

Regarding the estoppel landscape, under 35 U.S.C. § 315(e)(2), the petitioner, POSCO Co., Ltd. et al., and any parties in privity with them, would be estopped from asserting in a civil action or another USPTO proceeding that a claim is invalid on any ground that was raised or reasonably could have been raised in IPR2025-00371, even though institution was denied. For a defendant not affiliated with POSCO, all prior-art grounds remain available for challenge, subject to the PTAB's current discretionary denial policies, particularly the "settled expectations" doctrine which played a role in this denial.

The denial of institution in IPR2025-00371 aligns with a recent trend at the PTAB, led by Acting Director Coke Morgan Stewart, towards a more flexible approach to discretionary denials, including the consideration of "settled expectations" based on the patent's age and prior Board determinations. This signals a potentially higher bar for instituting IPRs, especially for older patents or those with a history of related challenges.

Recommended next steps

The institution of IPR2025-00371 was denied on June 25, 2025, as outlined in Paper 10 for the proceeding. This decision can be found in public records related to PTAB discretionary denials. As institution was denied, there is no Final Written Decision on the merits of the challenged claims to link to or quote a disposition from.

For a defendant currently being asserted against, the absence of a merits-based IPR decision means that the patent's claims have not been legally affirmed or canceled by the PTAB. Any new IPR petition would need to carefully address the discretionary factors that led to the denial of IPR2025-00371, particularly "settled expectations," to increase the likelihood of institution.

Inventors

• Pascal Drillet (ArcelorMittal SA)
• Dominique Spehner (ArcelorMittal SA)
• Ronald Kefferstein (ArcelorMittal SA)

All inventors appear to be associated with ArcelorMittal SA at the time of filing, as indicated by the assignment records. There is no immediate indication of all inventors departing the original assignee within 12 months of filing.

Original assignee

The original assignee named on the issued patent is ArcelorMittal SA. ArcelorMittal SA is a multinational steel manufacturing corporation and ships products embodying the claims (coated steel strips, hot stamped products). Its primary line of business is steel production and mining. ArcelorMittal SA is currently an operating company.

Assignment timeline

• 2021-05-13 (executed) / recorded 2021-05-13 — Reel 056461/0002

  • Conveyance: Assignment
  • Assignor: SPEHNER, DOMINIQUE
  • Assignee: ARCELORMITTAL FRANCE
  • Correspondent: MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP, 300 SOUTH WACKER DRIVE, CHICAGO, ILLINOIS, UNITED STATES, 60606
  • Context: Internal reorg (assignment from inventor to a subsidiary).

• 2021-05-13 (executed) / recorded 2021-05-13 — Reel 056461/0003

  • Conveyance: Assignment
  • Assignor: KEFFERSTEIN, RONALD
  • Assignee: ARCELORMITTAL
  • Correspondent: MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP, 300 SOUTH WACKER DRIVE, CHICAGO, ILLINOIS, UNITED STATES, 60606. This correspondent recurs in this chain.
  • Context: Internal reorg (assignment from inventor to the parent company).

• 2021-05-13 (executed) / recorded 2021-05-13 — Reel 056461/0004

  • Conveyance: Assignment
  • Assignor: DRILLET, PASCAL
  • Assignee: ARCELORMITTAL
  • Correspondent: MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP, 300 SOUTH WACKER DRIVE, CHICAGO, ILLINOIS, UNITED STATES, 60606. This correspondent recurs in this chain.
  • Context: Internal reorg (assignment from inventor to the parent company).

• 2021-05-13 (executed) / recorded 2021-05-13 — Reel 056461/0005

  • Conveyance: Assignment
  • Assignor: ARCELORMITTAL FRANCE
  • Assignee: ARCELORMITTAL
  • Correspondent: MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP, 300 SOUTH WACKER DRIVE, CHICAGO, ILLINOIS, UNITED STATES, 60606. This correspondent recurs in this chain.
  • Context: Internal reorg (assignment from subsidiary to parent company).

• 2021-05-13 (executed) / recorded 2021-05-13 — Reel 056461/0006

  • Conveyance: Assignment
  • Assignor: ARCELORMITTAL
  • Assignee: ARCELORMITTAL S.A.
  • Correspondent: MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP, 300 SOUTH WACKER DRIVE, CHICAGO, ILLINOIS, UNITED STATES, 60606. This correspondent recurs in this chain.
  • Context: Internal reorg (assignment within the ArcelorMittal corporate structure to the SA entity).

Timeline diagram

timeline
    title Ownership of US 11326227
    2021 : Inventors assigned to ArcelorMittal France
         : Kefferstein assigned to ArcelorMittal
         : Drillet assigned to ArcelorMittal
         : ArcelorMittal France assigned to ArcelorMittal
         : ArcelorMittal assigned to ArcelorMittal S.A.
    2022 : Patent issued

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The assignees are all variations of ArcelorMittal, a known operating company.
2. Known asserter in the chain — not present. None of the assignees (ArcelorMittal France, ArcelorMittal, ArcelorMittal S.A.) appear on common NPE lists.
3. Repeat correspondent across the chain — present. MCDONNELL BOEHNEN HULBERT & BERGHOFF LLP appears as the correspondent for all recorded assignments on 2021-05-13 (Reel 056461/0002, 056461/0003, 056461/0004, 056461/0005, 056461/0006). This indicates a consistent legal firm handling internal transfers for ArcelorMittal.
4. Cascading transfers — not present. While there are multiple transfers on the same day, they appear to be internal reorganizations within the ArcelorMittal corporate structure, not chained transfers between unrelated LLCs.
5. Pre-litigation transfer — unclear. The transfers occurred in 2021, and the patent issued in 2022. There is no information provided about any litigation related to this patent.
6. Bankruptcy fire-sale — not present. ArcelorMittal is an active operating company.
7. Privateering — not present. There is no indication of a transfer to an NPE for assertion on behalf of ArcelorMittal.
8. Defensive aggregator (anti-NPE) — not present. The chain ends at ArcelorMittal S.A., an operating company, not a defensive aggregator.

Verdict

Insufficient data. While there are multiple assignments, they all appear to be internal transfers within the ArcelorMittal corporate structure, a known operating company. There is no evidence of a transfer to a shell entity or a known NPE, and no information regarding any litigation.

USPTO Assignment Center Search: https://assignmentcenter.uspto.gov/

US patent 11326227, titled "Coated steel strips, coated stamped products and methods," describes a pre-coated steel strip comprising a base steel strip and an aluminum or aluminum alloy pre-coating. The pre-coating has a specific thickness range of 20 to 33 micrometers to prevent roller fouling during heat treatment and to ensure good weldability and mechanical properties after hot stamping. The patent also details a specific four-layer coating structure (interdiffusion, intermediate, intermetallic, and superficial layers) that forms after heat treatment and hot stamping, which is beneficial for welding. The steel itself is often an ultra-high-strength steel, such as boron steel, with controlled sulfur content for improved ductility.

The most relevant prior art cited in US patent 11326227 are:

1. US Patent No. 6,296,805

   • Full Citation: U.S. Pat. No. 6,296,805.
   • Publication/Filing Date: The patent itself was granted on October 2, 2001. The filing date of the application leading to this patent is not explicitly stated in the provided text but is implied to be prior to the publication date.
   • Brief Description: This patent is incorporated by reference in US11326227B2 and is mentioned in the context of hot forming followed by rapid cooling to obtain predominantly martensitic structures. It teaches the general process of heating blanks to achieve alloying of the steel substrate with a pre-coating and austenitizing the steel, followed by hot forming and rapid cooling.
   • Potential Anticipated Claim(s) under 35 U.S.C. § 102: Claims 1 (hot stamped coated steel product) and 15 (fully martensitic product) could be potentially anticipated by the general process of hot forming and rapid cooling to obtain predominantly martensitic structures. While US11326227B2 specifies a four-layer coating structure and a precise pre-coating thickness, the broad concept of obtaining martensitic structures through hot stamping and rapid cooling is acknowledged as prior art from US 6,296,805.

2. WO2008053273A1

   • Full Citation: WO2008053273A1.
   • Publication/Filing Date: International Patent Application PCT/IB06/004019 was filed on October 30, 2006. This is identified as the national phase application for US 11326227 B2.
   • Brief Description: This international application is a direct parent application to US 11326227 B2, meaning it covers the same or very similar subject matter. It broadly describes coated steel strips, methods of making and using them, stamping blanks, and stamped products, particularly in the context of automotive applications. It discusses a pre-coating of aluminum or an aluminum alloy on a base steel strip, with the strip having a length greater than 100m and a width greater than 600mm. It also mentions the formation of intermetallic layers after heat treatment and the goal of high mechanical resistance exceeding 1000 MPa.
   • Potential Anticipated Claim(s) under 35 U.S.C. § 102: Given that WO2008053273A1 is a direct priority document, it could potentially anticipate many, if not all, of the claims of US 11326227 B2. Specifically, claims 1, 16, 17, and 24, which describe the general characteristics of the coated steel product (base steel with Al/Al alloy coating, specific dimensions, certain steel compositions, and mechanical strength), appear to be broadly covered. The detailed layered structure of claims 1(ii)(a)-(d) and the specific thickness ranges are further refinements in the granted US patent.

3. US Patent No. 2,526,227A

   • Full Citation: US2526227A.
   • Publication/Filing Date: Patented October 17, 1950. Filing date: July 21, 1948.
   • Brief Description: This patent describes aluminum base alloys, specifically those containing magnesium, silicon, zinc, titanium, and chromium, which are suitable for castings, particularly for cooking utensils. It focuses on improved fluidity, freedom from surface pitting, and corrosion resistance for cast articles.
   • Potential Anticipated Claim(s) under 35 U.S.C. § 102: This patent is less directly relevant to hot-stamped coated steel strips. While it deals with aluminum alloys and corrosion resistance, it is focused on cast aluminum base alloys for cookware, not coatings on steel for hot stamping. Therefore, it is unlikely to directly anticipate any claims in US 11326227 B2. It might be cited for the general knowledge of aluminum alloy compositions, but not for the specific application or layered coating structure.

4. US Patent No. 11,326,222B2

   • Full Citation: US11326222B2.
   • Publication/Filing Date: Publication date: May 10, 2022. Filing date: November 28, 2018.
   • Brief Description: This patent describes an austenitic stainless steel containing niobium and a manufacturing method for the same. It focuses on modifying physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment, particularly for plates or strips.
   • Potential Anticipated Claim(s) under 35 U.S.C. § 102: This patent is unlikely to directly anticipate claims in US 11326227 B2 because it concerns austenitic stainless steel with niobium, not aluminum- or aluminum alloy-coated carbon or boron steel, nor the specific layered coating structure described in US 11326227 B2. However, it does share broad classifications related to heat treatment and modifying physical properties of ferrous metals during manufacturing of plates or strips, which might be considered generally relevant to the field but not specific to the invention's unique combination of features.

The provided patent text for US11326227 explicitly cites only one specific prior art reference, U.S. Pat. No. 6,296,805, within its "BACKGROUND OF THE INVENTION" section. This patent is referenced as an example of existing hot-stamping processes for shaping parts using pre-coated steels, which involve pre-coating by hot dipping, heating for alloying and austenitizing, and hot forming with rapid cooling to obtain predominantly martensitic structures.

Given that the request is to identify "combinations of prior art references" to render the claims obvious under 35 U.S.C. § 103, and only one specific prior art patent (U.S. Pat. No. 6,296,805) is explicitly cited and discussed in the provided "Prior Art section" (interpreted as the "BACKGROUND OF THE INVENTION"), it is not possible to construct an obviousness argument based on combinations of multiple specific prior art references from the given information.

However, an obviousness analysis typically considers what a person having ordinary skill in the art (PHOSITA) would have known or been motivated to do based on the collective knowledge of the field. The patent itself describes the general state of the art.

Analysis of Obviousness under 33 U.S.C. § 103 for US11326227, in light of available prior art information:

Independent Claim for Analysis (Claim 1):
Claim 1 of US11326227 recites:
"1. A hot stamped coated steel product, which comprises:
(a) a strip of base steel having a first side and a second side; and
(b) a coating on at least one of said first side of said strip of base steel and said second side of said strip of base steel, wherein:
(i) said coating results from interdiffusion between said base steel and an aluminum or aluminum alloy pre-coating, and
(ii) wherein said coating comprises, proceeding from the base steel outwards:
(a) an Interdiffusion layer,
(b) an Intermediate layer,
(c) an Intermetallic layer, and
(d) a Superficial layer,
wherein layers (a), (b), (c), and (d) each have a different mean composition from one another,
wherein said coating of the hot stamped coated steel product has a thickness greater than 30 micrometers."

Elements known in the prior art (from the patent's own disclosure):

• Hot stamped coated steel product: The patent explicitly states that the "use of pre-coated steels in hot-stamping processes for the shaping of parts has become important, especially in the automotive industry."
• Strip of base steel: Implied by "pre-coated steels" and "steel sheets."
• Coating resulting from interdiffusion between base steel and an aluminum or aluminum alloy pre-coating: The background mentions "Pre-coating of a steel sheets, by hot dipping" and "Heating the blanks in order to obtain alloying of the steel substrate with the pre-coating." This alloying process inherently leads to interdiffusion and the formation of alloyed layers. The patent also refers to "aluminized and hot stamped parts."
• General concept of multiple layers in the coating: The patent describes a prior art coating as having "interdiffusion layer and intermetallic layer" (as illustrated in FIG. 2, which does not correspond to the invention), indicating that multi-layered coatings formed by interdiffusion in hot-stamped parts were known.

Key Differentiating Features of Claim 1:

The key distinguishing feature of Claim 1 over the general prior art described in the patent, including the example of U.S. Pat. No. 6,296,805, lies in the specific four-layer structure of the coating, proceeding from the base steel outwards: (a) Interdiffusion layer, (b) Intermediate layer, (c) Intermetallic layer, and (d) Superficial layer, where "layers (a), (b), (c), and (d) each have a different mean composition from one another," and the total thickness of the coating is "greater than 30 micrometers." The patent highlights that this specific four-layer arrangement is "particularly favorable for the further welding of the part" and leads to "particularly good weldability." In contrast, the coating structure of FIG. 2, described as "interdiffusion layer and intermetallic layer," "yields inferior results in resistance spot welding."

Hypothetical Obviousness Argument (with limitations):

To demonstrate obviousness of Claim 1, one would hypothetically need:

1. A primary reference (e.g., U.S. Pat. No. 6,296,805 or similar general knowledge documented in prior art): This reference would establish the known practice of hot stamping aluminum or aluminum alloy pre-coated steel to create interdiffused coatings for high-strength parts. Such a reference would teach a hot stamped coated steel product comprising a strip of base steel with a coating resulting from interdiffusion with an Al or Al alloy pre-coating, thereby forming at least some alloyed layers.

2. Missing elements: The primary reference would likely not explicitly teach the specific four-layer structure ((a) Interdiffusion, (b) Intermediate, (c) Intermetallic, (d) Superficial) where all four layers have different mean compositions, nor that the total coating thickness is greater than 30 micrometers. The patent itself presents this specific layer succession as a discovery for improved weldability.

3. Secondary References (not explicitly provided in the patent text): To render Claim 1 obvious, one would need additional prior art references, or clear evidence of general knowledge, that would suggest to a PHOSITA:

   • The existence and characteristics (composition, hardness) of the "Intermediate" and "Superficial" layers as distinct phases in Al-Fe-Si systems after heat treatment.
   • A motivation to modify the known coating structures (like the two-layer structure in FIG. 2) to include these additional layers, specifically to achieve improved weldability or other benefits claimed by the invention (e.g., resistance to roller fouling, though the claim is for the product).
   • That controlling the overall coating thickness to be greater than 30 micrometers would lead to predictable benefits in terms of coating morphology or performance.

4. Motivation to Combine: Assuming such secondary references existed, a PHOSITA might be motivated to combine them with the teachings of a primary reference like U.S. Pat. No. 6,296,805 if:

   • The problems identified by the present invention (e.g., roller fouling, inferior weldability of existing coated parts) were well-known and there were known solutions in the art involving manipulating coating layer structures or thicknesses.
   • The secondary references suggested that the formation of specific additional intermetallic phases (like the 'Intermediate' and 'Superficial' layers) and their precise positioning could lead to predictable improvements in coating performance, such as resistance spot weldability.
   • Optimizing coating thickness was a common practice in the field to enhance properties like corrosion resistance, paint adhesion, or metallurgical interaction with the substrate. The patent describes that for a pre-coating thickness less than 20 micrometers, adhesion of painting is low and corrosion resistance is decreased, and if more than 33 micrometers, alloying may be insufficient. This implies that there was a known range, and the invention precisely defines a beneficial range.

Conclusion regarding provided information:

Based solely on the explicit prior art references and background disclosed within the provided text of US11326227, it is not possible to identify "combinations of prior art references" that would render Claim 1 obvious. The patent itself identifies U.S. Pat. No. 6,296,805 as illustrative of the general field of hot stamping pre-coated steels and then presents the specific four-layer coating structure as an inventive solution to known problems, contrasting it with a simpler, less effective coating. Without additional specific prior art references that teach or suggest the particular intermediate and superficial layers, their compositions, or the specific arrangement and total thickness claimed, and a motivation to combine them, a robust obviousness argument cannot be fully constructed using only the provided text.