AHSS Reliability Patents: Who Leads, Where the Gaps Are 2026
- Filing has cooled from its 2022 peak. 46 families filed in 2022 against 19 in 2017 and just 1 recorded so far in 2026 — a decline consistent with the usual 18-month publication lag, not necessarily a real drop in R&D.
- Heat treatment claims ride alongside almost every alloy filing. 331 records sit in C22C (alloys) and 278 overlap with C21D (heat treatment), showing reliability gains are being claimed as combined composition-plus-process, not composition alone.
- Filing is concentrated in Europe and the US, not in the largest steel-producing markets. 145 EPO filings and 67 US filings dwarf China's 10, suggesting the reliability and durability claim space is being built for export-market qualification rather than domestic protection.
Filing growth compares 2021 (6 records) with 2024 (11) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 335 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patent families addressing fatigue durability, hydrogen embrittlement resistance, crashworthiness and service durability claims made specifically against advanced high-strength steel (AHSS) and related high-strength steel compositions. The search combines title/abstract language on AHSS with IPC codes for alloy composition (C22C), mechanical testing (G01N3) and corrosion protection (C23F11), so it captures documents that pair a strength claim with an explicit reliability or durability test or failure mode.
335 patent families published between 2015 and mid-2026 meet this definition. The corpus skews toward automotive-grade steel: hydrogen embrittlement resistance and hole-expandability language recur across the most-cited records, and the IPC composition shows heat treatment and coating claims layered onto base alloy claims far more often than they stand alone.
Filing trend and technology composition
Annual filing counts and the IPC subclass breakdown, drawn directly from the 335 families in this corpus.
Filing trend, 2017–2026
Filings rose from 19 in 2017 to a peak of 46 in 2022, then declined toward the present; the final year or two of any such trend is always undercounted because publication typically lags filing by around 18 months.
IPC subclass distribution
C22C (alloys) and C21D (heat treatment of metals) dominate at 331 and 278 records respectively, with C23C (coating and surface deposition) a distant third at 80 — evidence that reliability claims are built on composition-plus-process combinations rather than composition alone.
Shares are the percentage of the 335 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Advanced High-Strength Steel Reliability and Durability with Eureka
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Try EurekaThe most-cited prior art in this space
High-strength steel material with excellent hydrogen embrittlement resistance
The invention provides a steel material with satisfactory hydrogen embrittlement resistance, and particularly it relates to high-strength steel with satisfactory hydrogen embrittlement resistance and a strength of 1200 MPa or greater, as well as a process for production thereof. At least one simple or compound deposit of oxides, carbides or nitrides as hydrogen trap sites which trap hydrogen with a specific trap energy is added to steel, where the mean sizes, number densities, and length-to-thickness ratios (aspect ratio) are in specific ranges.Filed by Nippon Steel Corporation, published 2011-11-03 as US20110268600A1.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | JP2004332099A | High-strength thin steel sheet superior in hydrogen embrittlement resistance, weldability, hole-expandability… | 164 |
| 2 | JP2008024980A | High-strength galvannealed steel sheet and producing method therefor | 61 |
| 3 | EP2703512A1 | High-strength steel plate with excellent formability and stability of material properties, and method for man… | 44 |
| 4 | US20110030854A1 | High-strength steel sheet and method for manufacturing the same | 44 |
| 5 | JP2008169475A | High-strength steel sheet | 44 |
| 6 | US20060191612A1 | High-strength steel sheet excellent in deep drawing characteristics and method for production thereof | 42 |
| 7 | JP2004332100A | High-strength thin steel sheet superior in hydrogen embrittlement resistance, weldability, and hole-expandabi… | 39 |
| 8 | US20110024004A1 | High-strength steel sheet and galvanized steel sheet having very good balance between hole expansibility and … | 37 |
| 9 | JP2010275608A | High-strength steel sheet having excellent hydrogen embrittlement resistance | 34 |
| 10 | EP2264206A1 | High-strength steel sheets which are extremely excellent in the balance between burring workability and ducti… | 28 |
Citation counts reflect influence within the searched corpus and favour older filings; they are not a measure of current commercial importance.
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Four patterns stand out once the filings are broken down by geography, technology overlap and citation weight.
The peak has passed, at least on paper
Filings peaked at 46 in 2022 and have fallen in every year since, with only 1 recorded so far in 2026. Given the usual 18-month lag between filing and publication, the true 2025–2026 volume is understated, but the multi-year decline from 2022 predates that lag effect.
Alloy claims rarely stand alone
331 records sit in the alloy composition class C22C, and 278 of those overlap with C21D heat treatment. Filing a bare composition claim without an accompanying processing route leaves it exposed to obviousness challenges given how thoroughly the combination space is already claimed.
Protection is concentrated in export-qualification markets
Europe (145) and the United States (67) together account for the large majority of receiving-office filings, while China and Canada each sit at 10. For a material category where China is a major producer, this points to reliability and durability claims being filed where automotive OEM qualification happens, not where the steel is made.
One foundational filing anchors the field
JP2004332099A, on hydrogen embrittlement resistance, weldability and hole-expandability in thin steel sheet, carries 164 citations — more than double the next-highest record. Anyone filing on hydrogen embrittlement resistance in thin sheet should expect this filing to surface in any freedom-to-operate search.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to advanced high-strength steel reliability and durability, with the prior art for and against each one.
Who holds the ground
Filing activity is dominated by a small group of steelmakers, with momentum flattening even for the most active filers.
The largest filer is holding steady, not accelerating
Nippon Steel recorded 1 filing in the latest year with 0% year-on-year change, while several other major steelmakers recorded zero filings in the same period. This is a corpus where past filing volume, not recent momentum, explains current position.
Co-filing is limited and mostly internal
Only 10 co-assignee pairs appear across the corpus, and the strongest pair links Nippon Steel to its former Nippon Steel & Sumitomo Metal entity — reflecting a corporate merger history rather than external collaboration.
Named-inventor filings cluster around a small group
Individual inventor Murakami Toshio appears in co-filing pairs with two different collaborators at 3 shared filings each, suggesting a specific research group or consultancy active in this niche outside the major corporate assignees.
| Assignee | Recent year | YoY |
|---|---|---|
| Nippon Steel Corporation | 1 | 0% |
| JFE Steel Corporation | 0 | -100% |
| Kobe Steel, Ltd. | 0 | — |
| POSCO | 0 | — |
| NIPPON STEEL & SUMITOMO METAL CORP | 0 | — |
| Tata Steel IJmuiden B.V. | 0 | — |
| MURAKAMI TOSHIO | 0 | — |
| MIZUTA NAOKI | 0 | — |
Where to take this analysis
The filing data points to a mature core and a thinner set of adjacent claim areas still open for differentiation.
Map the hydrogen embrittlement resistance sub-cluster in detail
With one filing carrying 164 citations and the representative record built entirely around hydrogen trap-site engineering, this sub-area deserves its own claim chart before any new composition work begins.
Explore hydrogen embrittlement filingsCheck the coating and welding branches for open claim space
C23C, B23K and C25D together cover under 110 records against 331 in C22C — durability claims tied to coating adhesion or weld-zone performance are comparatively underfiled.
Review coating and welding claimsWatch for continuation filings from the 2022 peak cohort
The largest single-year cohort filed in 2022; those families are due for continuation, divisional or foreign-counterpart activity that has not yet fully published.
Track 2022 cohort follow-onsCommon questions on AHSS reliability patents
This landscape defines advanced high-strength steel (AHSS) by title/abstract language referencing AHSS or high-strength steel combined with an explicit reliability or durability claim, such as fatigue durability, hydrogen embrittlement resistance, crashworthiness or service durability. It does not capture every high-strength steel patent, only those that pair a strength claim with a named failure mode or durability test. This narrows the corpus to 335 families, mostly automotive-grade sheet steel, rather than the broader universe of alloy steel patents.
Filings peaked at 46 in 2022 and have fallen in each subsequent year, reaching just 1 recorded so far in 2026. Part of this drop is a publication artefact: patent applications typically publish 18 months or more after filing, so 2025 and 2026 figures will rise as later disclosures come through. That said, the decline is visible starting from 2022 itself, well before the lag window, which suggests filing activity genuinely cooled rather than simply appearing delayed.
The single most-cited record in this corpus, JP2004332099A, covers a high-strength thin steel sheet engineered for hydrogen embrittlement resistance, weldability, hole-expandability and ductility, with 164 citations — far ahead of any other record. Nippon Steel also holds a representative filing, US20110268600A1, built around engineered hydrogen trap sites in steel exceeding 1200 MPa strength. Any new filing targeting hydrogen embrittlement resistance in thin sheet should expect both to surface in a freedom-to-operate search.
The IPC breakdown shows heavy concentration in alloy composition (331 records) and heat treatment (278), with coating, welding and electroplating classes far thinner by comparison — under 110 records combined across C23C, B23K and C25D. Sub-areas such as weld-zone hydrogen trapping, resistance-spot-weld fatigue life and electroplated coating adhesion under cyclic load show comparatively little dedicated claim coverage relative to the core alloy-plus-heat-treatment combination. These are reasonable areas to check before assuming the core composition space is the only viable filing target.
The European Patent Office leads with 145 filings, followed by the United States at 67, then India at 44, Japan at 16, and Canada and China tied at 10 each. This distribution is notable because China, a major steel producer, shows far fewer filings than Europe or the US, implying that reliability and durability claims in this space are being filed predominantly where automotive OEM qualification and export markets are concentrated rather than where the steel itself is manufactured.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.