AHSS Welding Patents: Top Companies & Filing Trends 2026
- Filings peaked in 2017 at 186 and have declined since, with the most recent year understated by the usual 18-month publication lag but the downward trend visible well before that lag matters.
- Alloy composition and heat treatment dominate the claim space, C22C and C21D subclasses cover 2,231 and 1,832 records respectively, dwarfing the 390 records that sit specifically in B23K welding.
- Momentum has stalled across the named leaders, several top assignees show 0 filings or a -100% YoY drop in the latest year, while Baoshan Iron & Steel is one of the few still filing.
Filing growth compares 2021 (132 records) with 2024 (70) — 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 2,437 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patent families at the intersection of advanced high-strength steel (AHSS) composition and the joining processes used to assemble it into structures — principally resistance spot welding and laser welding — with particular attention to weldability and liquid metal embrittlement (LME), the cracking failure mode that shows up specifically when zinc-coated AHSS is spot welded. The search spans IPC classes covering welding equipment and process (B23K11, B23K26) alongside the alloy chemistry class (C22C38) that defines the steel grades being joined.
Coverage runs from 2015 through the 2026-07-31 cut-off, across 2,437 published records and an equal number of patent families — a corpus where family counts and document counts align closely, suggesting relatively little multi-jurisdiction refiling pressure on the same invention.
Filing trend and technology composition
The volume curve and the IPC breakdown together show where the claim pressure actually sits: not in the weld process itself, but in the steel that goes into the weld.
Filings rose through the mid-2010s, peaked, and have since declined
Annual filings climbed to a peak of 186 in 2017, held near the midpoint value of 119 by 2022, and dropped to 9 by 2026 — a partial year understated by the roughly 18-month gap between filing and publication, but consistent with a maturing, not expanding, claim space.
Alloy and heat-treatment classes outweigh welding-specific filings by a wide margin
C22C (alloys) and C21D (heat treatment) each cover more than three-quarters of the corpus, while B23K (welding, soldering & brazing) accounts for 390 records — a reminder that most of this landscape is steel metallurgy claimed with a welding-performance angle, not welding equipment or process innovation in isolation.
Shares are the percentage of the 2,437 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 Joining and Welding with Eureka
This page is one run against one query. Ask Eureka your own question about advanced high-strength steel joining and welding and every answer comes back with the patent numbers behind it.
Try EurekaThe records other filings cite most
Resistance spot welding of galvanized high-strength steel — Baoshan Iron & Steel
A three-pulse resistance spot welding schedule for galvanized AHSS: a first pulse sized to nugget diameter as a function of plate thickness, a second pulse that grows the nugget slowly, and a third tempering pulse that improves the plasticity of the weld spot — the whole sequence aimed at suppressing liquid metal embrittlement cracking during the weld itself rather than through coating or alloy changes.Filed as US20190321907A1, published 2019-10-24.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | JP1986157625A | Manufacture of high-strength steel sheet | 329 |
| 2 | EP2325346A1 | High-strength steel plate and manufacturing method thereof | 177 |
| 3 | JP2004332099A | High-strength thin steel sheet superior in hydrogen embrittlement resistance, weldability, hole-expandability… | 164 |
| 4 | JP2010115706A | Resistance spot welding method for high-strength steel sheet | 129 |
| 5 | JP2015093282A | Method for spot welding high-strength steel plate | 117 |
| 6 | US20110146852A1 | High strength steel sheet and method for manufacturing the same | 95 |
| 7 | EP0969112A1 | Dual-phase high-strength steel sheet having excellent dynamic deformation properties and process for preparin… | 92 |
| 8 | JP2010172946A | Resistance spot welding method of high-strength steel sheet | 81 |
| 9 | JP2012157900A | Projection weld joint and method for production thereof | 79 |
| 10 | CN101348885A | 一种1000MPa级冷轧热镀锌双相钢及其制造方法 | 78 |
Citation counts accumulate over time and favour older filings; treat this table as a map of foundational and frequently-referenced disclosures, not of current filing activity.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once volume, geography and citation weight are read together.
Growth has flattened, not accelerated
The 2017 peak of 186 filings has not been matched since; by the 2022 midpoint filings sat at 119, and the corpus has continued to thin out toward the data cut-off. Read the final years as a floor, not a forecast, given the usual reporting lag.
Most of the landscape is metallurgy, not weld process
Alloy composition (C22C) and heat treatment (C21D) together dominate the IPC mix, while dedicated welding-process claims (B23K) are a minority. Freedom-to-operate risk concentrates in steel chemistry claims more than in electrode, pulse or laser-parameter claims.
Europe leads filing volume, the US and India follow
Europe (829) outpaces the United States (491) and India (272) as a receiving office, with China (229), Canada (124) and Japan (119) trailing. A European filing strategy intersects with the densest part of this corpus.
The named leaders have gone quiet in the latest year
Nippon Steel, POSCO and Kobe Steel each show zero filings and a -100% year-on-year drop in the most recent year on record, while JFE Steel shows a steep decline and Baoshan Iron & Steel remains one of the few still filing.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to advanced high-strength steel joining and welding, with the prior art for and against each one.
Who holds the claims, and who is still filing
Ten co-assignee pairs and a handful of still-active filers define the current competitive structure. The strongest pairing links Nippon Steel to its former Sumitomo Metal joint entity, and Kobe Steel to a university technology-licensing partner — both signs of long-running institutional collaboration rather than new entrants.
Legacy steelmakers hold the deepest filing history
Japanese and Korean integrated steel producers account for the bulk of historical volume and the strongest co-assignee links, reflecting decades of joint alloy-and-process development between corporate parents and their metal divisions.
Baoshan Iron & Steel is one of the few still filing
While several established assignees show zero activity in the most recent year, Baoshan Iron & Steel continues to file, including the representative resistance-spot-welding record featured on this page.
Automakers appear as co-assignees, not just customers
The JFE Steel and Honda pairing signals joint development between steelmaker and OEM on weldability performance for automotive-grade AHSS, a pattern worth watching for future collaborations between materials suppliers and vehicle manufacturers.
| Assignee | Recent year | YoY |
|---|---|---|
| JFE Steel Corporation | 1 | -92% |
| Baoshan Iron & Steel Co., Ltd. | 1 | — |
| Nippon Steel Corporation | 0 | -100% |
| POSCO | 0 | -100% |
| Kobe Steel, Ltd. | 0 | -100% |
| NIPPON STEEL & SUMITOMO METAL CORP | 0 | — |
| ArcelorMittal | 0 | — |
| Sumitomo Metal Industries, Ltd. | 0 | — |
Where to take this analysis
The trend and ownership data point to specific next steps depending on whether the goal is freedom-to-operate, licensing or new filing strategy.
Map claim scope against the C22C alloy cluster
Since most filing pressure sits in alloy composition rather than weld process, a freedom-to-operate review should start with C22C38 grade claims before assessing weld-parameter novelty.
Explore alloy claim scope in EurekaTrack the quiet leaders for renewed activity
Nippon Steel, POSCO and Kobe Steel show zero recent filings; a licensing or watch strategy should monitor these portfolios for reactivation rather than assume abandonment.
Set up assignee monitoring in EurekaEvaluate the under-claimed welding-process branches
Laser-welding parameter control and multi-pulse spot-welding schedules beyond three pulses show comparatively thin dedicated coverage relative to alloy claims.
Run a white-space search in EurekaCommon questions about AHSS joining and welding patents
The strongest historical filing positions belong to Japanese and Korean integrated steelmakers, including Nippon Steel and its former Sumitomo Metal joint entity, Kobe Steel, POSCO and JFE Steel, alongside Baoshan Iron & Steel from China. Several of these established filers show zero filings in the most recent year on record, while Baoshan Iron & Steel remains active. The co-assignee data also shows steelmakers partnering with automakers, such as JFE Steel with Honda, on joint weldability development.
Liquid metal embrittlement (LME) is a cracking failure that occurs when zinc coating on galvanized AHSS melts locally during resistance spot welding and penetrates the base steel's grain boundaries under tensile stress. It matters for patent strategy because a meaningful share of the welding-specific claims in this landscape are built around suppressing LME cracks through pulse timing, current control or coating chemistry rather than through the base alloy itself. The representative filing in this dataset, from Baoshan Iron & Steel, claims a three-pulse welding schedule specifically designed to control nugget growth and suppress LME.
No — filings peaked at 186 in 2017 and have declined since, reaching 119 by the 2022 midpoint and falling further toward the 2026 cut-off. The final one or two years in any dataset are always understated because publication lags filing by roughly 18 months, but the decline is visible well before that lag becomes the explanation. This points to a claim space that has matured rather than one still in an expansion phase.
The IPC composition shows heavy concentration in alloy chemistry (C22C) and heat treatment (C21D), with welding-process claims (B23K) making up a much smaller share of the corpus. That imbalance suggests process-side branches — laser-welding parameter control, electrode geometry designed against LME, and multi-pulse spot-welding schedules beyond the common three-pulse pattern — carry comparatively less dedicated filing pressure and are worth a closer freedom-to-operate and white-space check before committing to a filing strategy.
Europe, filed through the EPO, leads as a receiving office with 829 records, ahead of the United States at 491 and India at 272. China, Canada and Japan follow with smaller but still meaningful volumes. A filing or clearance strategy focused on Europe intersects with the densest part of this patent corpus, while the US and India represent the next tier of filing activity.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
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.