Inclusion Control Patents: Who Leads, Where the Gaps Are 2026
- 41.7% concentration. The top 5 of 94 ranked assignees account for 116 of 278 records in scope — a small group holding disproportionate ground in calcium treatment, reoxidation control and castability claims.
- Casting dominates the claim map. B22D metal casting appears in 56.5% of records, well ahead of C21C steelmaking (28.1%), pointing to where the densest prior art actually sits.
- Filings have cooled from their peak. After peaking at 7 in 2021, filings fell to 3 by 2024, a 57% drop over that span — though 2025-26 counts are still filling in as publications lag filing by roughly 18 months.
Filing growth compares 2021 (7 records) with 2024 (3) — 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 278 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape covers 278 published records filed between 2015 and 2026 that combine nonmetallic inclusion control, steel cleanliness and inclusion modification with the practical mechanisms that make or break castability: calcium treatment, reoxidation sources, inclusion flotation, automated inclusion analysis and nozzle clogging. The scope is deliberately narrow — it excludes general steelmaking and general casting art that does not tie back to inclusion behaviour or clogging risk.
Filing activity is spread across major steel-producing jurisdictions, with Japan, the United States and India as the leading receiving offices, followed by Europe, Australia and China. The technology composition skews heavily toward casting-stage control rather than melt chemistry alone, which matters for anyone deciding where to search before filing.
Filing trend and technology composition
Two views of the same 278-record set: how filing activity has moved year over year, and how records distribute across IPC subclasses.
Filing trend, 2017-2026
Filings rose to a peak of 7 in 2021 before falling to 3 by 2024, a 57% decline over that three-year window. Treat 2025 and 2026 as incomplete rather than as a continuation of the decline, since publication typically lags filing by around 18 months.
IPC subclass composition
B22D (metal casting) appears in 56.5% of the 278 records, C22C (alloys) in 42.8%, and C21C (steelmaking) in 28.1%. Because a record can carry multiple IPC classes, these shares sum to more than 100% and should be read against the 278-record total, not against each other.
Shares are the percentage of the 278 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Inclusion Control and Steel Cleanliness with Eureka
This page is one run against one query. Ask Eureka your own question about inclusion control and steel cleanliness and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
US5884685A — Quality prediction and quality control of continuous-cast steel
A rapid analysis device examines nonmetallic inclusions in steel using a cold crucible method, combined with a mathematical model that predicts cast steel quality online by simulating inclusion behaviour. Continuous casting process variables are then controlled to minimise the amount of nonmetallic inclusions in the cast steel.Filed via PCT (WO96/30141) and granted to Nippon Steel Corporation in 1999, this record ties inline inclusion analysis directly to closed-loop casting control.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | JP1982184563A | Powder for surface coating of molten metal in continuous casting | 52 |
| 2 | WO2003024644A1 | Casting steel strip | 51 |
| 3 | US6174347B1 | Basic tundish flux composition for steelmaking processes | 49 |
| 4 | US6039127A | Rock drill | 42 |
| 5 | US6908518B2 | Nickel base superalloys and turbine components fabricated therefrom | 35 |
| 6 | US5884685A | Quality prediction and quality control of continuous-cast steel | 35 |
| 7 | US20030111206A1 | Casting steel strip | 32 |
| 8 | JP1991110048A | Tundish stopper | 26 |
| 9 | US4481032A | Process for adding calcium to a bath of molten ferrous material | 26 |
| 10 | US4468249A | Machinery steel | 26 |
Citation counts reflect influence within the searched corpus and favour older filings; they are not a measure of current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Reading the concentration, composition and citation figures together points to where claim space is occupied and where it is thin.
A small group holds the core casting-stage art
The leader alone accounts for 47 records, and the top 5 combined for 116 of 278 records in scope. That concentration sits mostly in casting-stage control rather than melt chemistry, which is the harder area to design around.
Casting-stage claims dominate the field
B22D appears in more than half of all records, with C22C alloys and C21C steelmaking next. The comparatively thin presence of C21D heat treatment (12.2%) and B21B rolling (5.0%) suggests these downstream steps are less contested.
Activity has cooled from its 2021 peak
Filings peaked at 7 in 2021 and fell to 3 by 2024. Several of the most active historical filers show no filings in the latest tracked year, though this reflects the normal 18-month publication lag as much as any real slowdown.
Filing activity clusters in Japan, the US and India
Japan leads at 71 records, ahead of the United States (44) and India (41), with Europe, Australia and China trailing. This split reflects where steelmaking capacity and casting R&D investment are concentrated.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to inclusion control and steel cleanliness, with the prior art for and against each one.
Who is filing, and where the ground is open
The ranked field runs to 94 companies, but activity is heavily weighted toward a handful of steelmakers and refractory suppliers with long-running casting programmes.
A single assignee leads by a wide margin
The top-ranked assignee holds 47 records, well ahead of fifth place at 10 and tenth place at 6. That gap indicates a sustained, multi-decade filing programme rather than a single burst of activity.
A long tail of single- and few-filing entrants
Beyond the top 10, which together hold 54.7% of all 278 records, the remaining ranked assignees each hold small counts. This is typical of a field where refractory suppliers, ceramics makers and steelmakers all file opportunistically around a shared casting problem.
Co-filing is limited and concentrated
Only 10 co-assignee pairs appear in the dataset, the strongest linking a major Japanese steelmaker with its former parent group, and a US steelmaker with named individual inventors. Cross-company joint filing is the exception here, not the norm.
| Assignee | Recent year | YoY |
|---|---|---|
| Nucor Corp | 0 | — |
| Nippon Steel Corporation | 0 | -100% |
| Kawasaki Steel Corp | 0 | — |
| Tata Steel IJmuiden BV | 0 | — |
| LG Electronics Inc | 0 | — |
| Foseco International Ltd | 0 | — |
| Steel Authority of India Ltd | 0 | — |
| Toshiba Ceramics Co., Ltd. | 0 | — |
Where to take this next
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio strategy or R&D scoping.
Check freedom-to-operate on casting-stage claims
With 56.5% of records touching B22D and a top-5 concentration of 41.7% of all 278 records, any new casting-control filing should be checked against the leading assignees' claim scope before drafting.
Explore in EurekaScope R&D around under-claimed branches
Automated inclusion analysis and reoxidation diagnostics show thinner filing density than casting-stage control, making them candidates for faster, less contested filings.
Explore in EurekaTrack momentum, not just historical volume
Several top historical filers show no activity in the latest tracked year. Confirm whether that reflects genuine withdrawal or the 18-month publication lag before assuming the field has gone quiet.
Explore in EurekaCommon questions about this landscape
One assignee leads clearly with 47 of the 278 records in scope, well ahead of the fifth-placed company at 10 and the tenth at 6. The top 5 assignees together account for 41.7% of all records, and the top 10 for 54.7%. Beyond that, the ranking of 94 companies thins into a long tail of firms with only a handful of filings each, typical of refractory suppliers and ceramics makers filing around a shared casting problem.
Filings peaked at 7 in 2021 and fell to 3 by 2024, a 57% decline over that span. It would be a mistake to read the years after 2024 as continuing that fall, because patent publication typically lags filing by around 18 months, so the most recent years in any dataset are always undercounted. The honest read is that activity cooled from a 2021 high, with the true 2025-26 trend not yet visible.
B22D, metal casting, appears in 56.5% of the 278 records, making it the dominant IPC subclass by a wide margin. C22C (alloys) follows at 42.8% and C21C (steelmaking) at 28.1%, while heat treatment (C21D) and rolling (B21B) trail well behind. Because records often carry multiple IPC codes, these percentages overlap rather than sum to a whole, but the ranking itself is a reliable guide to where claim density is heaviest.
US5884685A, assigned to Nippon Steel Corporation, covers an online quality-prediction system that analyses nonmetallic inclusions using a cold crucible method combined with a mathematical model, then adjusts continuous casting variables in closed loop to minimise inclusions. It ties inline inclusion measurement directly to real-time casting control rather than covering inclusion analysis or casting control separately. New filings that combine offline or standalone inclusion imaging with separate manual process adjustment are less likely to fall inside its claim scope than systems that replicate the closed-loop link.
The clearest gaps sit adjacent to the dense casting-stage art: automated inclusion image analysis, reoxidation source diagnostics at ladle-to-mould transfer, and nozzle clogging prediction models all show thinner filing density than core casting control. These are technically specific enough to support a defensible first claim rather than being crowded fields dressed up as open ground. Confirming white space still requires a freedom-to-operate check against the leading assignees named in the ranking, since low volume in a subclass does not guarantee an empty claim space.
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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.