Continuous Annealing Line Patents: Who Leads, Filing Trends 2026
Continuous annealing line patents: who holds the claim space and where it is still open
68.4% concentration. The top five assignees alone hold 1,898 of 2,776 records in scope — a field dominated by a small group of integrated steel producers. Filings peaked at 118 in 2017 and had fallen to 47 by 2024, a 39% drop from the 77 filed in 2021 — the last three-year span that can be read as complete. Data past 2024 is still arriving as later applications publish.
- 1JFE STEEL CORP759
- 2NIPPON STEEL CORPORATION476
- 3KAWASAKI STEEL CORP316
- 4ARCELORMITTAL SA203
- 5NIPPON KOKAN KK144
See the full continuous annealing lines analysis in Eureka
- The complete ranking, not just the top five
- Every IPC branch with its share of the corpus
- The most-cited records, and where claim space is still thin
Common questions about continuous annealing line patents
Who holds the most patents on continuous annealing lines?
Filing in this field is concentrated among a small number of integrated steel producers, with the leading assignee alone holding 759 of the 2,776 records in scope. The top five assignees combined hold 1,898 records, or 68.4% of the total, and the top ten reach 84.1%. This means any new entrant is filing against a small, well-established set of incumbents rather than a fragmented competitive field.
Is continuous annealing line patent activity growing or shrinking?
Filing peaked at 118 records in 2017 and has since cooled; from 2021 (77 filings) to 2024 (47 filings) volume fell 39%, and 2024 is the most recent year that can be read as complete. Because publication lags filing by roughly 18 months, the 2025 and 2026 figures in any trend chart are still filling in and should not be read as a further decline. The honest read is a maturing field with reduced but ongoing activity, not a field in collapse.
What technology areas do continuous annealing line patents cover?
The large majority, 82.2% of the 2,776 records, carry a C21D heat-treatment classification, with C22C alloy claims close behind at 52.2%. Coating and surface deposition (C23C) and layered products (B32B) appear on meaningfully smaller shares, and furnace hardware classes F27B and F27D each sit near 2%. Since a single record can carry several IPC classes, these shares overlap and add to more than 100%.
Disclaimer. This analysis is based on Patsnap Eureka data drawn from a limited snapshot of global patent records and is provided for general information and reference only. Patent data carries inherent limitations — recent filings are under-counted because of publication lag, counts may be on a record or family basis, classification and applicant-name data may contain errors or duplicates, and the underlying search query defines the scope shown — so the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing here is an exhaustive prior-art, novelty, freedom-to-operate or validity search, nor does it constitute legal, financial or professional advice, and it should not be relied upon as such. Verify independently and review with qualified patent and legal professionals before acting on it.
Method: Filing trend and technology composition. Derived from a Patsnap search on Continuous Annealing Lines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish. Every share divides by all records in scope. Data: Patsnap Eureka. See the full landscape report.