Ferritic Stainless Steel for Automotive Exhaust Patents: Top Companies 2026
- 42.2% of all 4,851 records sit with just five assignees — filing here means designing around an occupied top tier, not an open field.
- Filings fell 39% from 2021 to 2024 (100 → 61), a genuine slowdown on the last complete years, not an artefact of publication lag.
- C22C alloy claims cover 63.5% of records while exhaust-specific F01N classification appears in only 7.6% — most of the IP sits in the metallurgy, not the exhaust hardware.
Filing growth compares 2021 (100 records) with 2024 (61) — 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 4,851 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks 4,851 patent records published between 2015 and mid-2026 that combine ferritic stainless steel or niobium-stabilised grades with the automotive exhaust operating envelope: thermal fatigue, condensate corrosion, ridging, formability and high-temperature oxidation resistance. The scope spans both alloy composition claims and the heat-treatment routes used to reach them, which is why alloy and heat-treatment IPC classes dominate the composition breakdown even though the underlying application is exhaust hardware.
Filing activity peaked in 2017 at 179 records and has since declined on a multi-year basis, with the last fully comparable window (2021 to 2024) down 39%. Because publication typically lags filing by around eighteen months, the final one or two years in any chart will always look thinner than they will eventually turn out to be — that lag explains part of the recent-year drop-off but not the multi-year trend.
Filing trends and technology composition
Two views of the same 4,851-record corpus: how filing volume has moved year over year, and how those records distribute across IPC subclasses.
Filing activity, 2017-2026
Volume peaked at 179 records in 2017. The 2021→2024 window, the most recent span with complete publication, shows filings falling from 100 to 61 — a 39% decline. Treat 2025 and 2026 figures as provisional given the typical 18-month publication lag.
IPC subclass distribution
C22C (alloys) appears in 63.5% of records and C21D (heat treatment) in 33.4%, confirming this is primarily a metallurgy and processing patent set. Application-side classes are thinner: F01N (exhaust systems) at 7.6% and B23K (welding/brazing, relevant to exhaust joining) at 4.7%. Records can carry multiple classes, so shares sum above 100%.
Shares are the percentage of the 4,851 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ferritic Stainless Steel for Automotive Exhaust with Eureka
This page is one run against one query. Ask Eureka your own question about ferritic stainless steel for automotive exhaust and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
US20150345361A1 — Ferritic Stainless Steel for Automotive Exhaust System
Filed by POSCO, this application claims a ferritic stainless steel with corrosion resistance against condensate, moldability and high-temperature oxidation resistance, achieved without expensive alloying additions. The composition specifies tight bands for carbon, chromium, silicon, titanium and tin, with Sn concentrated at the surface as the distinguishing mechanism.Published 2015-12-03 — one of the field's foundational condensate-corrosion compositions.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US7121342B2 | Thermal processes for subsurface formations | 428 |
| 2 | US7073578B2 | Staged and/or patterned heating during in situ thermal processing of a hydrocarbon containing formation | 331 |
| 3 | US5684352A | Permanent magnet field-type rotating machine | 280 |
| 4 | US20080128134A1 | Producing drive fluid in situ in tar sands formations | 261 |
| 5 | US20090189617A1 | Continuous subsurface heater temperature measurement | 258 |
| 6 | US20080174115A1 | Power systems utilizing the heat of produced formation fluid | 258 |
| 7 | US20090071652A1 | In SITU heat treatment from multiple layers of a tar sands formation | 245 |
| 8 | US20040146288A1 | Temperature limited heaters for heating subsurface formations or wellbores | 239 |
| 9 | US20050006097A1 | Variable frequency temperature limited heaters | 239 |
| 10 | US20040140096A1 | Insulated conductor temperature limited heaters | 239 |
Citation counts favour older filings still active in the searched corpus; treat them as a measure of influence within this dataset rather than of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the data means for filing strategy
Three patterns stand out once volume, composition and timing are read together.
The top tier already occupies the core composition space
Five assignees hold 2,048 of 4,851 records between them. New entrants filing straightforward Cr-Ti-Sn ferritic compositions for condensate resistance are filing into a crowded zone; differentiation has to come from a specific alloying twist or a processing route, not the base chemistry.
Filing volume is genuinely cooling, not just lagging
The three-year window from 2021 to 2024 is the last one fully comparable across years, and it shows a real 39% drop from 100 to 61 records. Several of the largest historical filers show zero activity in the latest tracked year, consistent with a maturing composition space rather than a temporary reporting gap.
Claims cluster in metallurgy, not exhaust hardware
Alloy composition (C22C) and heat treatment (C21D) together dominate the classification profile, while exhaust-specific classification (F01N) covers only 7.6% of records. Filers targeting the exhaust assembly itself, rather than the steel grade, face a thinner prior-art layer.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ferritic stainless steel for automotive exhaust, with the prior art for and against each one.
Who holds the ground, and where it is open
The ranked leaders are steelmakers first, with two oilfield-technology assignees appearing in the same corpus due to overlapping alloy and thermal-treatment classification.
A single steelmaker holds a clear volume lead
The leading assignee's 761 records sit well above the fifth-place total of 276, indicating a genuinely dominant single filer rather than a tightly bunched top group.
Steel-automaker pairs signal joint development
The strongest co-assignee pairing links a major steelmaker with a major automaker at 36 shared families, pointing to collaborative alloy qualification programmes rather than arm's-length licensing.
Historic leaders have gone quiet in the latest tracked year
Multiple assignees that built large historical portfolios, including the top-ranked filer, show zero filings in the most recent year with -100% YoY change. Read this alongside the 18-month publication lag before concluding the leaders have exited.
| Assignee | Recent year | YoY |
|---|---|---|
| JFE Steel Corporation | 0 | -100% |
| Nippon Steel & Sumikin Stainless Steel Corp. | 0 | — |
| Nisshin Steel Co., Ltd. | 0 | — |
| Shell Oil Company | 0 | — |
| Nippon Steel Corporation | 0 | -100% |
| Shell Internationale Research Maatschappij B.V. | 0 | — |
| Nippon Steel Stainless Steel Corp. | 0 | — |
| POSCO Co., Ltd. | 0 | -100% |
Where to take this analysis
The landscape points to a mature, concentrated composition layer and a thinner exhaust-hardware and joining layer worth checking claim-by-claim.
Map the white space in exhaust-specific claims
Cross-check candidate compositions against the thinner F01N and B23K classification layers before assuming the core C22C prior art is the only barrier.
Explore white space in Eureka →Track the leading assignees' next moves
Several top filers have gone quiet in the latest year; watching their continuation filings and citations will show whether that is a pause or an exit.
Set up assignee monitoring in Eureka →Common questions on this landscape
The assignee ranking is led by one steelmaker with 761 records, well ahead of the fifth-ranked filer at 276. The top five assignees together account for 2,048 of the 4,851 records in scope, or 42.2% of the field, so filing activity is concentrated among a small group of steel producers rather than spread evenly. Automakers appear mainly through co-assignee filings alongside these steelmakers rather than as independent top filers.
Filing peaked in 2017 at 179 records and has trended down since. The clearest comparable measure is 2021 to 2024, the last window unaffected by publication lag, where filings fell 39% from 100 to 61. Readers should treat 2025 and 2026 figures as still filling in, since publication typically lags actual filing by around eighteen months, but the multi-year decline through 2024 is real.
Records are classified predominantly under C22C (alloys, 63.5% of records) and C21D (heat treatment, 33.4%), meaning most claims concern the steel's composition and processing route rather than the exhaust assembly itself. Exhaust-specific classification under F01N covers only 7.6% of records, and welding/brazing under B23K covers 4.7%. This split suggests the exhaust-hardware and joining layers carry comparatively less claim density than the base alloy chemistry.
This POSCO filing from December 2015 claims a ferritic stainless steel composition tuned for condensate corrosion resistance, moldability and high-temperature oxidation resistance, using tightly specified bands of chromium, titanium, tin and other elements with tin concentrated at the surface. Anyone proposing a similar low-carbon, Ti-stabilised, Sn-surface-segregated composition for exhaust condensate service should check their claim scope against this filing's specific compositional ranges. It is representative of a broader cluster of condensate-corrosion compositions rather than a singular blocking patent.
The composition data points to exhaust-specific hardware claims (F01N, 7.6% of records) and joining processes (B23K, 4.7%) as thinner layers relative to the dominant alloy and heat-treatment classes. Sub-areas such as ridging-resistant grain texturing, dual niobium-titanium stabilisation and thin-gauge formability for manifold applications are not separately broken out in the top-line composition figures but sit adjacent to the dense C22C core. A freedom-to-operate review focused on these narrower branches, rather than base alloy chemistry, is likely to find more room to file.
Research Ferritic Stainless Steel for Automotive Exhaust in depth with Eureka
Go past this page: query the whole ferritic stainless steel for automotive exhaust corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
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.