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Run your analysis now →https://www.patsnap.com/resources/blog/rd-blog/duplex-stainless-steel-fabrication-patent-landscape/ · Patsnap · data cut-off 2026-07-31 · downloaded from the live page
Patent Landscape · Duplex Stainless Steel FabricationDuplex Stainless Steel Fabrication Patents: Who Holds the Claims
- Top five hold half the field. the five leading assignees combine for 531 of 1,070 records in scope (49.6%), with a long tail of single- and few-filing entrants beneath them.
- Filing has plateaued, not fallen. filings held flat from 2021 to 2024 (29 to 29, 0% change) — the apparent drop after 2024 reflects publication lag, not a slowdown.
- Alloys dominate, welding is thinner. C22C alloy claims cover 78.2% of records while B23K welding/brazing claims cover just 12.2%, leaving fabrication-process claims comparatively open.
1,070
Published Records
50%
Top-5 Share of All Records
0%
Filing Growth 2021→2024
EP
Leading Jurisdiction
Filing growth compares 2021 (29 records) with 2024 (29) — 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 1,070 records in scope (CR5), not by the ranked leaders only.
Published byPatsnap Research··7 min readSourced from Patsnap Eureka
Overview
What this landscape covers
Duplex stainless steel fabrication sits at the intersection of alloy chemistry and thermomechanical processing: getting the ferrite-austenite balance right through composition, then holding it through welding and heat treatment without triggering sigma phase precipitation or losing impact toughness. The 1,070 records in this dataset span filings from 2015 through the 2026 cut-off, searched across alloy composition, pitting resistance equivalent, nitrogen alloying, heat input control and welding filler terms together with duplex and super-duplex grade language.
Records are drawn from major receiving offices including the EPO, the United States, India, the WIPO PCT route, China and Australia, giving a cross-jurisdictional view of where duplex steel fabrication claims are actually being filed rather than just where the base alloy patents originate.
Filing activity and technology composition, 2015-2026
Source: Patsnap Eureka. Assignee ranking and totals. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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The Data
Filing trends and technology composition
Two views of the same 1,070 records: how filing activity has moved year over year, and which IPC subclasses carry the claims.
Filing trend: a plateau, not a decline
Filings peaked at 57 in 2017 and have since settled into a lower, steadier band; the 2021-2024 window shows no net change (29 to 29, 0%). Because publication trails filing by roughly 18 months, the thin totals for 2025 and 2026 are an artefact of that lag and should not be read as the technology cooling off.
Technology composition: alloys first, process claims thinner
C22C (alloys) appears in 78.2% of records and C21D (heat treatment) in 31.5%, confirming that composition and post-weld heat treatment carry most of the claim weight. B23K (welding/soldering/brazing) sits at only 12.2%, and B22F (powder metallurgy) at 3.0% — both comparatively under-claimed relative to how central welding practice is to duplex fabrication in the field.
Shares are the percentage of the 1,070 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Source: Patsnap Eureka. Filing trend and technology composition. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.
Go deeper on Duplex Stainless Steel Fabrication with Eureka
This page is one run against one query. Ask Eureka your own question about duplex stainless steel fabrication and every answer comes back with the patent numbers behind it.
Try EurekaKey Patents
Representative and most-cited filings
Representative filing
US20170327923A1 — Super duplex stainless steel with improved yield strength and impact toughness
POSCO
Filed by POSCO, this application controls reduction ratio and heat treatment temperature to produce thick-section (30 mm or greater) super duplex stainless steel with a specified microstructure of ferrite, austenite and secondary austenite phases and a fine grain size, targeting a defined Cr-Ni-Mo-N composition window.Abstract condensed from the original filing; composition and process ranges are as published.
Most-cited records in this landscape
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | JP1993132741A | High strength duplex stainless steel excellent in corrosion resistance | 145 |
| 2 | US5298093A | Duplex stainless steel having improved strength and corrosion resistance | 85 |
| 3 | EP0545753A1 | Duplex stainless steel having improved strength and corrosion resistance | 77 |
| 4 | US7347903B2 | Duplex stainless steel for urea manufacturing plants | 64 |
| 5 | EP2258885A1 | Low-alloy duplex stainless steel wherein weld heat-affected zones have good corrosion resistance and toughness | 63 |
| 6 | US5440090A | Duplex stainless steel welding method | 62 |
| 7 | US5733387A | Duplex stainless steel, and its manufacturing method | 59 |
| 8 | US6042782A | Welding material for stainless steels | 55 |
| 9 | US20160033059A1 | Flowforming corrosion resistant alloy tubes | 50 |
| 10 | WO2005014872A1 | Duplex stainless steel and method for production thereof | 49 |
Citation counts favour older filings in any searched corpus — read them as a signal of influence on later filers, not as a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Source: Patsnap Eureka. Citation counts and representative records. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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What the numbers mean for a filing decision
Three findings that shape where a new duplex steel fabrication filing is likely to land, and where it is likely to collide with dense prior art.
Concentration
49.6%
of 1,070 records held by the top 5 assignees
The field is concentrated but not closed
Roughly half of all records in scope belong to five assignees, and the top ten combine for 62.1% (665 records). That leaves close to 40% of the field spread across a long tail of single-digit and single-filing entrants — room for a well-differentiated composition or process claim, but a crowded space for anything close to the core alloy chemistry.
Basis: assignee ranking, 1,070 records in scope
Momentum
29 → 29
filings, 2021 to 2024 (0% change)
Flat, not falling
The three-year window that can be read as complete shows no net movement in filing volume. Recent-year totals for the largest historical filers show zero activity in the latest year, but that is consistent with the 18-month publication lag across the whole dataset, not a sign the leaders have stopped filing.
Basis: filing trend by year, 2021-2024
Claim balance
78.2% vs 12.2%
C22C alloy share vs B23K welding share
Composition claims crowd out process claims
Alloy composition (C22C) appears in more than three-quarters of records while welding, soldering and brazing (B23K) appears in barely one in eight. Heat treatment (C21D) at 31.5% sits in between. A fabrication-process filing focused on welding procedure rather than alloy design faces a comparatively thinner prior-art field.
Basis: IPC subclass shares of 1,070 records in scope
Eureka AI Agent
Looking for what nobody has claimed yet?
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to duplex stainless steel fabrication, with the prior art for and against each one.
Source: Patsnap Eureka. Co-assignee relationships and derived observations. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Players
Who is filing, and where the claim space is still open
The ranked leaders in this dataset are steelmakers with decades of duplex grade development behind them; the co-filing pattern shows how tightly some of that work is held jointly between parent and subsidiary or research-institute pairs.
Leader
184
records, the single largest assignee
One filer well ahead of the field
The leading assignee holds 184 records, more than four times the count at fifth place (42). That gap suggests a sustained, long-running filing programme rather than a single product push, and it sets the bar any competitor needs to clear to contest the core alloy space directly.
Basis: assignee ranking
Mid-field
42 → 20
records, 5th to 10th place
A sharp drop after the top five
Fifth place holds 42 records and tenth place holds 20 — roughly half — showing the concentration curve steepens quickly outside the leading group. Below tenth, the ranking spreads across a long tail of far smaller filers.
Basis: assignee ranking
Co-filing
10 pairs
co-assignee pairs identified
Joint filing is the exception, not the rule
Only ten co-assignee pairs appear across the dataset, the strongest linking a steelmaker to its plant-engineering partner. Most records in this field are filed by a single assignee, so joint-venture or licensing routes into the space are the exception rather than the norm.
Basis: co-assignee pairs, 1,070 records in scope
Recent filing momentum by assignee
| Assignee | Recent year | YoY |
|---|---|---|
| Outokumpu Oyj | 0 | — |
| Sandvik Intellectual Property AB | 0 | — |
| Nippon Steel Corporation | 0 | -100% |
| Pohang Iron & Steel Co., Ltd. (POSCO) | 0 | — |
| Sumitomo Metal Industries, Ltd. | 0 | — |
| Nippon Steel Stainless Steel Corporation | 0 | — |
| Nippon Steel & Sumikin Stainless Steel Corporation | 0 | — |
| NIPPON STEEL & SUMITOMO METAL CORP | 0 | — |
Source: Patsnap Eureka. Assignee-level momentum. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
What's Next
Where to take this analysis
The dataset points to a concentrated core and a thinner set of adjacent claim areas. The next step is usually to test a specific composition or process idea against the records that actually sit in its path.
Map a candidate claim against the leaders
Run a specific composition window or welding parameter against the records held by the top assignees to see how close prior art actually sits before drafting.
Explore in Patsnap EurekaTrack the under-claimed branches
Powder metallurgy and welding-filler formulation carry noticeably fewer records than the alloy core — worth monitoring for new entrants before the space fills in.
Set up monitoring in Patsnap EurekaSource: Patsnap Eureka. Forward-looking reading of the same dataset. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
FAQ
Common questions about duplex stainless steel fabrication patents
It is moderately concentrated. The five leading assignees in this dataset hold 531 of 1,070 records in scope, or 49.6%, and the top ten combine for 62.1% (665 records). That leaves close to 40% of the field spread across a long tail of smaller filers, so the space is not closed to new entrants, particularly outside the core alloy composition claims held by the largest steelmakers.
Filing volume has been flat rather than growing or shrinking over the most recent complete window: 29 records in 2021 versus 29 in 2024, a 0% change. Totals for 2025 and 2026 look much lower, but that reflects the roughly 18-month lag between filing and publication, not an actual drop in activity. The historical peak in this dataset was 2017, at 57 filings.
Alloy composition claims (IPC class C22C) appear in 78.2% of the 1,070 records in scope, making it by far the densest area. Heat treatment of metals (C21D) follows at 31.5%. Welding, soldering and brazing (B23K) covers only 12.2% of records, and powder metallurgy (B22F) just 3.0%, indicating the fabrication-process side of the field carries comparatively lighter claim density than the underlying alloy chemistry.
It is a POSCO filing for super duplex stainless steel with improved yield strength and impact toughness, aimed at thick sections of 30 mm or greater. The claims control reduction ratio and heat treatment temperature to produce a microstructure with ferrite, austenite and secondary austenite phases at a fine grain size, within a defined chromium, nickel, molybdenum and nitrogen composition window. Anyone targeting thick-section super duplex plate with a similar composition and heat treatment approach should check this filing's specific ranges before drafting around it.
The comparatively thinner IPC classes point to it: welding filler formulation and heat input control during multi-pass welding (B23K at 12.2% of records), powder metallurgy routes to duplex grades (B22F at 3.0%), and layered or clad duplex laminates (B32B at 3.8%) all carry noticeably fewer records than the alloy composition core. These are the branches worth checking first for a claim that does not immediately collide with the leading assignees' core chemistry patents.
Answers are grounded in the same dataset. Derived from a Patsnap search on Duplex Stainless Steel Fabrication covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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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.