Heat Treatment of Large Forgings Patents: Who Leads, Where Gaps Are 2026
- Concentrated at the top. The leading assignee alone accounts for 42 of 280 records, and the top 5 combined hold 46.8% of all 280 records in scope.
- Filing has cooled from its peak. 2017 was the peak year at 24 records; from 2021 (4) to 2024 (2), the last complete year, filings fell 50%.
- Heat treatment overlaps alloy design more than surface coating. C21D (heat treatment) and C22C (alloys) each cover roughly half of all 280 records, while C23C (coating) reaches only 10.0%.
Filing growth compares 2021 (4 records) with 2024 (2) — 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 280 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Large forgings fail or succeed on how the heat treatment step manages core cooling rate, quench severity and the residual stress that builds up as thick sections cool unevenly. This landscape tracks patent activity where those variables intersect with furnace charge layout, tempering cycle design and distortion control across steel and alloy forgings used in bearings, shafts, gearing and heavy machinery components.
The 280 records in scope span 2015 through the 2026 cut-off, drawn from filings that claim quench cracking mitigation, through-hardening processes and related residual-stress control methods rather than generic metallurgy.
Filing trends and technology composition
Publication lags filing by roughly 18 months, so counts for 2025 and 2026 will continue to fill in; treat the most recent two years as incomplete rather than as evidence of a slowdown beyond what the 2021-2024 span already shows.
A peak in 2017, then a step down
Filings peaked at 24 records in 2017. The complete-year comparison the dataset supports, 2021 (4 records) to 2024 (2 records), shows a 50% decline over that three-year span.
Heat treatment and alloy classes dominate
C21D (heat treatment of metals) appears on 47.9% of the 280 records and C22C (alloys) on 42.9%, confirming that most filings combine a process claim with a specific alloy composition rather than treating either in isolation. G01L (force and pressure measurement, largely torque and stress sensing) sits at 21.4%, and F16C (shafts, bearings and couplings) at 17.5%, pointing to bearing and shaft applications as the dominant end use. Coating-related C23C reaches only 10.0%, and gearing-specific F16H just 6.4%.
Shares are the percentage of the 280 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Heat Treatment of Large Forgings with Eureka
This page is one run against one query. Ask Eureka your own question about heat treatment of large forgings and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Heat-Treatment Process for a Steel (SKF, filed 2011)
A process for inducing a compressive residual stress in a surface region of a steel component: induction heating followed by quenching to raise surface hardness, then a martensite and/or bainite through-hardening step to obtain the target microstructure.Illustrates the core claim pattern in this landscape: an induction-heating and quench step paired with a defined through-hardening step, rather than a single generic heat-treatment claim.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6047605A | Collarless circularly magnetized torque transducer having two phase shaft and method for measuring torque usi… | 218 |
| 2 | US6553847B2 | Collarless circularly magnetized torque transducer and method for measuring torque using the same | 171 |
| 3 | US4896544A | Magnetoelastic torque transducer | 153 |
| 4 | US6145387A | Collarless circularly magnetized torque transducer and method for measuring torque using same | 147 |
| 5 | US5052232A | Magnetoelastic torque transducer | 113 |
| 6 | US6260423B1 | Collarless circularly magnetized torque transducer and method for measuring torque using same | 104 |
| 7 | US5556348A | Toroidal-type continuously variable transmission | 58 |
| 8 | US6315455B1 | Rolling bearing | 52 |
| 9 | US6423158B1 | Rolling bearings and gear shaft support device | 49 |
| 10 | US3885995A | Process for carburizing high alloy steels | 43 |
Citation counts favour older filings that have had more time to accumulate references within the searched corpus; read them as a signal of influence on the field, not of current commercial importance.
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Three patterns matter more than the raw counts: where citation weight sits, how tightly the leader holds the field, and which application area is actually being claimed.
Citation weight sits on torque-transducer sensing, not on heat treatment itself
The five most-cited records in this landscape are all magnetoelastic or circularly-magnetized torque transducers, with the top record cited 218 times. These are measurement patents that got pulled in because torque and stress sensing on forged shafts is claimed alongside heat treatment steps, not because they are the most active heat-treatment art today.
A single leader holds roughly a sixth of the field on its own
The leading assignee accounts for 42 of the 280 records in scope, and the top 5 combined hold 46.8% of all records. Fifth place already drops to 18 records and tenth place to 7, so the field has one dominant filer sitting above a long tail of 61 ranked companies.
Momentum has stepped down from the 2017 peak
After a peak of 24 records in 2017, filings fell to 4 in 2021 and 2 in 2024, a 50% decline over that complete-year span. Several of the historically active assignees show zero filings in the latest tracked year, which is consistent with a maturing claim set rather than an emerging one.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to heat treatment of large forgings, with the prior art for and against each one.
Assignee concentration and collaboration
61 companies appear in the assignee ranking behind these 280 records. Activity is heavily weighted toward one leader, with co-filing patterns pointing to a small cluster of repeat collaborators.
One assignee outweighs the rest of the ranked list
The top-ranked assignee holds 42 of the 280 records in scope, more than double the fifth-place holder's 18 records. That gap is the clearest single indicator that a large share of the field's foundational claim space is already staked out.
A long tail sits below the top 10
The top 10 assignees combined hold 66.1% of all 280 records, leaving roughly a third of filings spread across the remaining ranked companies. Many of these appear with only one or two records, suggesting narrow, application-specific claims rather than broad process patents.
Co-filing clusters around a small number of repeat pairs
The dataset shows 10 co-assignee pairs, with the strongest links each appearing on 7 shared records. These recurring pairings suggest supplier-partner relationships around specific forging or alloy programmes rather than broad industry-wide joint filing.
| Assignee | Recent year | YoY |
|---|---|---|
| Magna Lastic Devices Inc | 0 | — |
| Nisshin Steel Co., Ltd. | 0 | — |
| Outokumpu Oyj | 0 | — |
| NSK Ltd. | 0 | — |
| MAG DEV | 0 | — |
| JTEKT Corporation | 0 | — |
| AB SKF | 0 | — |
| Toyota Motor Corporation | 0 | — |
Where to take this analysis
The dataset points to a field with concentrated ownership at the top and open branches around sensing and process control below it.
Map the leader's actual claim boundaries
Before filing near the dominant assignee's territory, pull its full claim set rather than relying on record counts alone, since 42 records can still leave narrow gaps in specific alloy or geometry combinations.
Explore assignee claims in EurekaTrack the under-claimed branches
Furnace charge layout and in-process distortion sensing show low filing density relative to the core heat-treatment classes, which is where a well-drafted first claim has the most room to stand.
Run a white space search in EurekaCommon questions on this landscape
One assignee leads the ranked list with 42 of the 280 records in scope, well ahead of the fifth-place holder at 18 records and the tenth-place holder at 7. The top 5 assignees combined hold 46.8% of all 280 records, and the top 10 combined hold 66.1%. Below that, activity spreads thinly across a long tail of the 61 companies that appear in the ranking, many with only one or two filings.
Filing peaked in 2017 at 24 records and has stepped down since. Comparing the two most recent complete years the dataset supports, filings fell from 4 in 2021 to 2 in 2024, a 50% decline over that span. Because publication lags filing by roughly 18 months, the 2025-2026 figures are still incomplete and should not be read as confirming a further drop.
Alloy composition claims (IPC class C22C) appear alongside heat-treatment process claims (C21D) in a large share of the 280 records, at 42.9% and 47.9% respectively, meaning most filings pair a specific alloy with a specific process rather than claiming either alone. Force and pressure measurement (G01L, 21.4%) and shafts, bearings and couplings (F16C, 17.5%) point to torque and stress sensing on bearing or shaft components as the dominant application. Coating (C23C) and gearing (F16H) are present but much smaller, at 10.0% and 6.4%.
US20110073222A1 claims a heat-treatment process for a steel component that combines induction heating and quenching to raise surface hardness with a subsequent martensite and/or bainite through-hardening step. The claim structure ties a specific heating-and-quench sequence to a defined resulting microstructure, rather than claiming heat treatment broadly. Anyone designing a process that induces compressive residual stress through this same induction-heat-then-through-harden sequence on steel forgings should review this record closely before finalising a process claim.
Filing density is lower in branches like furnace charge layout optimisation, in-process distortion sensing, and quench crack prediction modelling compared to the core heat-treatment and alloy classes that cover close to half of all 280 records. These branches sit adjacent to well-claimed territory without being occupied by it, which typically means narrower prior art to design around. A first claim there should tie a specific sensing, layout or predictive method to a measurable process outcome rather than claiming the heat-treatment step itself.
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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.