PlainPatent

CPC technology class · C21

C21B - Manufacture OF IRON OR Steel

Manufacture of iron or steel. 713 US utility patents granted 2015–2025, with the leading assignees and year-by-year filing trajectory.

713
US patents granted
C21
Parent CPC class
20
Active assignees
-8%
5-yr velocity

The verdict

Manufacture OF IRON OR Steel ranks #497 of 670 CPC technology areas - 713 US patents granted since 2015, with filing down 8% over five years.

#497
of 670 CPC technology areas
713
US patents granted, 2015–2025
Paul Wurth
leading assignee (45)
-8%
filing velocity, last 5 yrs
Top assignee: PAUL Wurth S.a. (45 patents)

CPC subclass C21B - MANUFACTURE OF IRON OR STEEL - covers 713 US utility patents granted between 2015 and 2025 according to USPTO PatentsView records, within the broader CPC class C21 (METALLURGY OF IRON). See our CPC classification guide for how the system works.

The competitive landscape in C21B is shaped by 20 distinct companies actively filing in this space. PAUL Wurth S.a. leads with 45 patents, followed by Midrex Technologies, Inc. at 30 grants and Primetals Technologies Austria Gmbh at 28.

Filing activity in C21B is down 8% over the past five years versus 2015-2019, a relatively steady filing pace. All counts come directly from USPTO PatentsView and reflect US granted utility patents only.

Is C21B innovation accelerating?

US utility-patent grants per year in C21B, 2015–2025 - recent five years are down 8% versus 2015–2019.

30405060708090 20152016201720182019202020212022202320242025 70

Who leads C21B?

The 12 most active assignees in MANUFACTURE OF IRON OR STEEL - wider bars mean more grants

patents

What this shows Paul Wurth is the most active filer in C21B, holding 45 of the 713 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass C21B
Rank Company Patents in C21B
#1 PAUL Wurth S.a. 45
#2 Midrex Technologies, Inc. 30
#3 Primetals Technologies Austria Gmbh 28
#4 Carbon Technology Holdings, Llc 25
#5 Danieli & C. Officine Meccaniche S.p.a. 15
#6 Tata Steel Limited 13
#7 Suncoke Technology AND Development Llc 11
#8 HYL Technologies, S.a. DE C.v. 10
#9 Technological Resources PTY Limited 9
#10 Siemens VAI Metals Technologies Gmbh 7
#11 Outotec (finland) OY 5
#12 TATA Steel Nederland Technology B.v. 5
#13 Tenova S.p.a. 5
#14 Berry Metal Company 5
#15 Orbite Technologies Inc. 5
#16 Techemet, Lp 5
#17 Macrae Technologies, Inc. 5
#18 Nucor Corporation 4
#19 Nisshin Steel Co., Ltd. 4
#20 Refractory Intellectual Property Gmbh & Co. KG 4

About This Class

CPC subclass C21B belongs to class C21.

713 patents were granted in this class between 2015 and 2025.

20 companies actively patent in this space.

Classification System

Cooperative Patent Classification (CPC) is a hierarchical patent classification system used by the USPTO and EPO.

← All Technology Classes Technology Rankings →

Footprint here vs. claim strategy

Each dot is a leading C21B assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 C21B assignees by class footprint. Bubble size = patents in C21B. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Top 14 C21B assignees by class footprint. Bubble size = patents in C21B. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 10121416182022 01020304050 Patents in C21B Avg claims / patent (company-wide) Paul WurthMidrexPrimetals AustriaCarbon Technology Hol…Danieli & C Officine…Tata SteelSuncoke Technology An…Hyl De C VTechnological Resourc…Siemens Vai MetalsOutotec (Finland) OyTata Steel Nederland…Tenova S P ABerry Metal
Top 14 C21B assignees by class footprint. Bubble size = patents in C21B. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Frequently Asked Questions

What is CPC class C21B?
CPC subclass C21B covers MANUFACTURE OF IRON OR STEEL. It belongs to CPC class C21 (METALLURGY OF IRON), with 713 US utility patents granted since 2015.
How many patents have been filed in C21B?
713 US utility patents were granted in CPC subclass C21B between 2015 and 2025, based on USPTO PatentsView data.
Which company holds the most patents in C21B?
PAUL Wurth S.a. leads C21B with 45 patents, making it the most active assignee in this technology area.
How is patent data for C21B collected?
Patent data comes from USPTO PatentsView, a public research dataset maintained by the United States Patent and Trademark Office. It covers all US granted utility patents and assigns CPC codes based on the technology described in each patent.
What is the difference between CPC class and subclass?
A CPC class (e.g., C21) is a broad technology category. Subclasses like C21B provide finer granularity within that category. PlainPatent organizes data at the subclass level (4-character codes) for the most useful view of technology domains.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from USPTO PatentsView - official U.S. government patent data. See our methodology for computation details. Retrieved and formatted by PlainPatent Editorial

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.