C21D 9/04
Heat treatment: for rails
Official title: for rails
C21D9/04 (Heat treatment: for rails) appears on 172 US grants and 179 published applications in this corpus.
Search patents in C21D- Granted patents
- 172
- Published applications
- 179
- Assignees
- 104
- Inventors
- 395
- Latest grant
- 29 Sep 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1977 | 1 | 0 |
| 1978 | 2 | 0 |
| 1979 | 0 | 0 |
| 1980 | 3 | 0 |
| 1981 | 0 | 0 |
| 1982 | 0 | 0 |
| 1983 | 1 | 0 |
| 1984 | 4 | 0 |
| 1985 | 1 | 0 |
| 1986 | 2 | 0 |
| 1987 | 3 | 0 |
| 1988 | 2 | 0 |
| 1989 | 3 | 0 |
| 1990 | 6 | 0 |
| 1991 | 3 | 0 |
| 1992 | 1 | 0 |
| 1993 | 3 | 0 |
| 1994 | 2 | 0 |
| 1995 | 2 | 0 |
| 1996 | 2 | 0 |
| 1997 | 2 | 0 |
| 1998 | 4 | 0 |
| 1999 | 3 | 0 |
| 2000 | 2 | 0 |
| 2001 | 4 | 3 |
| 2002 | 5 | 3 |
| 2003 | 1 | 3 |
| 2004 | 3 | 6 |
| 2005 | 0 | 0 |
| 2006 | 3 | 1 |
| 2007 | 2 | 2 |
| 2008 | 1 | 4 |
| 2009 | 1 | 5 |
| 2010 | 2 | 8 |
| 2011 | 2 | 8 |
| 2012 | 4 | 10 |
| 2013 | 9 | 4 |
| 2014 | 6 | 9 |
| 2015 | 4 | 16 |
| 2016 | 8 | 7 |
| 2017 | 8 | 12 |
| 2018 | 7 | 12 |
| 2019 | 8 | 15 |
| 2020 | 11 | 11 |
| 2021 | 5 | 7 |
| 2022 | 6 | 9 |
| 2023 | 3 | 4 |
| 2024 | 2 | 6 |
| 2025 | 11 | 5 |
| 2026 | 4 | 9 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
Recent patents
- Welded rail29 Sep 2026US 12,747,483 B2Nippon Steel Corporation
- Track part and method for producing a track part24 Mar 2026US 12,584,184 B2voestalpine Schienen GmbH
- Method of making a tee rail having a high strength base24 Feb 2026US 12,559,812 B2ArcelorMittal
- Overhead rail and trolley system3 Feb 2026US 12,539,898 B2Pellerin Milnor Corporation
- Firmware-based out-of-order command scheduler23 Dec 2025US 12,503,741 B2BAE Systems Information and Electronic Systems Integration Inc.
- Method for Producing a Rail for Railway Infrastructure10 Sep 2026US 2026/0265854 A1voestalpine Rail Technology GmbH
- Rail and method of producing same20 Aug 2026US 2026/0242910 A1Jfe Steel Corporation
- Overhead rail and trolley system6 Aug 2026US 2026/0225628 A1Pellerin Milnor Corporation
- Method and device for welding components, which can be travelled upon, of a track by flash butt welding23 Jul 2026US 2026/0208283 A1Voestalpine Railway Systems GmbH
- Method for increasing hardened layer thickness of a rail head of a flash welded joint of a steel rail and a steel rail16 Jul 2026US 2026/0200019 A1Chengdu Advanced Metal Materials Industry Technology Research Institute Co., Ltd.
Most cited
By later US patents
- Method for the production of improved railway rails by accelerated cooling in line with the production rolling mill35US 4,486,248 AThe Algoma Steel Corporation, Limited · 1984
- Rails of pearlitic steel with high wear resistance and toughness and their manufacturing methods25US 5,658,400 ANippon Steel Corporation · 1997
- Pearlitic steel rail having excellent wear resistance and method of producing the same22US 5,762,723 ANippon Steel Corporation · 1998
- Process for the heat treatment of steel20US 4,082,577 AFried. Krupp Huttenwerke AG · 1978
- Method for manufacturing high strength rail of excellent weldability17US 4,375,995 ANippon Steel Corporation · 1983