C21D 9/00
Heat treatment
Official title: Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
C21D9/00 (Heat treatment) appears on 8,598 US grants and 10,399 published applications in this corpus.
Search patents in C21D- Granted patents
- 8,598
- Published applications
- 10,399
- Assignees
- 2,673
- Inventors
- 17,097
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 56 | 0 |
| 1977 | 66 | 0 |
| 1978 | 62 | 0 |
| 1979 | 51 | 0 |
| 1980 | 65 | 0 |
| 1981 | 60 | 0 |
| 1982 | 63 | 0 |
| 1983 | 77 | 0 |
| 1984 | 82 | 0 |
| 1985 | 80 | 0 |
| 1986 | 95 | 0 |
| 1987 | 73 | 0 |
| 1988 | 100 | 0 |
| 1989 | 96 | 0 |
| 1990 | 74 | 0 |
| 1991 | 77 | 0 |
| 1992 | 65 | 0 |
| 1993 | 85 | 0 |
| 1994 | 71 | 0 |
| 1995 | 90 | 0 |
| 1996 | 77 | 0 |
| 1997 | 83 | 0 |
| 1998 | 98 | 0 |
| 1999 | 101 | 0 |
| 2000 | 120 | 0 |
| 2001 | 106 | 30 |
| 2002 | 121 | 91 |
| 2003 | 106 | 107 |
| 2004 | 86 | 154 |
| 2005 | 72 | 107 |
| 2006 | 52 | 127 |
| 2007 | 46 | 145 |
| 2008 | 63 | 186 |
| 2009 | 76 | 272 |
| 2010 | 108 | 276 |
| 2011 | 138 | 267 |
| 2012 | 148 | 309 |
| 2013 | 183 | 362 |
| 2014 | 203 | 414 |
| 2015 | 218 | 552 |
| 2016 | 257 | 626 |
| 2017 | 380 | 635 |
| 2018 | 404 | 603 |
| 2019 | 509 | 639 |
| 2020 | 483 | 653 |
| 2021 | 468 | 577 |
| 2022 | 529 | 750 |
| 2023 | 431 | 703 |
| 2024 | 483 | 703 |
| 2025 | 574 | 576 |
| 2026 | 387 | 535 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- C21D 9/46Heat treatment: for sheet metals3,020
- C21D 9/52Heat treatment: for wires1,640
- C21D 9/08Heat treatment: for tubular bodies or pipes957
- C21D 9/0068Heat treatment: for particular articles not mentioned below922
- C21D 9/50Heat treatment: for welded joints583
- C21D 9/40Heat treatment: for rings418
- C21D 9/0006Details, accessories not peculiar to any of the following furnaces401
- C21D 9/32Heat treatment: for gear wheels, worm wheels, or the like316
All 34 subgroupsShow fewer
- C21D 9/0081Heat treatment: for slabs214
- C21D 9/02Heat treatment: for springs195
- C21D 9/0062Heat-treating apparatus with a cooling or quenching zone194
- C21D 9/04Heat treatment: for rails172
- C21D 9/30Heat treatment: for crankshafts154
- C21D 9/0075Heat treatment: for rods of limited length118
- C21D 9/28Heat treatment: for plain shafts118
- C21D 9/38Heat treatment: for roll bodies107
- C21D 9/0093Heat treatment: for screws105
- C21D 9/22Heat treatment: for drills104
- C21D 9/36Heat treatment: for balls92
- C21D 9/0056Furnaces through which the charge is moved in a horizontal straight path86
- C21D 9/34Heat treatment: for tyres52
- C21D 9/18Heat treatment: for knives, scythes, scissors, or like hand cutting tools47
- C21D 9/0087Heat treatment: for chains, for chain links40
- C21D 9/70Furnaces for ingots, i.e. soaking pits36
- C21D 9/0037Rotary furnaces with vertical axis35
- C21D 9/005Furnaces in which the charge is moving up or down35
- C21D 9/42Heat treatment: for armour plate32
- C21D 9/26Heat treatment: for needles31
- C21D 9/24Heat treatment: for saw blades29
- C21D 9/0043Muffle furnaces28
- C21D 9/16Heat treatment: for explosive shells22
- C21D 9/0031Rotary furnaces with horizontal or slightly inclined axis16
- C21D 9/20Heat treatment: for blades for skates6
- C21D 9/44Heat treatment: for equipment for lining mine shafts6
Recent patents
- Housing of an induction hardening tool6 Oct 2026US 12,752,288 B2Aktiebolaget Skf
- Forged steel roll for cold rolling6 Oct 2026US 12,752,325 B2Nippon Steel Corporation
- Workpiece holding device6 Oct 2026US 12,753,453 B2Aktiebolaget Skf
- High strength steel sheet and method of producing same6 Oct 2026US 12,753,454 B2Jfe Steel Corporation
- Ultra-high strength cold rolled steel sheet having excellent bendability, and method of manufacturing same6 Oct 2026US 12,753,455 B2Posco
- Blank, production method for structural member and structural member8 Oct 2026US 2026/0307133 A1Nippon Steel Corporation
- A cold rolled martensitic steel and a method of martensitic steel thereof8 Oct 2026US 2026/0308706 A1
- Non-oriented electrical steel plate with high magnetic induction and manufacturing method thereof8 Oct 2026US 2026/0308707 A1Baoshan Iron & Steel Co., Ltd.
- Steel plate and method for manufacturing same8 Oct 2026US 2026/0308708 A1Posco
- Martensitic stainless steel strip8 Oct 2026US 2026/0308709 A1Proterial, Ltd.
Most cited
By later US patents
- Method for annealing stapler anvils1,469US 5,173,133 AUnited States Surgical Corporation · 1992
- Surface hardening of cams of motor-vehicle camshafts1,402US 4,312,685 AAudi NSU Auto Union Aktiengesellschaft · 1982
- Systems for percutaneous bone and spinal stabilization, fixation and repair1,069US 6,127,597 ADiscoTech N.V. · 2000
- Method of making iron golf clubs with flexible impact surface459US 4,398,965 APepsiCo, Inc. · 1983
- Heat treatment with an autoregulating heater259US 4,623,401 AMetcal, Inc. · 1986