US5595706A
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Aluminum containing iron-base alloys useful as electrical resistance heating elements
Assignee: Philip Morris USA Inc
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Filing: 1994-12-29
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Granted: 1997-01-21
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Expires: 2014-12-29
Abstract
Abstract The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have a disordered body centered cubic structure and improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, 4 to 9.5% Al, 0.2-2.0% Ti, 0.5-2% Mo, 0.1 to 0.8% Zr, 0.01-0.5% C, balance Fe.
Inventors
- 👤 Vinod K. Sikka
- 👤 Seetharama C. Deevi
- 👤 Grier S. Fleischhauer
- 👤 Mohammad R. Hajaligol
- 👤 A. Clifton Lilly, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:11
CPC Classifications
C; C22; C22C; C22C33/00; C22C33/02; C22C33/0257; C22C33/0278; C22C38/00; C22C38/06; B; B22; B22F; B22F2998/00; B22F2998/10; B22F2999/00
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
60 words
An iron-based alloy useful as an electrical resistance heating element and having a disordered body centered cubic structure, the alloy having improved room temperature ductility, resistance to cyclic oxidation, thermal fatigue resistance, electrical resistivity and high temperature sag resistance, and comprising, in weight %, 4 to 9.5% Al, 0.5-2.0% Ti, 0.5-2% Mo, 0.1 to 0.8% Zr, 0.01-0.5% C, balance Fe.
Claim 2
Dependent Claim
60 words
An iron-based alloy useful as an electrical resistance heating element and having a disordered body centered cubic structure, the alloy having improved room temperature ductility, resistance to cyclic oxidation, thermal fatigue resistance, electrical resistivity and high temperature sag resistance, and comprising, in weight %, 4 to 9.5% Al, 0.5-2.0% Ti, 0.5-2% Mo, 0.1 to 0.8% Zr, 0.01-0.5% C, balance Fe.
Claim 3
Dependent Claim
11 words
The iron-based alloy of claim 1, wherein the alloy is Ni-free.
Claim 4
Dependent Claim
15 words
The iron-based alloy of claim 1, wherein the alloy has a microstructure which is austenite-free.
Claim 5
Dependent Claim
14 words
The iron-based alloy of claim 1, wherein the alloy has an entirely ferritic microstructure.
Claim 6
Dependent Claim
14 words
The iron-based alloy of claim 1, wherein the alloy is free of ceramic particles.
Claim 7
Dependent Claim
23 words
The iron-based alloy of claim 1, wherein the alloy includes ≦2% Si, ≦30% Ni, ≦0.5% Y, ≦0.1% B, ≦1% Nb and ≦1% Ta.
Claim 8
Dependent Claim
24 words
The iron-based alloy of claim 1, wherein the alloy consists essentially of 8.0-9.0% Al, 0.75-1.5% Ti, 0.75-1.5% Mo, 0.15-0.75% Zr, 0.05-0.35% C, balance Fe.
Claim 9
Dependent Claim
28 words
The iron-based alloy of claim 1, wherein the alloy consists essentially of 8.0-9.0% Al, 0.75-1.25% Ti, 0.75-1.25% Mo, 0.2 to 0.6% Zr, 0.03-0.09% C, 0.01-0.1% Y, balance Fe.
Claim 10
Dependent Claim
31 words
The iron-based alloy of claim 1, wherein the alloy consists essentially of 8.0-9.0% Al, 0.75-1.25% Ti, 0.75-1.25% Mo, 0.1-0.3% Zr, 0.01-0.1% C, 0.25-0.75% Nb, 0.25-0.75% Ta and 0.01-0.1% Y, balance Fe.
Claim 11
Dependent Claim
27 words
The iron-based alloy of claim 1, wherein the alloy consists essentially of 8.0-9.0% Al, 0.75-1.25% Ti, 0.75-1.25% Mo, 0.5-0.75% Zr, 0.05-0.15% C and 0.01-0.2% Si, balance Fe.
Claim 12
Dependent Claim
27 words
The iron-based alloy of claim 1, wherein the alloy consists essentially of 8.0-9.0% Al, 0.05-0.15% Si, 0.75-1.25% Ti, 0.75-1.25% Mo, 0.1-0.3% Zr and 0.2-0.4% C, balance Fe.
Claim 13
Dependent Claim
23 words
The iron-based alloy of claim 1, wherein the alloy comprises an electrical resistance heating element having a room temperature resistivity of 80-400 μΩ·cm.
Claim 14
Dependent Claim
17 words
The iron-based alloy of claim 1, wherein the alloy exhibits room temperature ductility of at least 3%.
Claim 15
Dependent Claim
35 words
The iron-based alloy of claim 1, wherein the alloy heats to 900° C. in less than 1 second when a voltage up to 10 volts and up to 6 amps is passed through the alloy.
Claim 16
Dependent Claim
27 words
The iron-based alloy of claim 1, wherein the alloy exhibits a weight gain of less than 4% when heated in air to 1000° C. for three hours.
Claim 17
Dependent Claim
26 words
The iron-based alloy of claim 1, wherein the alloy has a resistance of 0.05 to 7 ohms throughout a heating cycle between ambient and 900° C.
Claim 18
Dependent Claim
26 words
The iron-based alloy of claim 1, wherein the alloy has a resistivity of 80 to 200 Ω·cm throughout a heating cycle between ambient and 900° C.
Claim 19
Dependent Claim
20 words
The iron-based alloy of claim 1, wherein the alloy exhibits a room temperature reduction in area of at least 14%.
Claim 20
Dependent Claim
18 words
The iron-based alloy of claim 1, wherein the alloy exhibits a room temperature elongation of at least 15%.
Claim 21
Dependent Claim
20 words
The iron-based alloy of claim 1, wherein the alloy exhibits a room temperature yield strength of at least 50 ksi.
Claim 22
Dependent Claim
20 words
The iron-based alloy of claim 1, wherein the alloy exhibits a room temperature tensile strength of at least 80 ksi.
Claim 23
Dependent Claim
23 words
The iron-based alloy of claim 1, wherein the alloy exhibits a high temperature reduction in area at 800° C. of at least 30%.
Claim 24
Dependent Claim
21 words
The iron-based alloy of claim 1, wherein the alloy exhibits a high temperature elongation at 800° C. of at least 30%.
Claim 25
Dependent Claim
23 words
The iron-based alloy of claim 1, wherein the alloy exhibits a high temperature yield strength at 800° C. of at least 7 ksi.
Claim 26
Dependent Claim
23 words
The iron-based alloy of claim 1, wherein the alloy exhibits a high temperature tensile strength at 800° C. of at least 10 ksi.
Claim 27
Dependent Claim
37 words
The iron-based alloy of claim 1, wherein the alloy exhibits thermal fatigue resistance of over 10,000 cycles without breaking when heated from room temperature to 1000° C. for 0.5 to 5 seconds in each of the cycles.
Claim 28
Dependent Claim
11 words
The iron-based alloy of claim 1, wherein the alloy is Cr-free.
Claim 29
Dependent Claim
13 words
The iron-based alloy of claim 1, wherein the alloy is Mn-free and/or Si-free.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-01-21 | 2000-07-22 | 2001-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-21 | 2004-07-22 | 2005-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-21 | 2008-07-22 | 2009-01-21 | $7700.00 | Window Closed / Lapsed |