Patent US3948688A successfully refreshed from Google Patents.
US3948688A
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Martensitic alloy conditioning
Assignee: Texas Instruments Inc
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Filing: 1975-02-28
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Granted: 1976-04-06
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Expires: 1995-02-28
Abstract
Abstract A two-stage process for conditioning an annealed martensitic alloy of titanium and nickel to improve its service life and provide enhanced elongation activity under high operating stress. In the first stage of the process, the alloy is maintained under a tensile stress sufficient to strain it beyond its plastic yield point while it is repeatedly thermally cycled in a primary temperature range between a lower temperature limit below the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit at least about equal to the temperature at which essentially all the martensite is converted to austenite on heating. In the second stage of the process, the alloy is maintained at a tensile stress sufficient to strain it beyond its plastic yield point while it is repeatedly thermally cycled in a secondary temperature range between a lower temperature limit equal to or higher than the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit equal to or lower than the temperature at which conversion of austenite to martensite commences on cooling. A novel product having enhanced service life and elongation activity is obtained.
Inventors
- 👤 Joel P. Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:41
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/10; C22F1/006
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
174 words
A process for conditioning an annealed martensitic alloy of titanium and nickel to improve its service life and provide enhanced elongation activity under high operating stress, the process comprising the steps of: maintaining the alloy under a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a primary temperature range between a lower temperature limit below the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit at least about equal to the temperature at which essentially all the martensite is converted to austenite on heating; and thereafter maintaining the alloy at a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a secondary temperature range between a lower temperature limit equal to or higher than the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit equal to or lower than the temperature at which conversion of austenite to martensite commences on cooling.
Claim 2
Dependent Claim
174 words
A process for conditioning an annealed martensitic alloy of titanium and nickel to improve its service life and provide enhanced elongation activity under high operating stress, the process comprising the steps of: maintaining the alloy under a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a primary temperature range between a lower temperature limit below the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit at least about equal to the temperature at which essentially all the martensite is converted to austenite on heating; and thereafter maintaining the alloy at a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a secondary temperature range between a lower temperature limit equal to or higher than the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit equal to or lower than the temperature at which conversion of austenite to martensite commences on cooling.
Claim 3
Dependent Claim
44 words
A process as set forth in claim 1 wherein the difference between the lower temperature limit and the upper temperature limit in said secondary range is sufficient that at least 25% by volume of the alloy is subjected to austenite/martensite conversion in each cycle.
Claim 4
Dependent Claim
22 words
A process as set forth in claim 1 wherein said alloy comprises approximately 54.3% by weight nickel and the balance essentially titanium.
Claim 5
Dependent Claim
32 words
A process as set forth in claim 3 wherein said alloy is tension-annealed prior to conditioning and is maintained under a tensile stress of at least about 180,000 psi during thermal cycling.
Claim 6
Dependent Claim
32 words
A process as set forth in claim 4 wherein the alloy is in the form of a wire which is thermally cycled by subjecting it to alternate resistance heating and ambient cooling.
Claim 7
Dependent Claim
26 words
A process as set forth in claim 5 wherein the alloy is thermally cycled in said secondary temperature range by application of square wave current pulses.
Claim 8
Dependent Claim
34 words
A process as set forth in claim 6 wherein the ON time of the current pulse is between about 0.1 and 0.5 seconds and the OFF time is between about 0.1 and 0.5 seconds.
Claim 9
Dependent Claim
53 words
A process as set forth in claim 7 wherein the wire has a diameter on the order of 0.002 in. and is subjected to square wave current pulses with an average maximum current of about 65 ma with an ON time of approximately 0.25 seconds and an OFF time of approximately 0.25 seconds.
Claim 10
Dependent Claim
49 words
A process as set forth in claim 1 wherein the alloy is in the form of a wire and is subjected to tensile stress by connecting it to a fixed restraint at one point along its length and loading it with a spring at another point along its length.
Claim 11
Dependent Claim
166 words
An annealed martensitic alloy of titanium and nickel having an extended service life and high elongation activity under high operating stress prepared by: maintaining the annealed alloy under a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a primary temperature range between a lower temperature limit below the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit at least about equal to the temperature at which essentially all the martensite is converted to austenite on heating; and thereafter maintaining the alloy at a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a secondary temperature range between a lower temperature limit equal to or higher than the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit equal to or lower than the temperature at which conversion of austenite to martensite commences on cooling.
Claim 12
Dependent Claim
166 words
An annealed martensitic alloy of titanium and nickel having an extended service life and high elongation activity under high operating stress prepared by: maintaining the annealed alloy under a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a primary temperature range between a lower temperature limit below the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit at least about equal to the temperature at which essentially all the martensite is converted to austenite on heating; and thereafter maintaining the alloy at a tensile stress sufficient to strain it beyond its plastic yield point while repeatedly thermally cycling the alloy in a secondary temperature range between a lower temperature limit equal to or higher than the temperature at which conversion of martensite to austenite commences on heating and an upper temperature limit equal to or lower than the temperature at which conversion of austenite to martensite commences on cooling.
References Cited (Backward Citations)
US3748197A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-06 | 1979-10-06 | 1980-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-06 | 1983-10-06 | 1984-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-06 | 1987-10-06 | 1988-04-06 | $7700.00 | Window Closed / Lapsed |