Measuring and testing – Gas content of a liquid or a solid – By vibration
Patent
1975-09-08
1977-04-26
Goldstein, Herbert
Measuring and testing
Gas content of a liquid or a solid
By vibration
73359R, 324 51, 340253W, G01N 2572, G01R 3100, G08B 2100
Patent
active
040193640
ABSTRACT:
To test certain structural characteristics of a weld formed between two dissimilar metals in order to test the quality, or structural integrity, of the weld, the emf generated at the weld bond interface during welding, as a result of the Seebeck effect (thermocouple), is monitored. As the weld cools, the emf decreases at a first essentially rapid rate with respect to time until the weld begins to recrystallize, or fuse, at which point the emf decreases at a second and slower rate since the latent heat of fusion of the metals decreases the cooling rate of the weld. When recrystallization is complete, the emf decreases at an essentially exponential rate. It has been discovered the rate of change of the emf with respect to time during recrystallization is an indication of the quantity of the metal involved in the weld where the weld is exposed to a constant heat sink, such as the atmosphere, since the more metal that is involved in the weld the slower the weld will cool during fusion, and vice versa. The quantity of metal involved in the weld is indicative of the quality, or structural integrity, of the weld, since the more metal that is involved in the weld the greater the likelihood that a secure weld has been formed. The rate of change of the emf with respect to time during fusion is compared with a predetermined rate of emf change with respect to time which is indicative of a predetermined weld mass of the metals to obtain one indication of the quality of the weld. Further, the occurrence of any discontinuity in the emf during cooling of the weld is detected, and indicates the development of a crack or a venting gas bubble at the weld bond interface, either of which decreases the integrity of the weld.
REFERENCES:
patent: 3406272 (1968-10-01), Ehrlich
patent: 3409755 (1968-11-01), Munro
patent: 3756067 (1973-09-01), Cushman
patent: 3821562 (1974-06-01), Davis et al.
patent: 3829849 (1974-08-01), Stauffer
patent: 3873830 (1975-03-01), Foster
patent: 3930159 (1975-12-01), Marquet
Condra et al., "Thin Film Thermocouple" in Western Electric Technical Digest No. 32, 10/73.
Bergum K. R.
Goldstein Herbert
Miller R. P.
Western Electric Company Inc.
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