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Autori: P.Petculescu, Zagan R., Bormambet M
Editorial: Journal of Optoelectronics and Advanced Materials, vol. 9, no. 12, p.3847-3851, 2007.
In this paper, the authors aim to analyze the influence of thermal treatments on the microstructure of cryogenic material welds. The changing of physical-mechanical and acoustical-spectral parameters is analyzed when a thermal treatment and a thermo-mechanical treatment are applied. These welds are analyzed having as reference the sample B without being
exposed to a thermal treatment that is also the witness sample. One noticed that due to the applied thermal treatment, the weld constituents are composed of austenite + ferrite + Cr carbide precipitate with different volume fractions and different
microstructures (grain sizes). There are shown welds that present a high hardness, a higher transparency of acoustic energy, different resonance frequency and Spectral Peak Ratio (SPR), all these depending on the scope of using the weld.
The experimental measurements presented here were obtained by the direct contact method using silicon gel as the coupling medium with the pulse-echo technique, with a 5MHz transducer (Nortec). The instrumentation consisted of an IPR-
100 signal generator, an A/D-90 converter and SMC-4 step by step motors from Physical Acoustic Corporation. The signals
received at the transducer from the sample were sent to an oscilloscope, where their amplitude and velocity was read directly and to the sampler. Signals from the sampler were transmitted to the spectral analyzer where the spectrum of the
concerned signal was photographed.
Cuvinte cheie: materiale, fizica // materials, physics