The IF Spectrum of Fe-C-N and Fe-17%Cr-C-N Alloys Measured by the Impulse Excitation Technique

Abstract

The temperature dependence of the dynamic Young’s modulus, E, and the damping, Q-1, of Fe-C-N and Fe-17%Cr-C-N alloys with different C, N contents were studied in the temperature range of 25°C to 600°C by the impulse excitation internal friction technique at 1KHz. Hot rolled samples were cold rolled to a thickness of 1.2mm and recrystallization annealed at 820°C for 30sec then gas jet cooled (-50°C/sec). Samples were subsequently tensile strained 6% and 16%. A Snoek peak was observed at 120°C in the undeformed sample and a Snoek-Koster peak was observed at 400°C after deformation. In the case of the Fe-Cr-C-N alloy, a high damping background due to magneto-mechanical damping was observed in the temperature range of 25°C to 400°C. A broaden Snoek peak in FeCr was observed at 300°C. The internal friction peaks observed in this study showed the strong dependence of the amount of interstitial contents and deformation and were well correlated to previous internal friction studies measured mainly by torsion pendulum and inverted torsion pendulum.

Relationship Between Bake Hardening, Snoek-Köster and Dislocation-Enhanced Snoek Peaks in Coarse Grained Low Carbon Steel

“…4d-f). The internal friction spectra are comprised of: (1) carbon Snoek peak [7,[36][37][38][39][40][41], (2) the dislocation-enhanced Snoek peak [27,[51][52][53][54][55][56][57][58][64][65][66][67][68], and (3) Snoek-Köster peak [69][70][71][72][73][74][75][76][77], and typical exponential hightemperature background [70,[75][76][77]. resolved internal friction peaks, obtained after background subtraction, are illustrated in fig.…”

“…It should be emphasized, however, that the experimental results reported by jung show large dispersion in internal friction data estimated from free decaying oscillations. Such a high dispersion in internal friction is a characteristic feature of the impulse internal friction technique for high values of internal friction [27,67].…”

“…Dislocation-enhanced Snoek peak was discovered by Magalas et al [51]. The existence of the dislocation-enhanced Snoek peak was confirmed in highpurity fe-C alloys in 2006 [58] in resonant low-frequency internal friction measurements [7][8][9]35,[59][60][61][62][63][88][89][90] and by De Cooman and co-workers using the resonant impulse excitation internal friction technique operating at higher frequencies [27,[64][65][66][67][68]. The presence of the dislocation-enhanced Snoek peak and Snoek-Köster peak was also reported by jung et al [27] in commercial ultra-low carbon bake-hardenable steels.…”