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This work compares the thermal responses of an α-iron and two carbon steels (C12 and C65 steel) via in-situ infrared thermography under 20 kHz ultrasonic tension-compression fatigue testing. The α-iron has only ferrite phase, and C12 and C65 steels have ferrite-pearlite dual phases. During a series of interrupted self-heating tests, the surface temperature of the three materials increases gradually with stress amplitude, while the relation is non-linear. The increase of carbon content, inducing the pearlite phase percentage increasing, results in a lower temperature increase and higher fatigue strength. For the three materials, at a certain stress amplitude level, the specimen temperature suddenly increases to hundreds of degrees. Moreover, the dissipated energy per cycle is estimated based on the 1D heat diffusion equation and a power function between dissipated energy per cycle and stress amplitude is found. Finally, the mechanisms driving the observed thermal responses are discussed.

International audience; The objective of this work is to improve the knowledge of the shock-to-detonation transition of nitromethane. The study is based on a spectral analysis in the range 0.3–0.85 µm, with a 28-nm resolution, during experiments of plane shock impacts on explosive targets at 8.6 GPa. The time-resolved radiant spectra show that the detonation front, the reaction products produced during the superdetonation, and the detonation products are semitransparent. The temperature and absorption coefficient profiles are determined from the measured spectra by a mathematical inversion method based on the equation of radiative transfer with Rayleigh scattering regime. Shocked nitromethane reaches at least 2500 K, showing the existence of local chemical reactions after shock entrance. Levels of temperature of superdetonation and steady-state detonation are also determined.