Correlation of the high and very high cycle fatigue response of ferrite based steels with strain rate-temperature conditions
TypeArticles dans des revues avec comité de lecture
The discrepancies observed between conventional and ultrasonic fatigue testing are assessed through the mechanisms of dislocation mobility in BCC metals. The existence of a transition condition between thermally-activated and athermal regimes for screw dislocation mobility is studied under fatigue loading based on infrared thermography and microstructural characterization, here in the case of DP600 dual-phase steel. Evidence is obtained regarding the microstructural sources of crack initiation, which is found to be consistent with the existence of a transition in the modes of deformation. From the analysis of the experimental data gathered in this work, guidelines are given regarding the comparison and interpretation of S-N curves obtained from conventional and ultrasonic fatigue testing. The inevitable temperature increases under ultrasonic fatigue at high stress amplitudes along with the rate dependent deformation behavior of ferrite, as a BCC structure, were found as the key parameters explaining the observed fatigue behavior and thermal response under low and ultrasonic frequencies. A transition map was produced using the experimental results for DP600 steel as well as data available in the literature for other ferrite based steels, showing the correlation between thermally-activated screw dislocation movement and the absence of failure in very high cycle fatigue.
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TORABIAN, Noushin; FAVIER, Véronique; ZIAEI-RAD, Saeed; DIRRENBERGER, Justin; ADAMSKI, Frédéric; RANC, Nicolas (Elsevier, 2016)The present work employed in situ infrared thermography to investigate the thermal response and dissipative mechanisms of a dual-phase steel under ultrasonic tension-compression fatigue testing. A classical thermal response ...
Self-Heating Measurements for a Dual-Phase Steel under Ultrasonic Fatigue Loading for stress amplitudes below the conventional fatigue limit TORABIAN, Noushin; FAVIER, Véronique; ZIAEI-RAD, Saeed; ADAMSKI, Frédéric; DIRRENBERGER, Justin; RANC, Nicolas (Elsevier, 2016)The aim of the present research was to study the self-heating behavior of a dual-phase steel under ultrasonic fatigue loading for stress amplitudes lower than the conventional fatigue limit. The steel studied in this ...
Calorimetric Studies and Self-Heating Measurements for a Dual-Phase Steel Under Ultrasonic Fatigue Loading TORABIAN, Noushin; FAVIER, Véronique; ZIAEI-RAD, Saeed; DIRRENBERGER, Justin; ADAMSKI, Frédéric; RANC, Nicolas (ASTM International, 2016)The objective of the present research is to study the self-heating behavior of a dual-phase (DP) steel under ultrasonic fatigue loading and to investigate the effect of frequency on intrinsic heat dissipation of the material. ...
PHUNG, Ngoc-Lam; FAVIER, Véronique; RANC, Nicolas; VALES, Fréderic; MURGHRABI, Haël (ELSEVIER, 2014)The surfaces of commercially pure polycrystalline copper specimens subjected to interrupted 20 kHz fatigue tests in the very high cycle fatigue regime were investigated. The stress amplitude needed to form the early slip ...
PHUNG, Ngoc-Lam; MARTI, Nicolas; BLANCHE, Antoine; RANC, Nicolas; FAVIER, Véronique; CHRYSOCHOOS, André; SAINTIER, Nicolas; GREGORI, Fabienne; BACROIX, Brigitte; THOQUENNE, Guillaume (Elsevier, 2013)The DISFAT project is a French project financially supported by the French National Agency for Research (ANR). It aims at a deeper understanding of mechanisms leading to crack initiation in metals and alloys under Very ...