Papers by Author: Sasan Yazdania

Abstract: Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5 GPa and high uniform elongation have been developed in the recent decade. To accelerate the bainitic transformation in theses steels, new chemical composition was designed by MUCG83 thermodynamic model which was developed in Cambridge University by Bhadeshia. The samples, prepared from the hot rolled ingots, were transformed isothermally at the temperature range of 200 to 300°C for different times. The microstructure and mechanical properties of the samples were evaluated by XRD, SEM, hardness and tensile tests. The results showed a unique microstructure and good mechanical properties like other bainitic steels, while the needed time for the completion of transformation is shorter compared to that of others.

Abstract: Effects of tempering temperature and shot peening on fatigue behavior of SAE 1045 steel are reported. Tensile and fatigue property measurements are reported for samples tempered and shot peened at 300 and 550°C. Microstructural studies and fracture surface observations were carried out by optical and scanning electron microscopes. The experimental results showed that, fatigue strength increases with decrease of tempering temperature and shot peening treatment. SEM analyses indicated that all three stages of fatigue fracture affected by tempering treatment whilst shot peening treatment only have an effect on the crack initiation stage.