A Comparative Assessment Of Cyclic Deformation Behavior Of Sa333 Gr-6 Steel At Ambient And Elevated Temperatures

The aim of this investigation is to study the comparative cyclic deformation behavior of SA333 Gr-6 steel at two different temperatures. Strain-controlled low cycle fatigue experiments were carried out at 1 x 10(-3) s(-1) strain rate at room temperature and 300 degrees C. Cyclic hardening of the steel was observed at both the temperatures. However, greater cyclic hardening was observed at 300 degrees C for all the strain amplitudes. Non-Masing behavior was observed at both the temperatures. Greater deviation from Masing behavior was observed at 300 degrees C due to generation of more dislocation activities. Higher dislocation density and sub-cell structure formation is associated with the hardening characteristic of the material. Lower fatigue lives were observed for all strain amplitudes at 300 degrees C in comparison to room temperature. This is due to the deleterious effect of dynamic strain aging, which is activated at 300 degrees C. The fracture surface reveals that with an increase in strain amplitude the number of crack initiation sites increases and the fatigue region decreases, which leads to a reduction in fatigue life.