Comparison of recrystallisation kinetics determined by stress relaxation, double hit, optical metallography and EBSD approaches

A comparison of the recrystallisation kinetics determined by stress relaxation (SR), double-hit (DH), optical metallography and scanning electron microscope/electron backscattered diffraction (SEM/EBSD) mapping experimental approaches has been conducted. Two different types of steel were used as experimental material: C–Mn and interstitial-free (IF). Tests were carried out in the austenitic region for C–Mn steel and just above the Ar1 temperature for IF steel. Both steels were investigated in static and postdynamic recrystallisation (SRx and PDRx, respectively) regions. The work indicates that some differences exist between the results given by these methods. The biggest correction to the experimental results in the SRx region has to be performed on the “raw data” obtained by the SR method. The SR method, owing to its continually applied stress, tends to accelerate the recrystallisation kinetics. The estimation of the recrystallised fraction in the PDRx region by the DH test gives even higher error because of dynamic changes of microstructure during the second hit.