The aim of this study was evaluation of microstructure variations in AISI 316 stainless steel during hot rolling. On condition that in the first wave of DRX, new grains form along the initial boundaries, necklace mechanism will be predominant recrystallization mechanism. In order to modeling the deformation behavior during hot rolling, one-hit compression tests were performed at temperatures of 950-1100 °C with strain rates of 0.01-1 s -1 . To study the dynamic recrystallization phenomena, the critical stress for initiation of dynamic recrystallization (? c ) should be determinded. Accordingly, it could be identified by the inflection point on the strain hardening rate (?=d?/d?) versus flow stress (s) curve. Several methods have been proposed to calculate this value on the basis of mathematical methods. One of them was proposed by Stewart, Jonas and Montheillet in which this critical point appears as a distinct minimum in the (-d?/d? versus ) through differentiating from ?versus ?. Another one was presented by Najafizadeh and Jonas which obtain by modifying the Poliak and Jonas method. According to this method, the strain hardening rate was plotted against flow stress, and the value of ? c was obtained numerically from the coefficients of the third-order equation that was the best fit from the experimental ?-? data. The result shows that the method presented by Najafizadeh and Jonas not only simpler than the previous one but also, it has a good agreement with microstructures. Furthermore, the normalized critical stress for this steel was obtained u c = ? c /? p = 0.92. The result shows that at the temperature of 1000 °C with the strain rate of 0.1 s -1 , DRX developed by necklace mechanism, it is far from completeness over the steady state stress. . .
