Normal and abnormal grain growth in AISI304/304 Cu stainless steels

The grain growth kinetics in AISI 304/304 Cu grades have been studied after hot torsion tests and isothermal annealing at 1100 degrees C, 1150 degrees C and 1200 degrees C for times varying up to 400 seconds. Austenitic grain size is measured using an optical microscope coupled with an image analysis system by both circular intercept and boundary reconstruction methods. The mean grain size is shown to follow a D-n-D-0(n)=K.t law with n between 2.4 and 3.5. Authors propose to fit the measured grain size distribution using the Weibull density function. On the basis of the grain size distributions, an attempt is made to verify the Zener pinning theory modified by Gladman and to predict abnormal grain growth.