Hall-Petch behaviour of 316L austenitic stainless steel at room temperature

The room temperature plastic deformation behaviour of two different batches (with differences in chemical composition) of 316L austenitic stainless steel has been studied. By thermomechanical treatments, a wide range of grain sizes varying from 2.7 to 64-0 mum was obtained in this study. The different microstructural parameters, such as grain size, distribution of grain size and shape, dihedral angle distribution, and grain aspect ratio were measured for annealed and deformed specimens of the two batches. The Hall -Petch behaviour of batch 1 showed two distinctly different linear regions, one in the fine grain size range (d less than or equal to 6 mum) and the other, in the coarse grain size range (d greater than or equal to 6 mum). The Hall-Petch parameter K-H (epsilon) was significantly higher in the fine grain regime than coarse grain regime at all strains. Hardness measurements were also performed across the grain at different strain levels. The applicability of the Hall-Petch relationship was assessed in batch 1 and batch 2. It was observed that the Hall-Petch relationship was applicable in the coarse grain regime and Kocks composite relationship in the fine grain regime of batch 1. In batch 2 of 316L austenitic stainless steel, a single linear Hall-Petch relationship could describe the deformation behaviour over the entire range of grain size (from 2.9 to 46 mum) studied. The variation of the Hall-Petch and Kocks composite parameters with strain was discussed in terms of changes in the microstructural parameters.