Hall-Petch behaviour of 316L austenitic stainless steel at elevated temperatures

Abstract

The plastic deformation behaviour of two different batches (having differences in chemical composition) of 316L austenitic stainless steel has been explored in the 200-800°C temperature range as a function of grain size. The plastic behaviour is correlated with microstructural observations of annealed and deformed samples. The microstructural parameters measured in this study are grain size, grain size and shape distribution, grain aspect ratio, and the distribution of dihedral angles. Hardness measurements were also performed to assess the hardness profile across the grains. The applicability of Hall-Petch relationship was tested in the 200-800°C temperature range. It is observed that the Hall-Petch relationship is applicable in the coarse grain regime (d≥6 μm) and Kocks composite relationship (σ versus d-1) in the fine grain regime (d≤6 μm) of batch 1 samples in the 200-600°C temperature range. At 800°C, the Hall-Petch data is widely scattered and the scatter increases with increasing strain. The variation of Hall-Petch parameters and Kocks parameters with strain and temperature are analysed on the basis of changes in the microstructural parameters. The operating deformation mechanisms in different temperature and strain ranges are discussed on the basis of variation of microstructural parameters with strain and temperature.