(PS179)Nano-mechanical Analysis of SUS304L Stainless Steel with Bimodal Distribution in Grain Size

摘要

Previous works have clearly explained the co-relationship of matrix strength [1] and grain boundary effect [2] to the yield strength as described in Hall-Petch equation. Fine grained steels ensures higher strength but the grain refinement may lead to poor ductility in a trade-off relation. Zhang et al. [3] developed a material with good balance in strength and ductility by bimodal grain size distribution consisting of shell and core regions with fine and coarse grain sizes, respectively, named "harmonic structure". For further understanding the good mechanical performance in the material, local deformation behaviour and strengthening factors should be characterized for the individual regions. This paper is aiming at evaluating a local strength of grain interior of the fine (shell) and coarse (core) grains, which is associated with the first term in Hall-Petch equation, to separate strengthening factors of grain interior and grain boundary in the two regions for deeper interpretation of strengthening mechanisms.