Uniform formation of fine grained ferrite structure through multi-directional deformation

:A multi-directional deformation thermo-mechanical treatment simulator was designed and developed to verify the prediction by the FE-analysis on the e ffect of bi-directional deformation which can introduce a large plastic str ain widely in a specimen. Using this simulator, both uni-directional and hi -directional deformations were performed for a 0.16%C-0.4%Si-1.4%Mn steel w ith a prior austenite grain sire of 300 mum at 1073K at a strain rate of 1/ s. The microstructure was composed of polygonal ferrite and intragranular W idmanstatten ferrite in the uni-directional deformation specimen. On the ot her hand the half thickness of the specimen was composed of fine polygonal ferrite in the bidirectional deformation specimen. This region corresponds well to the region having a plastic strain of more than 2. The uniform form ation of the fine polygonal ferrite due to the wide introduction of the lar ge plastic strain was verified for the hi-directional deformation.