Effect of Accumulative Bending Conditions on Grain Refinement on Hot-rolled Sheet (Development of Grain Refining Technology by Accumulative Bending Process)

As a technology to manufacture fine-grained steel, accumulative bending process after hot rolling was proposed, and multi-bending equipment of laboratory scale were established. The effects of accumulative bending on microstructure and ferrite grain size by changing the thermomechanical conditions were investigated. As the results, a microstructure with the grain size of 2.2μm was obtained at specimen surface by accumulative bending after hot rolling in the optimized thermal condition. By the results of FE analysis, it was cleared that equivalent strain was accumulated on not only surface but also center of thickness.