抄録
The caliber configuration design for creating ultrafine-grained steel bars through a groove rolling process was studied from the viewpoint of a large strain accumulation and cross-sectional shape variation in a bar. A three-dimensional finite element analysis was employed for this purpose. The square/foval (flat-like-oval)/square rolling was proposed as a method to introduce a large strain efficiently in material. The relation among the foval configuration, a strain and cross-sectional shape was examined in the groove rolling. The influence of the equivalent strain distribution by 1st pass (foval rolling) was considered to clarify the strain distribution and a cross-sectional shape by 2nd pass, and then the foval configuration to accumulate a large strain efficiently was shown. The optimum pass schedule to fabricate an ultrafine-grained steel of 13mm square bar from a 24mm square bar was proposed in warm groove rolling.
