Strain distribution and microstructural evolution in multi-pass warm caliber rolling

The three-dimensional finite element-analysis and electron backscattered diffraction analysis are used to study quantitative correlation between effective strain and deformed microstructure in low carbon steel bars fabricated through multi-pass warm caliber rolling. The strain imposed in the rolled bars has a distribution with maximum at around corners, and large strain of over 5.7 is introduced into corners when nominal reduction in area is 89%. The area of around corners introduced strain over 5.7 is filled with the ultrafine ferrite grains of below 680 nm. It is shown that microstructural parameters, the fraction of high angle grain boundaries (HAGBs) and the average misorientation, not only depend on strain imposed but also local reduction in area.