Observation of Inhomogeneous Deformation in a Cold-Rolled Ti-added Ultra-Low Carbon Steel using High-Precision Markers Drawn by Focused Ion Beam

Abstract

The development of deformation inhomogeneities in ultra-low carbon steel due to cold rolling has been investigated by observation of the longitudinal plane at chosen sites of a rolled sheet using SEM and SEM-EBSD techniques. Particular attention has been paid to the development of strain distribution in the crystals. The microstructures and the orientation distribution in the longitudinal plane of a sheet rolled to a 60% reduction in thickness were observed, and some grains with preferred orientation such as α-fiber and γ-fiber were selected. In order to examine the local strain distribution of these grains due to cold rolling, high-precision dot markers, 0.3μm in diameter, were drawn using a focused ion beam. Then, before being subjected to additional rolling, the sheet was fitted into a frame made of the same steel under a plane strain condition. Using the marker method, the local displacement of the grains due to cold rolling has been directly measured.