Measurements of lattice strain in cold-rolled CR4 steel sheets using X-ray diffraction

Abstract

In this study, the effect of orientation and bending has been investigated on CR4 steel for lattice constant, crystallite size and lattice strain. The one mm thick sheet of CR4 steel was bent through air-bending. The samples were prepared by using wire electric discharge machining (WEDM) followed by polishing for X-ray diffraction study. The peaks were analysed using QualX 2.1 software and lattice constant was analysed using Bragg’s law and lattice strain using Williamson-Hall’s method. Result shows, lattice constant is smallest on rolled face and after bending it increases along thickness. Whereas, the lattice strain is compressive in nature for all three orientations. However, for 0°orientation lattice strain (0.5%) is more across the thickness as compared to 90°orientation lattice strain (0.34%). Crystallite size was analysed by Scherrer’s method and Williamson-Hall’s method. Williamson-Hall’s crystallite size is observed to be smaller than Scherrer’s crystallite size. Further, crystallite size is observed to be the smallest on the rolled face. Moreover, after bending force application, enhancement in the lattice strain is observed while the size of the crystallite is reduced noticeably.