Cold shaped changed different materials pressi̇ng investigation of material flow

Determination and evaluation of the friction coefficients is a very important issue due to its effect on the material flow pattern and deformation loads in deformation processes. Ring-compression test is a widely used experimental procedure for determination of the friction coefficients. Outer and inner diameters and the heights of the rings of material to be deformed are machined according to the 6:3:2 ratio and the change in inner diameter and height for various deformation ratios are recorded and compared with standard curves to determine the coefficients. Examination of the variation of the deformation on the rings' surfaces would help to better analyse the ring compression tests. In the presented study, an attempt is done to analyse the variation of the deformation on the ring specimen's surfaces. A grid pattern is drawn on the side and upper surfaces of the rings and photos of the final positions of the grids are taken for different upset ratios. Grid deformations and the standard friction coefficient determination procedure are used to analyse the ring-compression tests. Two different test materials are used in the tests and the friction coefficients for unlubricated conditions are harmonious with similar test results as expected. Variation in the grid dimensions with respect to deformation ratios and their positions on the specimen give a better analyse of the ring deformations.