Experimental simulation of strip edge cracking in steel rolling sequences

摘要

The aim of this paper is to analyze the effect of cutting process on crack occurrence in metal forming, especially on strip edges. This study is performed within the field of cold rolling on an experimental testing stand by means of the Upsetting Rolling Test (URT). This test allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near industrial strip edges are deformed using the URT. A first set of specimens is submitted to two successive passes using extreme forward slips each. A second set of specimens is annealed to reduce edge strain hardening due to the cutting process. The same deformation configurations as for the first set of specimens are applied. SEM micrographs and optical surface profiler topographies of trimmed and deformed specimen edges show that forward slip has a major effect on opening of cracks. In the case of heat treated specimens hardness is decreased, characterizing a quasi homogenous material state. No cracks appeared after all reduction passes, which shows a large influence of the cutting process.