Research on the metallurgical determinants of formability in electrogalvanized sheet

摘要

The effective coefficient of friction in draw-bead simulation tests of two-sided electrogalvanized steels (DBS-(mu)) varies significantly. Analysis of commercial samples suggests that the surface roughness and crystallographic texture of the coating are important variables. To isolate the effect of texture one-side galvanized samples of various textures were made in a laboratory simulator and tested in draw-bead simulation and strip-draw. The data show a consistent variation of DBS-(mu) with texture. Differences between the DBS and strip-draw tests apparently reflect differences in the degree of deformation on initial contact with the bead. The DBS-(mu) also increases when the surface is smooth on the microscale, probably because of interaction with the lubricant. However, the results do not seem to explain the quantitative differences between commercial specimens, which suggests that other metallurgical factors, such as surface roughness and the properties of the underlying steel, and often dominate.