Effects of Thickness Reduction on Tensile Behavior Using Proportional Specimens and Constant Aspect Ratio

The present paper focused on the analysis of thickness reduction effects on the tensile behavior. The low carbon ordinary steel with sheet thickness of 2.5 mm was initially considered. Face turning process was chosen to reduce thickness up to 0.4 mm. It was made at constant cutting speed on a 2-Axis CNC lathe machine. The geometry of the active part of a cutting tool, the cutting and feed speeds were chosen for minimizing the process effects in the sheet after thickness reduction. Proportional tensile specimens with constant aspect ratio were designed to have a fracture mode independent to the specimen size. Good repeatability of results proved the success of the experimental procedure. A ductile behavior with saturating strain-hardening was observed for different thicknesses. Stress-strain curves obtained at the three orientations showed a weak anisotropy effect. Quantitative analysis of the yield strength, the 0.2% offset yield strength and the ultimate tensile strength explored clearly a very limited effect of thickness reduction. The ductility characterized by the uniform and fracture elongations was more sensitive to thickness reduction than the material strength. The superimposition of the true stress-strain curves led to consider the curve of 2.5 mm thickness as reference for characterizing the post-necking strain-hardening behavior for all thicknesses.