The effect of size on the mechanical properties of rolled specimen: predictions and experimental evaluation

Size effect is very important in microforming. Depending on the surface layer model, the effect of size on the mechanical properties is attributable to the difference between the mechanical properties of the surface and the interior of a specimen. The mechanical properties of the surface of rolled specimens are different from that of its interior due to the inhomogeneous strain distribution of the specimen during the rolling process. Therefore, the size effect on the mechanical properties of the specimen can be adjusted via the rolling process. The strain distribution of the specimen associated with rolling is affected by the material and process parameters. Therefore, the size effect on the mechanical properties of the rolled specimen is affected by these parameters. To investigate this idea, the effects of material and process parameters, such as the strain hardening exponent ( n ), tensile yield strength ( σ 0 ), strength coefficient ( K ), thickness of billet ( t ), and reduction ratio ( RR ), on strain distribution during rolling was examined using the finite element method. Moreover, the influence of the aforementioned parameters on the size effect characteristics of the mechanical properties of the rolled specimens was predicted according to the strain distribution. It was determined that the strain distribution of the specimens was more homogeneous with increasing n and t , or decreasing RR . The σ 0 and K had slight effects on the distribution. The size effect increased with increasing n and RR without surface cracks. Overall, there was good agreement between the experimental data and the predicted results.