Influence of specimen thickness with rectangular cross-section on the tensile properties of structural steels

Specimens with a rectangular cross-section are commonly used to measure the tensile properties of materials. However, the specimen size may influence the results. In this study, the tensile properties of FH550 and X80 steels were investigated using rectangular cross-section specimens with different thicknesses and the same width. Both an experimental study and a 3D finite element method (FEM) study have been conducted. The results show that the uniform elongation is independent of specimen size, but the post-necking elongation increases dramatically as specimen thickness increases, which was attributed to the stress distribution near neck region. Single factor analysis results show that both the yield and the ultimate tensile strength of the specimens are independent of the thickness when the specimen thickness is larger than 1 mm.