| dc.description.abstract | Today’s evolving technological landscape relies increasingly on small-scale components, which puts a premium on small-scale property data. The change in a material’s mechanical behavior as the working length scale is reduced is known as the size effect. In this paper, the effect of thickness on the mechanical properties of subscale tensile specimens is presented in two materials—Grade 2 and Grade 5 titanium. Thicknesses of 0.2 to 1 mm were tested, while the gauge width and length were held constant at 1 mm and 5 mm, respectively. Unpolished and polished specimens were both tested to understand the effect of surface finish on the properties, principally because Grade 5 titanium (Ti-6Al-4V) is widely known to be notch sensitive. The ultimate tensile strength (UTS) and yield stress (YS) for both materials were not shown to be thickness dependent. However, the total elongation and elongation at UTS showed a linear dependence with thickness according to the p-values of the Pearson’s correlation coefficients for the linear relationship, which were less than the chosen significance level of 0.05. The relationship between thickness and elongation is more significant in Grade 2, and this can possibly be explained by its greater necking propensity, which occurs more severely in thinner samples. That is, it necks through the entire thickness quicker in a thin sample than in a thick one. Grade 5 does neck, but it necks to a smaller degree than Grade 2. Therefore, the thickness effect is less pronounced. This investigation showed that thickness as well as the material’s inherent plastic response affects ductility. Additionally, two novel cross-sectional area measurement techniques were established to account for material loss due to polishing and to obtain a more accurate area, referred to as the optical method and the electrical resistance method. These methods are especially useful for instances where micrometers are known to result in significant error (e.g., situations where mass finishing or electro-polishing are used to improve the surface finish of samples). Accurate area measurement is a critical component of sub-scale testing, especially. | en |
