High-Temperature Tensile Testing of Micro-scaled Metal Foils Using Rectangular Samples by Resistance Heating-Assisted System Incorporating Digital Image Correlation with Laser Speckles

This study proposed to evaluate high-temperature tensile behavior of micro-scaled metal foils using rectangular samples by a resistance heating (RH)-assisted system incorporating digital image correlation (DIC) with laser speckles. High-temperature tensile tests were conducted for AZ31 magnesium alloys with a thickness of 0.05 and 2 mm in gauge width. To figure out the dominating factor that influences the temperature distribution of the foil with a micro-scale, the temperature of the samples for different materials with and without jig was simulated by finite element analysis and compared with the experimental results. As results, the heat conduction from the sample to the jig is the dominating factor that affects the temperature distribution of the micro-scaled foils rather than the thermal conductivity of the material. Furthermore, the measured temperature distribution and nominal stress–strain curves of rectangular samples show the same profiles with dog-bone samples. It turns out that the strain of micro-scaled metal foils can be measured accurately by the DIC system, in which the deviation of strains is less than 5% for the rectangular sample at the nominal strain larger than 0.05. In particular, the measurement of full strain field for the micro-scaled foils has been achieved. The anisotropy of the foils has been successfully evaluated. It is confirmed that rectangle is a suitable sample shape that can replace the conventional dog-bone shape in the tensile testing for micro-scaled foils by using RH method. The general applicability of the testing system has been proved.