The art of coupon tests

Tensile coupon tests are commonly carried out to determine the material properties of metallic materials in research and industry. However, ambiguities are found in the current specifications in determining initial Young's modulus of material, which may lead to different test results. The material properties lay the crucial foundation in research and structural design. Different researchers may interpret coupon test results differently. Therefore, standard procedures of coupon test and the interpretation of test results are important and worth investigating. In this study, a series of tensile coupon tests on metallic materials, such as cold-formed carbon steel, cold-formed stainless steel and aluminum alloy, were carried out using different test and data analysis procedures. Two types of stainless steel materials, namely lean duplex and ferritic, were investigated. The test and data analysis procedures of loading rate on coupon specimens, determination of cross-sectional area of curved coupons and Young's modulus were carefully designed. In this study, tensile coupon test and data analysis procedures are proposed for both flat and curved coupons. The proposed procedures are able to eliminate possible errors and provide clear guidelines for tensile coupon tests.