The ASTM E8 standard describes tensile testing methods to determine yield strength, yield point elongation, tensile strength, elongation, and reduction of area for metals. It applies to metallic materials in any form: sheet, plate, wire, rod, bar, pipe, and tube.
When performing strain measurements, such as the strain corresponding to the yield strength, we typically recommend an automatic extensometer. Using an automatic extensometer, such as the AutoX750, helps reduce operator influence on the test while also ensuring accurate data. You can see this more clearly in the above video.