The ASTM E21 Elevated Temperature Tensile test method is used to determine the tensile strength, ductility, yield strength, elongation, and reduction of area of various metals under high temperature conditions. The results of tensile testing give an indication of a how a specimen will perform under various conditions such as during compression or shock. Testing for tensile properties at high temperatures is desirable because many components of machines must operate safely at elevated temperatures (eg. jet turbine blades). Specimens used for testing should be round, unless the material is in sheet or strip form.