Tensile Testing  

Many times a casting is required to be under the force of a load. Therefore, it is important to know the capabilities of specific heat treated aluminum alloys in order to realize whether they will be successful for their intended purpose. Specific heat treatable alloys are chosen because of their capability to withstand large amounts of pressure being exerted upon them. One way of determining if a casting is capable of withstanding a large load is to perform a tensile test on the heat-treated material. By pulling the material apart, it can be determined how that specific material will react when a force is applied to it under tension. During a tensile test, a standard test piece of a desired alloy is gripped at both ends in a suitable machine. The test bars can be cast in an approved standardized mold as per ASTM B108 standards or can be directly cut out of a casting being manufactured. The machine slowly exerts a force along one of the test pieces axes and the metal is pulled so that it stretches until it breaks. During the pulling process several readings are taken and those reading are converted into three important measurements: Ultimate Strength, Yield Strength and % Elongation. The Ultimate Strength is the measure of the load at the point that the test piece fails and breaks. The Yield Strength is the point during the test where the load causes plastic deformation to take place. % Elongation is the measure of the percentage change in length before the material breaks. These three measurements are used in determining whether a material will be suitable for the intended purpose of the casting.

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