o ) are measured to enable calculations of strain and % reduction in area to be made. In a typical tensile testing machine the specimen is held in place by special grips,. One end of the specimen is held firm, whilst a hydraulic piston forces the other grip away from it. Thus producing the tensile load within the specimen. The specimen and grips can be seen on the machine below. Note that an electronic device for measuring the specimen extension, an extensometer, is mounted on the specimen. This has to be removed once the specimen approaches its proportional limit or it will be damaged when the specimen breaks. Following the failure of the material, the specimen is re-assembled.  It has the appearance as shown below when compared to the original pre-test specimen.  The gauge length at failure (L f ), and the final cross sectional area (A f ) are measured.  The original gauge length and the final gauge length are used to calculate the percentage elongation of the specimen at failure.  The original cross sectional area and the final cross sectional area are used to calculate % reduction in area. Information that can be obtained from a tensile test: As well as calculating % elongation at failure and % reduction in area at failure, the load-extension graph is converted to an engineering stress/strain curve by converting the graph axes from load to stress (load divided by cross sectional area), and by converting extension to strain (% elongation). Stress-strain graphs