STP626

    Effect of Specimen Taper and Machining Processes on Tension Test Results

    Published: Jan 1977


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    Abstract

    Tension tests on four steels showed that increasing the specimen taper resulted in increased strength values and decreased ductility values. The effect on most properties was small, but elongation was decreased substantially. Specimens were processed by grinding, turning, shot peening, and aging. Within the range used in normal specimen manufacture, few significant effects were observed. Tests were made using manually controlled, as well as computer-controlled, machines. Again, the differences were generally small, but the differences in tensile strength and elongation were statistically significant. These differences were attributed to twofold changes in strain rate and in the cross section area of the specimens. The strength properties from the computer-controlled machine were calculated manually and automatically. The values were not significantly different. Elongation appears to be the most sensitive and reproducible measure of procedural differences.

    Keywords:

    mechanical tests, tension, shape (taper), specimen, surface properties, finishes, machining, variability, grinding, turning, shot penning, aging, computation, computers, statistical analysis


    Author Information:

    Schmieder, AK
    Manager, Materials Testing Unit, General Electric Co., Schenectady, N. Y.


    Paper ID: STP27079S

    Committee/Subcommittee: E28.08

    DOI: 10.1520/STP27079S


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