STP97

    Stress Determination in Cast Irons for Railroad Service

    Published: Jan 1950


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    Abstract

    The determination of stresses in cast iron parts for railroad service has promoted both safety and performance. Serious errors may be encountered, however, if the stress-strain relationships of the particular cast iron structure being studied are not known, since strain measurement is the usual experimental method of finding the stress pattern. The first portion of the paper indicates that shape and amount of graphite may normally change the modulus of elasticity from 26 × 106 psi. to 10 × 106 psi. Total elongation varies from 5.5 to 0.18 per cent and tensile strength from 78,000 to 25,000 psi. Type of matrix may also affect the stress-strain curve since in some soft irons the shape of the graphite may cause permanent set at very low stresses. The second portion of the paper is devoted to measurement of strains during press fitting and to determination of residual stresses after different types of heat treatment. The apparent anomaly of tensile cracks in a quenched bore surface under residual compressive stress is explored. Finally, different cases of slow cooling, resulting in opposite residual stresses, are analyzed.


    Author Information:

    Flinn, R. A.
    American Brake Shoe Co., Mahwah, N. J.

    Ely, R. J.
    American Brake Shoe Co., Mahwah, N. J.


    Paper ID: STP48075S

    Committee/Subcommittee: A04.21

    DOI: 10.1520/STP48075S


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