STP520

    Fatigue Crack Propagation in Steel Alloys at Elevated Temperatures

    Published: Jan 1973


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    Abstract

    The fatigue crack propagation characteristics of three steel alloys were evaluated at room and elevated temperatures in an air environment. The alloys and temperature ranges were: A212-B (σYS = 40 ksi) 75 to 800 F, A517-F (σYS = 104 ksi) 75 to 950 F, and 9Ni-4Co-0.30C (σYS = 185 ksi) 75 to 650 F. The compact tension specimen was used for the 9Ni-4Co-0.30C and A517-F tests. A modified compact tension specimen having deep face notches in the crack plane was used for the A212-B tests. Fracture mechanics parameters were used to evaluate the crack propagation data. When plotted as a function of the stress intensity range, ΔK, the crack growth rates increased with temperature in A517-F and A212-B; temperature did not influence the 9Ni-4Co-0.30C data. Tests at reduced cyclic frequencies were conducted on A517-F and 9Ni-4Co-0.30C steel. The crack growth rates increased as the frequency was reduced in A517-F at 500 and 950 F. In 9Ni-4Co-0.30C the growth rates at 500 and 650 F were essentially the same for cyclic frequencies of 10 and 0.002 Hz over the range of growth rates investigated.

    Keywords:

    fatigue (materials), crack propagation, alloy steels, yield strength, creep properties, plastic deformation


    Author Information:

    McHenry, HI
    Project structures engineer, Convair Aerospace Division, General Dynamics, Fort Fort Worth, Tex.

    Pense, AW
    Professor of metallurgy and materials science, Lehigh University, Bethlehem, Pa.


    Paper ID: STP38852S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP38852S


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