STP1480: Volumetric and Surface Positron Annihilation Studies of Fatigue Damage Accumulation in a Steel Alloy

    Glancey, Christopher D.
    Graduate Research Assistant and Professor, University of Idaho, Moscow, ID

    Stephens, Robert R.
    Graduate Research Assistant and Professor, University of Idaho, Moscow, ID

    Pages: 10    Published: Jan 2007


    Abstract

    Fatigue crack nucleation comprises a significant portion of the fatigue life for many structures. The ability to inspect and quantify damage before significant cracks appear could improve safety while allowing components to be retired only when they have reached the end of their useful life. Positron annihilation is one technique that allows for observation of damage accumulation on a much smaller scale than traditional nondestructive evaluation techniques. As-polished and shot-peened 300M steel specimens were fatigued under constant amplitude. Tests were interrupted at several fatigue life ratios between the as-received and failed conditions, and damage was measured with positron annihilation techniques. Positron annihilation was sensitive to both induced residual stresses and fatigue damage build up, but measurement uncertainty was high and sensitivity was low. Positron annihilation presents a potentially revolutionary nondestructive evaluation technique that could give a quantitative measure of early fatigue damage.

    Keywords:

    fatigue crack nucleation, nondestructive evaluation, positron annihilation, 300M steel


    Paper ID: STP45511S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP45511S


    CrossRef ASTM International is a member of CrossRef.