Volume 11, Issue 3 (May 1983)
Fractographic Examination in the Scanning Electron Microscope as a Tool in Evaluating Through-Thickness Tension Test Results
The through-thickness tension test is used to assess resistance to lamellar tearing. Observed through-thickness reduction-of-area (TTRA) values are usually well above the 20% minimum specification level in steels produced for lamellar-tearing-resistant applications. Low TTRA values, when encountered, indicate susceptibility to lamellar tearing but provide little indication of the source of premature fracture. Fractographic examination, especially with the scanning electron microscope, provides information about the origins of low ductility. Sources of premature fracture discussed herein are indigenous inclusions, exogenous inclusions, occluded hydrogen, undissolved alloy additions, and solidification microvoids.