STP1165: The Application of Transmission Electron Microscopy to the Study of a Low-Carbon Steel: HSLA-100

    Varughese, R
    Research associate and professor, The Pennsylvania State University, University Park, PA

    Howell, PR
    Research associate and professor, The Pennsylvania State University, University Park, PA

    Pages: 13    Published: Jan 1993


    Abstract

    Transmission electron microscopy (TEM) together with scanning electron microscopy (SEM) and optical microscopy have been employed to analyze the microstructures that develop in a copper-containing, low-carbon (0.04% by weight) HSLA-100 alloy. Specifically, the martensitic microstructures that develop in the simulated, coarse-grained heat-affected zones (HAZs) have been examined and compared with those that develop in the base plate during conventional quenching from the austenitic phase field. It has been shown that the lath martensitic packet size is increased dramatically in the HAZ as compared with the base plate. In addition, considerably more retained austenite is found in the HAZ. No evidence for the so-called granular bainite microconstituent has been found in either material. However, for cooling rates somewhat less than that experienced in the coarse-grained HAZ, a microconstituent that we term granular ferrite has been documented.

    Finally, the effect of tempering on the martensite in the base plate has been examined. As soon as they are observable, the copper (Cu) precipitates can be identified as face-centered cubic (fcc) ε-Cu.

    Keywords:

    steels, martensite, granular bainite, granular ferrite, copper precipitates, welding, heat-affected zones, transmission electron microscopy, scanning electron microscopy, light microscopy, metallography, metallurgical specimens, microstructure, metallographic techniques


    Paper ID: STP25102S

    Committee/Subcommittee: E04.03

    DOI: 10.1520/STP25102S


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