Segregation of Mn, Si, Al, and Oxygen During the Friction Stir Welding of DH36 Steel

M. Almoussawi, Alan Smith, Masoumeh Faraji, S. Cater

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    4 Citations (Scopus)
    8 Downloads (Pure)

    Abstract

    This work investigates the role of welding speed
    in elemental segregation of Mn, Si, Al, and oxygen during
    friction stir welding (FSW) in DH36 steel. The experimental
    work undertaken showed that when the speed of the
    FSW process exceeds 500 RPM with a traverse speed of
    400 mm/min, then elemental segregation of Mn, Si, Al,
    and O occurred. The mechanism of this segregation is not
    fully understood; additionally, the presence of oxygen
    within these segregated elements needs investigation. This
    work examines the elemental segregation within DH36
    steel by conducting heat treatment experiments on unwelded
    samples incrementally in the range of 1200–1500 C
    and at cooling rates similar to that in FSW process. The results of heat treatments were compared with samples
    welded under two extremes of weld tool speeds, namely
    W1 low tool speeds (200 RPM with traverse speed of
    100 mm/min) and W2 high tool speeds (550 RPM with
    traverse speed of 400 mm/min). The results from the heat
    treatment trials showed that segregation commences when
    the temperature exceeds 1400 C and Mn, Si, Al, and
    oxygen segregation progress occurs at 1450 C and at a
    cooling rate associated with acicular ferrite formation. It
    was also found that high rotational speeds exceeding
    500 RPM caused localized melting at the advancing-trailing
    side of the friction stir-welded samples. The study aims to estimate peak temperature limits at which elemental
    segregation does not occur and hence prevent their occurrence
    in practice by applying the findings to the tool’s
    rotational and traverse speed that correspond to the defined
    temperature.
    Original languageEnglish
    Pages (from-to)569-576
    JournalMetallography, Microstructure, and Analysis
    Volume6
    Issue number6
    Early online date13 Nov 2017
    Publication statusPublished - Dec 2017

    Keywords

    • Friction stir welding
    • DH36 steel
    • Elemental segregation

    ASJC Scopus subject areas

    • Materials Science(all)
    • Engineering(all)

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