Characterisation of quasi-stationary temperature fields in laser welding by infrared thermography: Charakterisierung von quasi-stationären Temperaturfeldern beim Laserstrahlschweißen durch Infrarotthermographie

J. A. Francis, S. Gach*, S. Olscho, U. Reisgen, A. Haeusler, A. Gillner, R. Poprawe

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

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    Abstract

    In this work, high-speed thermography is shown to effectively capture quasi-stationary temperature fields during the laser welding of steel plates. This capability is demonstrated for two cases, with one involving the addition of a ferritic-bainitic filler wire, and the other involving the addition of a low-transformation-temperature (LTT) filler wire. The same welding parameters are used in each case, but the temperature fields differ, with the spacing between isotherms being greater in the case where the low-transformation-temperature filler material is added. This observation is consistent with the differences in the extent of the heat-affected zone in each sample, and the shape of the weld pool ripples on the weld bead surfaces. The characterization of temperature fields in this way can greatly assist in the development of novel methods for reducing residual stresses, such as the application of low-transformation-temperature filler materials through partial-metallurgical injection (PMI). This technique reduces or eliminates tensile residual stresses by controlling the temperature fields so that phase transformations take place at the optimum times, and success can only be guaranteed through precise knowledge of the temperature fields in the vicinity of the welding heat source in real time.

    Original languageEnglish
    Pages (from-to)1283-1289
    Number of pages7
    JournalMaterialwissenschaft und Werkstofftechnik
    Volume48
    Issue number12
    Early online date10 Jan 2018
    DOIs
    Publication statusPublished - 10 Jan 2018

    Keywords

    • Cooling rate
    • heat-affected zone (HAZ)
    • phase transformation
    • residual stress
    • temperature measurement
    • welding thermal cycle

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