Welding thermal stress diagrams as a means of assessing material proneness to residual stresses
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Welding thermal stress diagrams as a means of assessing material proneness to residual stresses Andrii Mishchenko1 and Ame´rico Scotti1,2,3,* 1
Laprosolda-Center for Research and Development of Welding Processes, Federal University of Uberlandia (UFU), Uberlândia, MG, Brazil 2 Division of Welding Technology, Department of Engineering Science, Production Technology West, University West, Trollhättan, Sweden 3 Graduate Program in Materials Science and Engineering, Federal University of Parana (UFPR), Curitiba, PR, Brazil
Received: 19 May 2020
ABSTRACT
Accepted: 22 August 2020
In this work, the proposal and appraisal of a method to describe in a quantitative manner the phenomenon of thermal stresses formation in welding at different heat-affected zone (HAZ) regions and under different cooling rates, by means of physical simulation, are explained. Under the denomination of welding thermal stress diagrams (WTSD), initially the concept and experimental arrangements needed to use the idea, based on a Gleeble simulator, are revealed. An approach to determine more realistic thermal cycles (peak temperature and heating/cooling rates) is introduced and applied. The method assessment was carried out by using specimens of a HSLA quenchable steel subjected to different cooling rates (covering a wide range of typical welding heat inputs) and peak temperatures (representing regions progressively farther away from the fusion line). The different thermal stress (TS) curves proved the concept based on the justification of the results. In addition, it was physically demonstrated that TS curves are governed mainly by two complex concurrent phenomena, namely contraction under restriction of heated areas and the expansibility of phase transformation. It was concluded that due to this balance, the highest residual stress (RS) does not occur either at slowest cooling rate or at fastest cooling rate. Nevertheless, the highest RS may not occur at the coarse grain zone either. TS progressively drops along the HAZ regions away from critical regions, and even at sub-critical regions there is tensile RS. Complementarily, it was also concluded that WTSD by physical simulation allows one to determine the deformation behaviour of a material as a function of temperature. This information can be used as input or calibration in modelling for thermal stress generation in steels.
Published online: 21 September 2020
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The Author(s) 2020
Handling Editor: Nathan Mara.
Address correspondence to E-mail: [email protected]; [email protected]
https://doi.org/10.1007/s10853-020-05294-y
J Mater Sci (2021) 56:1694–1712
1695
Introduction Heat input physical simulation in welding is achievable by submitting a material to typical welding thermal cycles. Thereafter, the metallurgical response of this material under these thermal cycles is reached without doing actual welding. Traditionally, physical simulations of welding focus on studying the influence of thermal cycle operational parameters (heating and cooling rates and peak temperature) on the microst
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