The effect of thermomechanical welding on the microstructure and mechanical properties of S700MC steel welds.

Autor: Wang P; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria., Gomes FM; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria., Warchomicka FG; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria., Ernst W; Voestalpine Stahl GmbH, Voestalpine-Strasse 3, 4031 Linz, Austria., Vallant R; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria., Poletti MC; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria., Enzinger N; Institute of Materials Science, Joining and Forming at the Graz University of Technology, Kopernikusgasse 24/I, 8010 Graz, Austria.
Jazyk: angličtina
Zdroj: Welding in the world [Weld World] 2024; Vol. 68 (5), pp. 1053-1069. Date of Electronic Publication: 2024 Feb 15.
DOI: 10.1007/s40194-024-01711-x
Abstrakt: Grain refinement by plastic deformation during conventional TIG welding can help to compensate for the loss of mechanical properties of welded joints. The thermomechanical welding (TMW) tests were performed on S700MC steel with different combinations of TIG arc energy and high frequency hammering over three target cooling times (t 8/5  = 5s, 15s, and 25s). Additionally, the effect of initial microstructures on the weld joint quality was analysed by testing three materials conditions: hot-rolled (as-received) and cold-rolled with 10% and 30% thickness reductions, respectively. The effects of plastic deformation and the mechanical vibration on the grain refinement were studied separately. Optical microscopy, electron backscattered diffraction, and Vickers hardness were used to characterise the weld microstructure heterogeneity. The weld width and depth and the mean grain size were correlated as the function of cooling time t 8/5 . The results show that the weld dimensions increase with increasing the t 8/5 . The weld microstructures transformed from the mixed martensite and bainite into mixed ferrite and bainite with increasing the t 8/5 time, and the related mean grain size increased gradually. The TMW welds exhibit smaller grains compared to TIG welds due to the coupled effects of mechanical vibration and plastic deformation. The mechanical vibration contributes to weld metal homogenisation, accelerating TiN precipitation in the fusion zone. The proposed TMW process can refine the weld microstructure of S700MC steel, enhancing its mechanical properties.
Competing Interests: Competing interestsThe authors researched under the FWF project in Austria – Thermomechanical welding (No. 16732). The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article, and no potential competing interests.
(© The Author(s) 2024.)
Databáze: MEDLINE
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