Abstract
P91 steel weld joints made by multipass welding greatly alters the initial microstructure of the base metal and a thermally graded microstructure builds up across the weld joint due to its thermal sensitive nature. More so, when the weld joint is subjected to simultaneous cyclic loading and creep deformation, the initial microstructure of not only the base metal but also each constituting microstructural zone of the weld joint varies in a very complex manner depending upon the cyclic waveform employed. Four test conditions that represent four types of cyclic loading waveforms have been chosen for the present study. These are samples that were subjected to pure fatigue (without application of dwell), and samples that were exposed to an additional dwell period applied in each cycle at peak tension or peak compression or both peak tension and compression (represented as CC, 30 TH, 30 CH and 5 TCH respectively). All experiments were performed at 873 K and at 3 × 10−3 s−1 strain rate using total strain amplitude of ± 0.6%. Failure location shifted with the applied waveform. Microhardness line profiles on the longitudinal section of the fatigue failed samples were obtained at an inter-distance of 0.2 mm. The first-hand information obtained using this technique indicated that hardening/softening of the constituting regions of weld joint occurred to different extents and that was also waveform dependent. The microhardness correlated well with dislocation density obtained through EBSD.
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The authors are thankful to Indira Gandhi Centre for Atomic Research, Kalpakkam and Homi Bhabha National Institute, Mumbai for providing the opportunity to carry out this research.
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Vaishali, P., Shankar, V. Unraveling the Complexities of Deformation/Damage Incurred in P91 Steel Weld Joint During Creep–Fatigue Interaction Loading at 873 K. Trans Indian Natl. Acad. Eng. 7, 699–706 (2022). https://doi.org/10.1007/s41403-022-00319-1
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DOI: https://doi.org/10.1007/s41403-022-00319-1