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Influence of weld-induced distortions on the stress magnification factor of a thin laser-hybrid welded ship deck panel
Published in J. Parunov, C. Guedes Soares, Trends in the Analysis and Design of Marine Structures, 2019
A. Niraula, M. Rautiainen, A. Niemelä, I. Lillemäe-Avi, H. Remes
Welded panels have local and global distortions formed during its production, for instance, during manufacturing of the plates, transportation, storing, and most significantly during welding. Thinner plates have lower bending stiffness than thicker ones, resulting in a higher susceptibility to weldinduced distortions and misalignments during the welding operation (Lillemäe et al. 2012, Eggert et al. 2012). Laser-hybrid welding has a lower heat input compared to the commonly used shielded metal arc welding (Fricke et al. 2015, Gupta 2017), which leads to smaller welding-induced distortions, better weld quality and consequently longer fatigue life (Remes et al. 2017). Still, with the thinner plates, welding induced distortions possess a significant impact on the fatigue life of deck panels as observed in previous research (Lillemäe et al. 2017, 2012, Remes & Fricke 2014, Lillemäe-Avi et al. 2017, Remes et al. 2017).
Beneficial Industrial Uses of Electricity: Materials Fabrication
Published in Clark W. Gellings, 2 Emissions with Electricity, 2020
A type of LBW, laser-hybrid welding, combines the laser of LBW with an arc welding method. This combination allows for greater positioning flexibility since the arc melting method supplies molten metal to fill the joint.
Influence of heat input on bead profile and microstructure characteristics in laser and laser-hybrid welding of Inconel 617 alloy
Published in Welding International, 2022
Mohd Aqeel, J. P. Gautam, S. M. Shariff
It is clear that the ROC increases with an increase in heat input in both ALW and LHW due to increase in the interaction time. It can also be seen that the ROC in wine-cup bead shape LHW is quite larger than that in Y-type bead shape of ALW and associated with prevailing heat inputs. The huge differences in depth and width of laser and arc penetration shape and separation of these two heat sources at neck zone in LHW leads to an increase in the ROC, whereas in ALW, the ROC obtained is due to the single concentrated CO2 laser beam heat source of diameter 180 µm with high energy density. In a similar study on laser and laser-hybrid welding performed by Gao et al. [27], reported strong detrimental effect of ROC on PMZ/HAZ liquation cracking susceptibility due to high heat accumulation and larger solidificaiton time occurring at neck zone of weld bead cross-section. They found that laser-hybrid welding process alters the temperature and strain distributions in the vicinity of fusion line which in turn ameliorates the cooling rates in the neck zone with magnitude of cooling rates being lower than that in laser alone welding. Thus, LHW due to the addition of two heat sources causing wider HAZ in neck zone and larger ROC that envisaged reduction of cooling rate in LHW than that of ALW and thereby resulting in less susceptibility to liquation cracking. As discussed in our previous research work [32], liquation cracks were formed along the GBs in PMZ propagated into the HAZ/FZ and were found predominantly at the neck zone in both LHW and ALW welds. Susceptibility to liquation cracking was found to be higher in case of ALW than in LHW plausibly due to high cooling rates associated in ALW. As shown in Figure 7(e), that the cooling rates at neck FZ in ALW are higher (1.65 × 105–1.91 × 105 K/s) than compared to LHW (0.52 × 105–0.69 × 105 K/s). On the whole, the influence of ALW and LHW processes on weld bead profile and microstructure analysis with critical assessment of ROC, a major factor for assessing liquation cracking susceptibility, addition of MIG to laser LHW played a deceive role in effectively altering weld microstructure and cooling rate at neck zones. Indeed wider MIG arc entails wider weld bead width and reduction in low cooling rate as compared to that of laser alone ALW process. As a result reduction in liquation cracking susceptibility in LHW as compared to that of laser alone ALW. Indeed stagnation of heat at the vicinity of ROC coupled with low cooling rate and temperature gradient in LHW weldments associated with MIG addition entailed relatively higher segregation with grain coarsening in PMZ and HAZ as compared to that of ALW counterparts. As a result ROC doubled in LHW with reduced cracking susceptibility as compared to that of ALW weldments. Therefore, the ongoing results suggested that the LHW process is beneficial over ALW process in terms of resistance to liquation cracking susceptibility and the ROC formation to primarily determine the occurrence of liquation cracking or weakening of strength at interface PMZ region.