PSI - Issue 68

T.N. Examilioti et al. / Procedia Structural Integrity 68 (2025) 756–761 T.N. Examilioti et al./ Structural Integrity Procedia 00 (2025) 000–000

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Standard tensile specimens were machined from the welded sheets, according to ASTM E8 specification, in transverse (T) direction with the weld being in the middle of the gauge length. The dimensions of the specimens were 200 mm in length and 25 mm in width. Tensile mechanical tests were carried out on a Zwick Roell RM 100 machine equipped with a 100 kN load cell. The deformation of the marked gauge length was determined by using a Fiedler Opto-Electronic (FOE) laser extensometer with an accuracy of 0.01 mm. 3. Analysis of the tensile mechanical performance The mechanical test results were derived from previous publications of the authors, e.g., Examilioti et al. (2024) and Examilioti et al. (2021). Conventional yield stress R p0.2% results, presented with average values and standard deviations for various PWHT conditions using different filler material and nominal thicknesses, can be seen in Fig. 1a and 1b , respectively. For the case of AA4047 filler material, yield stress presents a continuously increase from the as-welded (AW) condition to 48 h at 170 o C, followed by a slightly decrease up to 98 h and over-ageing condition, ( Fig. 1a ). In contrast, the AA2319 filler material present lower conventional yield stress for all ageing times. More specifically, exhibits higher lower yield stress in comparison to AA4047 filler material by approximately 72 % in the case of under ageing condition. Lower decrease can be noticed in peak-ageing condition about 5 %, for the case of AA2319 when compared to AA4047 filler material. This enhancement in mechanical strength is attributed to the continued growth of T 1 and θ’ phases with increasing ageing times, (Tao et al., 2018). According to Examilioti et al. (2021), the higher Cu content in the filler materials increases the volume fraction of Cu-containing precipitates in the fusion zone, thereby enhancing their strengthening effectiveness and resulting un a significant rise in yield stress. Yield stress results for PWHT specimens with the use of AA4047 filler material and under different nominal thickness are presented in Fig. 1b . It can by noticed that the 5.0 mm thickness present higher results in comparison to the 3.2 mm for all ageing times. Higher yield stress can be noticed in PA condition by approximately 38 %. a b - !

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Fig. 1. Yield stress values of LBWed AA2198 specimens under different ageing conditions for (a) different filler materials; (b) different thicknesses.

The elongation at fracture results for specimens with different filler material and under different artificial ageing times are shown in Fig. 2a . For both AA4047 and AA2319 filler materials, elongation at fracture decreases with increasing ageing times post to the weld, reaching reductions of approximately 90 % and 80 %, respectively, and after 98 h at 170 o C. Similar results have also been reported by Examilioti et al. (2021) and Ning et al. (2017) for the AA4047 and AA2319 filler materials, respectively.