PSI - Issue 42

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V.K. Yadav et al., 2022/ Structural Integrity Procedia 00 (2019) 000 – 000

V.K. Yadav et al. / Procedia Structural Integrity 42 (2022) 594–601

597

Fig. 2. Engineering stress vs. strain for AA2024-T3 in various material conditions. The stress vs strain plot of the with and without corroded specimens, is shown in Fig. 2 and mechanical properties are listed in the Table 1. The average of three values for each material condition were considered, and are tabulated with their observed standard deviations. It revealed that plasticity of the material got reduced up to 85% after the welding process. This is probable due to the heterogeneous distribution of the grain structure across the weld cross section. As material’s strength depends on th e size of grains as suggested by Hall-Patch (Fratini et al. (2009)): σ ‰”ƒ‹ „‘—†ƒ”› α σ ƒ–”‹š Ϊ † ǦͳȀʹ ȋͳȌ where, k is constant, ’d’ is the grain size, and σ matrix is the strength of matrix material. Using this relation, it can be postulated that material having smaller grain size would have higher mechanical strength. Thus, weld nugget zone has better mechanical properties than the other region.

Table 1. Mechanical properties of the AA2024-T3 alloy.

Material condition

Yield strength (MPa)

Ultimate strength (MPa)

% Elongation

Fracture location

As-received

252 ± 4.51 233 ± 6.08 234 ± 5.20

408 ± 5.97 314 ± 7.30 304 ± 4.50

24.3 ± 0.72 4.07 ± 0.50 3.80 ± 0.15

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Weld (without corrosion) Weld (with corrosion)

Nugget/TMAZ TMAZ/HAZ

Tensile specimens often break in the region between weld nugget and thermo-mechanically affected zone. This transition region be the softened region of the welded joint as confirmed by the hardness-distribution across the weld

region (Yadav et al. (2020)). 3.2. Electrochemical Analysis

The open circuit potential (V ocp ) of the weld nugget zone was performed for 3600s, and compared with the as received material, as shown in Fig. 3. The potential-time behavior shows a negative value with small fluctuations. The open circuit potential value of the nugget zone is higher compared to as-received material. The initial open circuit