PSI - Issue 66

7

Paolo Ferro et al. / Procedia Structural Integrity 66 (2024) 287–295 P. Ferro et al. / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 8 – Residual stress distribution along the paths shown in Fig. 3: a) transversal RS (  x ); b) longitudinal RS (  y )

RS results from a complex interaction between clamping conditions and thermal stress gradients, which can rationally explain different results obtained in the case of ‘zig-zag’ welding with respect to the linear counterpart. Indeed, due to the wider overall region undergoing welding for the zig-zag condition, the inner area of the welding undergoes a sort of ‘heat accumulation’ as compared to the external side where heat is dissipated more rapidly. For this reason, it is expected that the inner region of the welding experiences lower temperature gradients and therefore lower thermal stress. About the geometrical effect, it is reasonable to think that along the longitudinal direction, the restraint given by the parent material (PM) is lower than that induced by the PM in the standard welding. This results in an overall reduction of the longitudinal residual stress component in the ‘zig-zag’ welding compared to what occurs in the straight path welding. Figure 9 shows the distortion pattern induced by standard (Fig. 9a) and ‘zig-zag’ (Fig. 9b) welding pattern. The distortion of the cross-section 50 mm from the symmetry plane (coincident with the welding line in the standard welding) is shown, as well.

a

b

Fig. 9 – Distortion pattern [mm] induced by standard (a) and ‘zig-zag’ (b) welding path.

It is observed that the ‘zig-zag’ welding pattern slightly increases the plate distortion (  z) compared to the standard welding path. Finally, it is supposed that the differences in residual distortions and stress values between the two welding paths are strongly dependent on the ‘zig-zag’ parameters and future research should investigate such geometry effect.