PSI - Issue 13

Yoshiki Mikami et al. / Procedia Structural Integrity 13 (2018) 1804–1810 Author name / Structural Integrity Procedia 00 (2018) 000–000

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Fig. 1. (a) geometry and dimensions of the groove; (b) cross section of the fabricated multipass welded joint.

Fig. 2. (a) Location of strain gauges in multipass welds; (b) location of strain gauges on the cut surface; (c) measured residual stress distribution.

3. Through process modeling of multipass welding and fracture toughness test In this study, the entire process starting with multipass welding, specimen machining, residual stress modification, and three-point bend test was modeled. The weld residual stress distribution is an important initial input; therefore, the numerical simulation of multipass welding and its validation were performed first. Then, the results were incorporated into the subsequent simulation steps. 3.1. Residual stress simulation of multipass welded joint The finite element model for the multipass welded joint is shown in Fig. 3. The weld metal is divided into 61 passes, as shown in Fig. 3(b), based on the cross-sectional observation of the welded joint. Material properties used for the simulation are the same as those reported by Mikami et al. (2017). Phase transformation, temperature dependency, and isotropic strain hardening were taken into consideration. The welding heat input was determined based on the experiment and was introduced pass-by-pass. The deposition of weld passes and gouging were modeled using an element activation/deactivation technique. The contour figure of the residual stress distribution obtained by the simulation is shown in Figs. 4(a) and (b). Figure 4(c) presents the comparison of through-thickness distribution with the experimental result at the center of the weld length (along line B). The simulation result was in good agreement with the measurement; therefore, the simulation result was used in the following simulations.

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55917 nodes 52182 elements

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Fig. 3 Finite element model for the multipass welded joint; (a) overall view; (b) cross-section of welds and weld pass deposition sequence.