PSI - Issue 28

Romanin Luca et al. / Procedia Structural Integrity 28 (2020) 162–170 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The choice of material hardening is often limited when using metallurgical couplings, such the case of Sysweld, to isotropic or kinematic hardening. An interesting alternative solution is the French open source code CodeASTER developed by EDF. Metallurgical capabilities are included with strong thermo-mechanical-metallurgical coupling and Chaboche material model for welding simulations. Krolo, Grandić, and Smolčić (2016) calibrated Chaboce parameters, with the scope of being used in seismic situations, from variable range tests. The noted that between the steel yielding and ultimate strength of cyclically loaded specimens, hysteresis stress-strain curves lie much higher than monotonic stress-strain curves. Temperature dependence of hardening parameters for the Lamaitre-Chaboche material model could be found in Bendeich et al. (2012) for typical pressure vessel steels utilized in the nuclear industry such as SA 508, AISI 316L and Inconel 182. Another problem is not just the availability of numerical models in widespread numerical codes but also the availability of material data at high temperature. A first step in this way is the calibration of the modified Chaboche unified viscoplasticity model on AISI 316 stainless steel has been performed by Gong et al. (2010). Tests up to 600°C have been performed. 3. Welding Phase In order to reduce welding deformation, welding is going to be performed from both sides simultaneously. A symmetrical residual deformed shape is expected and differences from nominal dimensions are going to be corrected introducing shims between the workpiece and the support, the bevel angle is of 50° to facilitate fusion at the root. The number of passes and the material deposited on each run is estimated from workshop experience. The weld passes sequence is reported in Fig. 2.

Fig. 2. Weld run sequence. The joint is welded symmetrically by the other side

The first pass has a depth of around 7.5 mm, the second and the third of about 5.5 mm and the last two capping passes reach nominal dimensions and have a width up to 9 mm. Welding parameters are taken from welding experience. Because it is a conceptual test, no welding macro is available to validate the thermal analysis. The welding parameters are reported in Table 1. It can be noted that the first run has a lower power because for the influence of the other torch of the symmetrical welding. The heat input has been applied utilizing the Goldak heat source (Fig. 3).