Validation of a Theoretical Model for Laser Welding Thermal Field by Multi-Physics Numerical Simulation

Abstract

Theoretical models based on solutions of the conduction heat transfer equation have been widely proposed to calculate the thermal fields generated during laser welding, revealing simplification benefits and limitations in the accuracy of the results. In previous papers, the authors have introduced a parameterized analytical model based on the configuration of a virtual system of multiple mobile heat sources that simulates the effects of an actual keyhole welding mode by setting the system parameters so as to fit the calculated contours of the fusion zone in the weld cross-section of the experimental one. Even though a basic validation was already carried out by experimental detection, in order to further strengthen the model validity, this article deals with an extensive comparison between the results obtained by a multi-physics numerical simulation, performed by a commercial CFD software, and a theoretical one. The two different approaches were applied to the laser beam welding of butt-positioned AISI 304L steel plates. The investigation was focused on the effects of the keyhole on the main morphological features of the melt pool and fusion zone, and on the thermal fields obtained by the two models. The intrinsic differences between the two approaches, and how they are reflected in the corresponding results, were discussed. Satisfactory results were obtained by comparing the thermal fields, with a substantial convergence of the results, so as to validate the analytical model, assess the accuracy of its results, and define its application limits.

A Review on Fusion Welding of Dissimilar Ferritic / Austenitic Steels: Processing and Weld Metallurgy

“…In this regard, starting from the fusion line, Mas et al [28] documented the following sequence of solidification: cellular A mode (1), cellular AF mode (1, ), dendritic FA mode (1, 2, 2) with evidence of skeletal primary ferrite (Figure 11). In general, welding speed has important effects on cooling rates as investigated in literature by finite elements methods [76], using a commercial software [77], or by a new analytical model experimentally fitted on the weld cross-section contour, which was presented in [78] and validated in [79]. It would be appropriate to find articles that specifically deal with the effects of welding speed on cooling rates in welds between dissimilar steels.…”

A Review on Fusion Welding of Dissimilar Ferritic/Austenitic Steels: Processing and Weld Zone Metallurgy

“…In this regard, starting from the fusion line, Mas et al [28] documented the following sequence of solidification: cellular A mode (γ1), cellular AF mode (γ1, δ), and dendritic FA mode (δ1, γ2, γ2) with evidence of skeletal primary ferrite (Figure 13). In general, welding speed has an important effect on cooling rates as investigated in the literature by finite elements methods [80], using a commercial software [81], or by a new analytical model experimentally fitted on the weld cross-section contour, which was presented in [82] and validated in [83]. It would be appropriate to find articles that specifically deal with the effects of welding speed on cooling rates in welds between dissimilar steels.…”