Modeling of Bead-on-Plate Laser Beam Melting Using Innovative Laser with a Single-Mode Core Surrounded by a Multimode Ring

Laser beams are widely used in heat treatment and welding processes. Due to limitations of a single beam, hybrid solutions with dual beams have been developed. One of the newest approaches uses a single-mode laser as the core of the heat source combined with a surrounding multimode ring beam. The aim of this work is to develop a mathematical and numerical model of the power density distribution for such a combined laser source. The power distribution is described using a cylindrical-power-involution model. The model is applied to simulations of transient thermal phenomena during bead-on-plate laser melting of 4 mm thick S355 steel plates. The computational domain represents surface melting without a joint gap, and heat transfer occurs by conduction into a single plate. The predicted fusion zone and heat-affected zone are compared with macroscopic cross-sections of experimental bead-on-plate tracks. Good agreement confirms the suitability of the proposed dual-beam model for bead-on-plate laser processing of structural steel.