Melting processes

Simulation of heat and fluid flow during laser-induced melting and re-melting

Computed melting trails in low-alloyed steel considering different levels of surface-active sulfur (low – medium - high)
© Fraunhofer IWS Dresden

Computed melting trails in low-alloyed steel considering different levels of surface-active sulfur (low – medium - high)

Laser-induced local melting of materials is important for a number of different kinds of laser-based manufacturing processes, such as surface modification (e.g. re-melting, alloying, coating) or heat-conduction mode laser beam welding of thin-section sheet metals. The melt pool’s shape and size in all these cases is considerably influenced by the melt flow caused by the typically high flow velocities as a result of the Marangoni effect. The Marangoni effect denotes the phenomenon of the acceleration of a fluid at a free surface due to the gradients of the surface tension that is in turn a strong function of temperature and activity of surface-active agents. Figure 1 shows simulated flow and temperature fields in corresponding melt trail cross-sections for different levels of surface-active sulfur (all other parameters were kept constant).

Laser-induced melting processes can be simulated at the IWS by use of the developed models. Parameter studies allow for an evaluation of strategies for the control of the penetration depth and the melt pool shape in corresponding applications.