Effect of Processing Parameters on Thermal Phenomena in Direct Laser Metallic Powder Deposition

Direct laser metallic powder deposition technique is widely used in manufacturing, part repairing, and metallic rapid prototyping. The ability to predict geometrical accuracy and residual stress requires an understanding of temperature distribution during the deposition process. This study presents a numerical model of three-dimensional transient heat transfer in a finite model heated by a moving laser beam. Thermal phenomena in the process were investigated. The complex solid-liquid problem and latent heat of fusion were treated by means of equivalent thermal conductivity and modified specific heat, respectively. Using method of birth and death of elements, the growth of additive layers and the shape of melt pool were obtained. The effect of processing parameters such as absorbed power, travel speed, and preheated temperature on melt pool sizes and cross-section of deposited layer profile was studied. The results show that the melt pool sizes increase with absorbed power and decrease with travel velocity. In addition, the preheated temperature contributes less to the melt pool size. The results are generally in a good agreement with experiments in published literature.