Characterization of laser direct deposited metallic parts

Experimental Analysis of the Direct Laser Metal Deposition Process

“…However, the use of this equipment is justified and advantageous in mass and in large batches production. But when the part is unusual in form, has complex internal cavities or has to be made in small batches costs and time to prepare the production rapidly grow and, therefore, conventional technologies are practically unenforceables (Zhang et al, 2003).…”

“…(Lewis & Schlienger, 2000). Moreover, the high solidification rate, resulting from the narrow HAZ (Heat-Affected Zone), and the high temperature gradients, which are generated around the molten pool, allows a fine grain microstructure (Zhang et al, 2003). Another positive aspect of this process consists in the production speed increasing.…”

“…It is important to design an appropriate path, as it not only improves the quality of the final product, but also increases the efficiency of the manufacturing process. In the realization of the layers, DLMD technology incorporates laser cladding, a technique of metal surfaces coating performed by laser: so, someone calls it "three-dimensional laser cladding" (Zhang et al, 2003;Lu et al, 2001;Qian et al, 1997). The laser beam, through its heat energy, creates a molten pool with dimensions, on the XY plane, varying from half to five times the diameter of the focal spot, according to the adopted power and scanning speed.…”

Investigation into the effect of subsequent layer addition on the microstructure and properties of previous layers during direct laser deposition of 316L stainless steel

“…This is due to the unique and layer-wise approach to AM, which causes complex thermal gradients and reheating cycles that determine the resultant microstructure (Amine et al, 2014). Due to the rapid cooling experienced during AM processes, the parts tend to have fine microstructures, which have been shown to produce parts with mechanical properties better than wrought counterparts (Zhang et al, 2003) . The thermal gradients and directional cooling tend to lead to microstructures with a clear directional structure (Yu et al, 2012) (Zhang et al, 2014).…”

“…In this research a LENS 450 system is used to produce samples of 316L stainless steel and the effect of the subsequent layer addition on previous layers is investigated. 316L is an austenitic stainless steel that is commonly used for AM and is thus used in this research (Zhang et al, 2003) (Trelewicz et al, 2016) (Li et al, 2010). Austenitic stainless steels are of particular interest for direct laser deposition as they are relatively expensive to machine and have many potential uses (de Lima et al, 2014).…”