The effect of printing parameters on the deformation and microstructure of Inconel 718 : A study in pulsed laser and powder based directed energy deposition additive manufacturing

Sammanfattning: Additive manufacturing has the power to redefine how we create components. In order to minimize removal of printed material, deformation must be kept a minimum. When deposition rate is increased during directed energy deposition so is the power requirement for melting the feedstock. This increases the residual stresses in the material and leads to more deformation. The deposition rate must be increased without introducing large deformation, if additive manufacturing is ever to be economical in many engineering fields. This study aims to explore if pulsing the laser can decrease deformation using a design of experiments approach. Other types of defects and microstructural changes are also evaluated. A total of 17 sets of parameters were used varying laser power, pulse frequency and the time fraction when the laser was powered on. The amount of powder added to a substrate was constant and the build geometry as similar as possible for all tests. Ultimately no conclusion could be drawn regarding pulsing parameters effect on deformation. It was found pulsing the laser lowered the powder efficiency drastically, which may have had a bigger effect on the experimental set up than anticipated. In a similar manner, no relation between pulsing parameters, defects and microstructure could be observed.