Laser Consolidation - A Novel One-Step Manufacturing Process for Making Net-Shape Functional Components

Abstract : Free-form laser consolidation is a novel manufacturing process that produces a functional complex part layer by layer directly from a CAD model without any moulds or dies. This process uses a laser beam to melt a controlled amount of injected powder on a base plate to deposit the first layer and on previous passes for the subsequent layers. As opposed to conventional machining processes, this computer-aided manufacturing (CAM) technology builds complete functional net-shape parts or features on an existing component by adding instead of removing material. Laser consolidation of Ni-base IN-625 and IN-738 superalloys, Ti-base Ti-6Al-4V alloy, Co-base Stellite 6 alloy and Fe-base CPM-9V tool steel has been investigated. The laser consolidated (LC) materials are metallurgically sound, free of cracks or porosity. Due to the rapid solidification inherent to the process, excellent material properties are obtained. The as-consolidated Ti-6Al-4V material shows tensile and yield strengths comparable to the heat-treated wrought Ti-6Al-4V. The LC Stellite 6 is harder, stronger and even more ductile than the respective material produced by conventional casting or powder metallurgy method. The average stress rupture life of LC IN-738 specimens at given test condition is substantially longer than that of cast IN-738 baseline samples. Pin-on-disk wear tests demonstrate that the wear loss of the LC CPM-9V material is only about 1/3 compared to that of the heat treated D2 tool steel currently being used for many tool and die applications. The LC samples also show very good surface finish and dimensional accuracy. Surface finish of the order of 1~2 microns (Ra) is obtained on as-consolidated IN-625 samples. In this paper, laser consolidation process will be introduced, the functional properties of the laser-consolidated materials will be described, and the potential applications of the process will be discussed.