Improved laser metal deposition (LMD) of nickel base superalloys by pyrometry process control

摘要

Laser metal deposition (LMD) with high power lasers consists of manufacturing precise layers of materials by fusing metal powder with a laser beam over a substrate. Typical dilution of 5% allows metallurgical adhesion of the coating. This technique provides a unique combination of high accuracy and low heat affecting zone which is attractive for processing high added value components such aeroengines. Nickel (Ni) base superalloys are widely used in aeroengines because of their high mechanical properties when working at high temperatures (creep). A repairing or manufacturing chain of these components by LMD requires a good understanding of many parameters; therefore process control plays an important role. This work is focused on the study of the LMD processing of a Ni base superalloy using two colour pyrometry for the process monitoring. Presented results show how temperature and cooling rates of the LMD tracks affect the shape, microstructure and corrosion of the LMD coatings.