Research and development of laser additive manufacturing in Northwestern Polytechnical University

Research of Laser Additive Manufacturing (LAM) began at 1995 at the State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, China. The emphasis has been focused on obtaining excellent mechanical properties for LAMed metal parts through careful control of the material microstructures. The materials of LAMed parts include alloys of titanium, superalloys, and stainlessness steel. The mechanical properties of LAMed samples are usually in the classes of forging parts. A series of LAM equipments have been established with CO₂ and YAG lasers of several kilowatts of beam power as heat source respectively. The oxygen content of the argon filled chamber can be measured and controlled strictly. Full scale parts of titanium alloys, superalloys and compositional gradient material with complex structure have been LAMed. The maximum profile size of the LAMed parts is as large as 500mm. And LAMed parts are aimed at applications in aviation industries, optical mechanisms and medical fields. Furthermore, LAM is employed to repair mis-machined parts and to build up worn sections of metal components. A set of laser rapid repair equipment has been established with a robot as the movement mechanism.