Investigation on the direct laser metallic powder deposition process via temperature measurement

The direct laser metallic powder deposition process was investigated with the aid of a radiant thermometer by building thin walls. The measured infrared (IR) temperature signal showed good correlation with the deposition process and the quality of the deposited samples. The influence of the powder particle size and the z-increment on the quality of the deposited samples and the IR-temperature signal was examined. It was found that the particle size of the powders shows no significant influence on the measured IR-temperature signal and the deposition process. However, both the deposition process and the measured temperature signal depended strongly on the z-increment. The variation of the melt pool temperature and cooling rate resulted in an inhomogeneous dimension accuracy, microstructure and hardness of the deposited sample. An abnormal deposition process can be recognized by the IR-temperature signal.