In-situ monitoring and deformation characterization by optical techniques; part Ⅰ: Laser-aided direct metal deposition for additive manufacturing

摘要

Metal additive manufacturing (AM), being a transformational technology with unique capabilities, has received considerable attention from both industrial and academic sectors. To date, quality and repeatability are still regarded as the critical technological barrier that hinders their widespread applications, especially for high-value components with stringent requirements. One significant approach to overcome this formidable challenge is in-process monitoring combined with real-time closed-loop control, which has been explored by great research efforts. This paper describes ongoing work on the in-situ monitoring and characterization during processes of powder-fed laser-aided direct metal deposition (DMD), a form of metal AM. Much emphasis has been placed on the optical techniques, such as the temperature and morphology measurement of the melt pool by two-wavelengths pyrometers, and high-speed CMOS cameras, respectively. In particular, the state-of-the-art with respect to an emerging field-the full-field deformation monitoring of part and/or substrate by digital image correlation (DIC), is addressed.