In-situ monitoring and defect detection for laser metal deposition by using infrared thermography

Aim of the presented approach is the early detection of defects (mainly material inhomogeneities like voids, delaminations, kissing bonds) occuring during the additive Laser Metal Deposition (LMD) process. Basis of the approach is the evaluation of the surface temperature gradient within the welding spot using a high speed thermographic sensor. Our contribution covers the following aspects:Estimation of the expected defect contrast by means of a simulation study Second pointExperimental setup and performed experimentsAchieved results on different welding parameters and mock-up defects together with the associated image processing chain First experiments showed that a set of process parameters can be monitored through the temperature signature of the welding spot. Also, the available defects have been detected down to a diameter of 0.5 mm. The presented work has been carried out within the research project 'ForNextGen' funded by the Bavarian Research Foundation and is pa rt of the work package 6 (Non destructive testing).