Investigations of Process Optimization, Microstructure Modification and Material Performance Improvement in High Deposition-rate Laser Metal Deposition of Inconel 718

• Antragsteller: Dr.-Ing. Andres Gasser
• Fachliche Zuordnung: Produktionsautomatisierung und Montagetechnik
• Förderung: Förderung von 2016 bis 2020
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 317809677

It is one of the most important developing trends of the modern manufacturing industry to realize the integrated designand fabrication of large-scale metal components with short delivery time, which is exactly one of the key developmentdirections of Laser Metal Deposition (LMD). This project focuses on the High Deposition-Rate LMD (HDR-LMD) ofInconel 718 (IN718) which is a typical precipitation strengthened nickel based super-alloy and widely used in the inaircraft engine industries. Compared with conventional LMD (deposition rate ~0.5kg/h), the aim in HDR-LMD is thedeposition of several kilograms per hour. On one hand, material defects, such as porosity and cracking which aredetrimental for material performance, occur more often. The laser intensity distribution and the powder streamdistribution as well as the powder characteristics and gas environment have strong effects on material defects. On theother hand, the as-deposited material has a lower strength and a higher ductility, which is believed to be a result of thelower scale and degree of Nb segregation. Thus, it should be possible to achieve superior material performance bytaking advantage of the microstructure characteristics. Therefore, we propose the following work. Initially, in order touse the laser energy efficiently and suitably, the matching between laser intensity distribution and powder stream willbe established, based on which a HDR-LMD nozzle will be developed/adapted. Afterwards, the effects of powdercharacteristics on material defects will be investigated, and furthermore the quality specifications for powder used forHDR-LMD will be proposed. Then, based on process monitoring (high speed camera & thermal camera) andmetallographic analysis the process will be modeled, and the material microstructures will be correlated with processparameters. Finally, the microstructure will be modified by adjusting process parameters, and moreover the adaptedheat treatment process will be developed to treat the as-deposited material to improve material performance, whichkeeps partially the high temperature Laves phases with granular morphology as a second strengthening phase. Thismay be a remarkable innovation to improve the service temperature for IN718.

• DFG-Verfahren: Sachbeihilfen