Direct laser deposition process fundamentals

The high manufacturing costs associated with aerospace alloys and components means that repair of the component is preferable to replacement. Performing a repair increases the in-service life of the component and removes the cost of manufacturing a new part. Blown powder Direct Laser Deposition (DLD) is an Additive Manufacturing technique capable of delivering high-integrity repairs on critical rotating aerospace components.

A key aspect of DLD is understanding how process inputs affect the final properties of the deposited material. The work presented here focuses on the DLD of Ti-6-2-4-6 as a repair method for compressor Blisks. The aim was to quantify the effects of process inputs on both the size of the α+β lamellar microstructure and the mechanical properties of the deposited material. This work was achieved through uniaxial tensile testing of specimens machined from as-deposited material, as well as microstructural analysis techniques. The experimental work was supported by a model, to aid the understanding of how different process inputs influence the laser deposition conditions. Initial results show a strong correlation between process inputs; powder feed rate and laser scan speed, and the ductility of the as-deposited material.

By quantifying this and other similar relationships, it will be possible to ensure a robust and repeatable repair technique for aerospace components, by identifying which process inputs will result in the required mechanical properties.