Thermal management during direct laser deposition (DLD) of Ti-6Al-4V components

McDonald, Katie (2015). Thermal management during direct laser deposition (DLD) of Ti-6Al-4V components. University of Birmingham. M.Res.

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Abstract

Direct Laser Deposition (DLD) introduces steep thermal gradients into components due to the localised, high temperature melt region created by the laser heat source. This causes local thermal expansion and plastic deformation during heating and leads to a permanent change in the geometry of the component. There is also an effect on the microstructure and therefore mechanical properties.
In this study, temperature measurements were taken across a substrate during DLD repair, under varying controlled thermal conditions This data was used to calculate the cooling rates at different locations, and these were correlated to the observed distortion of the substrate and changes in microstructure. It was found that cooling rate varied significantly at the outer edges of the substrate but hardly at all near the processing area, indicating that while the thermal gradient across the plate will affect distortion, it has little effect on microstructure.
The measured distortion was plotted against the cooling rate in the same location, showing evidence of an inverse binomial form relationship. Despite the relatively small size of the study this is an indicator of how the DLD process can be developed further.

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

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