Comparing the properties of solid-state welds produced with emerging nickel superalloys

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Franklin, Katherine (2020). Comparing the properties of solid-state welds produced with emerging nickel superalloys. University of Birmingham. Ph.D.

Franklin2020PhD.pdf
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Abstract

Nickel-based superalloys are the material of choice for use in high temperature applications within the jet engine. Rolls-Royce Plc is developing the next generation of nickel-based superalloys for a gas turbine jet engine, to allow the increase of engine temperatures, and improve efficiency.

This project aims to assess the microstructural and mechanical properties of development nickel superalloys following solid-state welding.

Inertia welds were undertaken on development alloys (V207s135H, V202-2 and Alloy 12-1) and compared to the current alloy of choice, RR1000. Assessment of the welding process found a linear relationship between increasing the secondary ’ volume fraction and a decreasing amount of upset produced during inertia welding. Following solid-state welding, development alloys display closely similar microstructural and micro-hardness profiles to RR1000. Sustained load testing revealed: 1) Weld line residual stresses were found to be present following moderate PWHT; influencing the threshold stress intensity factor (k). 2) High PWHT was successful in removing residual stresses in RR1000 and V207s135H, but not in V202-2 and Alloy 12-1. 3) Crack-growth rates are an order of magnitude higher in V207s135H compared to RR1000 at high k values.

Research results were used by Rolls-Royce Plc to down-select next generation superalloys for gas turbine jet engines.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):