Optimisation of the linear friction welding for Ti- 6Al-4V aero engine application

Wilson, Robin (2016). Optimisation of the linear friction welding for Ti- 6Al-4V aero engine application. University of Birmingham. Eng.D.

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Abstract

Linear friction welding (LFW) is a solid-state welding process (i.e. the melting temperature of the material is not reached) that is used for the fabrication of titanium alloy bladed discs (Blisks) in the fan and compressor stage of modern aero engines. Blisk technology enables a 20-30 % weight saving through removing the need for the dovetail attachment thus enabling slimmer, lighter and more streamlined disc architecture. This significant weight saving helps the aero engine meet environmental targets (ACARE, 2000) by reducing fuel burn, noise and emissions as well as eliminating fretting fatigue around the dovetail attachment and extending component life.
LFW is considered to be a self-cleaning process where contaminants trapped within the plasticised layer are expelled into the flash thus producing a high integrity weld that is stronger than the parent material. This high integrity is critical for Blisk application as contaminants in the final weld joint may result in reduced component life or sudden unexpected failure. Despite the importance of weld integrity for Blisk applications, little is known about the underlying process physics of the cleaning regime therefore the aim of this thesis is to provide a thorough mechanistic understanding of the weld evolution of Ti- 6Al-4V LFW by empirically evaluating weld efficiency, material flow behaviour and weld cleaning behaviour over a range of appropriate key process variables.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

Supervisor(s):