The orbital friction welding process for engines components in aeronautic

Jérémy Escaffre,Yann Lefaux,A Lenain

doi:10.1051/matecconf/202032104024

Abstract

Titanium alloys are key materials in engines due to their low density, their high mechanical properties and their good resistance to corrosion and oxidation. Titanium engine parts are manufactured most of the time by forging, giving good mechanical properties associated with the possibility to optimize final microstructures of the parts. Due to design challenges consisting of making parts more robust and lighter, new processes are emerging. For some parts, friction welding can give opportunities to achieve those objectives because these assemblies are characterised by very good mechanical properties, generally higher than the raw unwelded materials [1]. As a consequence, the friction welding process is finding increasing applications as a manufacturing technology for the production of titanium alloy Ti-6Al-4V aerospace components [2]. Among those processes, the Orbital Friction Welding (OFW) technology is under study for low pressure compressors manufacturing. The BLuM® (Bladed drum, Figure 1), is constituted of a drum comprising several stages of friction-welded blades. Such architecture allows an important weight saving and performances improvement compared to current design. The objective of the article consists of addressing the orbital friction welding process, through the description of its characteristics, the key process parameters, the microstructures and the way of ensuring good integrity of the interface. The objective of the article consists of addressing the orbital friction welding process, through the description of its characteristics, the key process parameters, the microstructures and the way of ensuring good integrity of the interface.

Highlights

Considering the environment of engines and the aeronautic challenges, titanium alloys are key material for this type of application
Safran Aero Boosters invests heavily in research and development in order to rise up the main challenges facing the aerospace industry and to provide more added values to customers
The use of friction welding was identified as a way to take fully advantage of this new architecture

Summary

Introduction

Considering the environment of engines and the aeronautic challenges (mass saving, sustainability and performances), titanium alloys are key material for this type of application. Welding by friction the blades on the drum is a sustainable process, improving considerably the “buy to fly ratio” compared to forging and machining a hog-out part of this size Such way of manufacturing allows to avoid the use of a large size forged shape (with larger grain size) which considerably decreases the high cycle fatigue properties of the parts. For those reasons, Safran Aero Boosters developed and validated the BLuM® (Bladed drum, Figure 1). If the microstructure of the raw material is a classical α-β forged TA6V, the orbital friction welding allows to obtain a very fine b forged microstructure with excellent mechanical properties in the welded joint (cf Figure 5). The welded joint have stronger fatigue resistance than the raw material, the number of cycles to failure of welded specimens are included in the deviation of the unwelded specimens

Validation methodology

Findings

Conclusions