Titanium Alloy Repair with Wire-Feed Electron Beam Additive Manufacturing Technology

P Wanjara,M Brochu,C Bescond,J Gholipour,K Nezaki,P Patnaik,Q Yang,C De Formanoir,K Watanabe,S Godet

doi:10.1155/2019/3979471

Abstract

Wire feeding can be combined with different heat sources, for example, arc, laser, and electron beam, to enable additive manufacturing and repair of metallic materials. In the case of titanium alloys, the vacuum operational environment of electron beam systems prevents atmospheric contamination during high-temperature processing and ensures high performance and reliability of additively manufactured or repaired components. In the present work, the feasibility of developing a repair process that emulates refurbishing an “extensively eroded” fan blade leading edge using wire-feed electron beam additive manufacturing technology was examined. The integrity of the Ti6Al4V wall structure deposited on a 3 mm thick Ti6Al4V substrate was verified using X-ray microcomputed tomography with a three-dimensional reconstruction. To understand the geometrical distortion in the substrate, three-dimensional displacement mapping with digital image correlation was undertaken after refurbishment and postdeposition stress relief heat treatment. Other characteristics of the repair were examined by assessing the macro- and microstructure, residual stresses, microhardness, tensile and fatigue properties, and static and dynamic failure mechanisms.

Highlights

Fleet managers and operators in the aerospace sector, faced with ever-increasing demands to lower operational costs, have sought repair and rejuvenation solutions to maximize the utilization, availability, and lifespan of their assets
During electron beam additive manufacturing (EBAM), the temperatures measured by means of the two thermocouples attached to the surface of the Ti6Al4V substrate (as indicated in Figure 1(a)) permitted examination of the thermal evolution at the midthickness and midwidth regions close to (∼2 mm from) the deposition interface
At the start of the deposition process, the substrate was at room temperature. en, the process was started with the EB positioned next to thermocouple 1, and during the deposition of the first layer, the EB passed over thermocouple 2. e thermal history arising from the cyclic heating cycles during the EBAM, as shown in Figure 5, indicates that the midwidth region of the substrate experienced higher temperatures relative to the edge

Summary

Introduction

Fleet managers and operators in the aerospace sector, faced with ever-increasing demands to lower operational costs, have sought repair and rejuvenation solutions to maximize the utilization, availability, and lifespan of their assets. In commercial and military gas turbine aeroengines, the commonly applied repair scheme for refurbishing extensively eroded first stage titanium alloy fan blades involves sequential operations of (1) inspecting and removing the foreign object debris and damage, (2) preparation of the repair patch by stamping, rolling, or forging, (3) prerepair coating removal and cleaning, (4) fan blade and patch positioning, alignment, and fixturing, (5) fusion welding of the repair patch using tungsten inert gas, hot wire metal inert gas, laser, and/or EB welding, (6) postweld heat treatment, (7) final machining, and (8) nondestructive inspection [1, 2] This repair procedure can involve long turnaround times and high costs due to material preparation of the repair patch, prerepair setup, and postrepair machining. DED technologies have evolved from welding based platforms, traditionally designed for joining, cladding, coating, and repair [8,9,10,11], that have been integrated with computer-aided design software and, increasingly, with

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Conclusion