Browsing by Author "Eimer, Eloise"

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    Control of residual stress and distortion in aluminium wire + arc additive manufacture with rolling
    (Elsevier, 2018-06-25) Hönnige, Jan Roman; Colegrove, Paul A.; Ganguly, Supriyo; Eimer, Eloise; Kabra, S.; Williams, Stewart W.
    The aluminium alloy wire 2319 is commonly used for Wire + Arc Additive Manufacturing (WAAM). It is oversaturated with copper, like other alloys of the precipitation hardening 2### series, which are used for structural applications in aviation. Residual stress and distortion are one of the biggest challanges in metal additive manufacturing, however this topic is not widely investigated for aluminium alloys. Neutron diffraction measurements showed that the as-built component can contain constant tensile residual stresses along the height of the wall, which can reach the materials' yield strength. These stresses cause bending distortion after unclamping the part from the build platform. Two different rolling techniques were used to control residual stress and distortion. Vertical rolling was applied inter-pass on top of the wall to deform each layer after its deposition. This technique virtually elimiated the distortion, but produced a characteristic residual stress profile. Side rolling instead was applied on the side surface of the wall, after it has been completed. This technique was even more effective and even inverted the distortion. An interesting observation from the neutron diffraction measurements of the stress-free reference was the significantly larger FCC aluminium unit cell dimension in the inter-pass rolled walls as compared to the as-build condition. This is a result of less copper in solid solution with aluminium, indicating greater precipitation and thus, potentially contibuting to improve the strenght of the material.
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    Data: Effect of substrate alloy type on the hardness profile of the substrate and deposited material interface in Aluminium Wire + Arc Additive Manufacturing
    (Cranfield University, 2023-08-11 16:01) Eimer, Eloise
    This file provides the hardness measurements used in the paper to plot the different hardness profiles in figures 3 and 9 and the chemical composition measurement displayed in figure 10.
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    Data: Fatigue crack growth behavior in an aluminum alloy Al–Mg–0.3Sc produced by wire based directed energy deposition process
    (Cranfield University, 2023-08-04 15:41) Ye, Jin; Khadar Syed, Abdul; Zhang, Xiang; Eimer, Eloise; Williams, Stewart
    Additive manufacturing (AM) of Al-Mg-Sc alloys has received considerable interest from the aerospace industry owing to their high specific strength and suitability for AM. Since damage tolerance is a mandatory requirement for safety critical aerospace structures, this study has investigated the fatigue crack growth behaviour in an Al-Mg-0.3Sc alloy made by the wire and arc additive manufacturing. Tests were conducted with two different crack orientations at load ratios 0.1 and 0.5. At the lower load ratio and lower stress intensity factor range (10 MPa m1/2, isotropic crack growth rate property was measured; grain size effect was overcome by the mechanical factor (the stress intensity factor). At the higher load ratio 0.5, both the threshold and the critical values of the stress intensity factor range were reduced. Finally, the modified Hartman-Schijve equation was successfully employed to represent the crack growth rates including the threshold and the fast crack growth regions.
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    Effect of inter layer cold work on 2024 aluminium alloy produced by wire directed energy deposition
    (Elsevier, 2023-06-23) Eimer, Eloise; Ganguly, Supriyo; Czink, Steffen; Dietrich, Stefan; Chehab, Bechir; Ding, Jialuo; Williams, Stewart
    Aluminium copper magnesium alloys are widely used in the aerospace sector. Wire-based Directed Energy Deposition could replace conventional manufacturing routes to build large and semi-complex components for this industry if high mechanical performance can be achieved in the deposit. The scope of this study was to assess the effect of inter-pass rolling on a 2024 aluminium alloy wire-based DED built structure and to investigate the impact of cold work during the deposition process on the microstructure and mechanical performances. The 2024 aluminium alloy was deposited using two variants of gas metal arc process, and the effects of the deposition process, cold work and heat treatment were studied using macro and microstructural observations, hardness measurement and tensile tests. The material response to inter-pass rolling and the formation of rolling defects was found to depend on the deposition process variant and bead geometry. While a significant strengthening of the deposit was observed with one process, only a drastic reduction of defects was observed with the second. It was also found that the application of cold work and heat treatment led to lowering of anisotropy and higher ductility when compared with heat-treated deposit without any inter-pass rolling.
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    Effect of substrate alloy type on the microstructure of the substrate and deposited material interface in aluminium wire + arc additive manufacturing
    (MDPI, 2021-06-04) Eimer, Eloise; Williams, Stewart; Ding, Jialuo; Ganguly, Supriyo; Chehab, Bechir
    Wire + Arc Additive Manufacture is an Additive Manufacturing process that requires a substrate to initiate the deposition process. In order to reduce material waste, build and lead time, and improve process efficiency, it is desirable to include this substrate in the final part design. This approach is a valid option only if the interface between the substrate and the deposited metal properties conform to the design specifications. The effect of substrate type on the interface microstructure in an aluminium part was investigated. Microstructure and micro-hardness measurements show the effect of substrate alloy and temper on the interface between the substrate and deposited material. Microcracks in the as-deposited condition were only found in one substrate. The deposited material hardness is always lower than the substrate hardness. However, this difference can be minimised by heat treatment and even eliminated when the substrate and wire are made of the same alloy.
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    Effect of the deposition strategy on Al-Cu alloy wire+ arc additive manufacture
    (SVR Publishers, 2021-04-28) Ayarkwa, Kwasi Frimpong; Pinter, Zsolt; Eimer, Eloise; Williams, Stewart; Ding, Jialuo; Suder, Wojciech
    The effect of the deposition strategy on wire + arc additive manufacture (WAAM) has been conducted for aluminium alloys. In this study, oscillation and parallel deposition strategies were considered for thicker section linear wall building. The results indicate that the deposition strategy has a significant effect on mechanical properties and hardness of the WAAM structure. Optimum ultimate tensile and yield strength were identified after post-deposition heat treatment for both strategies. From microstructure analysis, it was observed that walls produced by oscillation deposition strategy were characterised by equiaxed grains whilst parallel deposited walls were characterised by a mixed grain structure consisting of columnar and equiaxed grains. It was also observed that parallel deposited walls showed an increased number of pores as compared to walls deposited using oscillation strategy. For the studies conducted on aluminium wire + arc additive manufacture, it has been found that the deposition strategy plays an important role in the quality of walls produced
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    Fatigue crack growth behavior in an aluminum alloy Al–Mg–0.3Sc produced by wire based directed energy deposition process
    (Wiley, 2023-07-29) Ye, Jin; Syed, Abdul Khadar; Zhang, Xiang; Eimer, Eloise; Williams, Stewart
    Additive manufacturing (AM) of Al–Mg–Sc alloys has received considerable interest from the aerospace industry owing to their high specific strength and suitability for AM processes. This study has investigated the fatigue crack growth behavior in an Al–Mg–0.3Sc alloy made by wire and arc additive manufacturing. Tests were conducted with two different crack orientations at cyclic load ratios of 0.1 and 0.5. At the lower load ratio, the horizontal crack showed a faster growth rate owing to the smaller grains and coarser second-phase particles that the crack tip had encountered when it propagated along the material build direction. The anisotropy in crack growth rate was mainly caused by the grain size effect. When the applied stress intensity factor range exceeded the value of 10 MPa m1/2, an isotropic crack growth rate between the two crack orientations was measured. This is due to the microstructural influence being overcome by the governing parameter of fracture mechanics. At the higher load ratio of 0.5, crack growth rate is isotropic, and the threshold stress intensity factor range was much lower than that tested under load ratio 0.1. Finally, the modified Hartman–Schijve equation has been successfully employed to represent the crack growth rates in all three regions.
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    From wire to component: aluminium lithium alloy development for wire and arc additive manufacturing
    (Springer, 2024-01-16) Eimer, Eloise; Ding, Jialuo; Williams, Stewart
    The Innovative Aluminium filler Wires for Aircraft Structures (IAWAS) project aimed to demonstrate the potential of Wire Arc Additive Manufacture (WAAM) for the production of aluminium lithium components. Preliminary testing demonstrated the possibility of depositing an 2395 aluminium lithium filler wire using a plasma arc heat source and a local shielding device. The deposit had a low porosity level but also low ductility caused by long, vertical, segregated grain boundaries. Both chemical composition and deposition conditions are known to impact the deposit microstructure. In-situ alloying, an efficient technique to develop new material, was implemented using plasma arc as a heat source on aluminium lithium alloys. The results aligned with the literature review on the impact of copper on crack sensitivity and led to the design of a new alloy. Unfortunately, the composition selected yielded challenges during the drawing process, and the filler material quality was poor, leading to a low WAAM deposit quality. Machine hammer peening was implemented on the AA2395 alloy, resulting in a drastic increase in ductility and yield strength of 480 MPa after solution treatment and ageing. This alloy was used to manufacture an aluminium lithium demonstrator to showcase the potential of WAAM to produce real-life components.
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    Hardness profile of the interface between the substrate and deposited material in Aluminium Wire + Arc Additive Manufacturing
    (Cranfield University, 2023-04-13 10:32) Eimer, Eloise
    This file provides the hardness measurement presented in the paper. The measurement are provided for all combination of alloy presented using the convention substrate alloy + WAAM alloy. The alloy combination are given in the sheet name.
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    Integration of substrate in aluminium wire and arc additive manufacturing
    (2019-04) Eimer, Eloise; Williams, Stewart W.; Ding, Jialuo
    Integrating wrought alloys into a wire and arc additively manufactured component is very beneficial in order to reduce the duration and cost of deposition. However the microstructure and therefore mechanical properties of the wrought and deposited materials will be different. This thesis reports on a study of the properties of integral parts made of a combination of wrought alloy and material deposited by Wire and Additive Manufacture. The study was divided into two parts. Firstly, high strength aluminium alloys were additively manufactured and studied. Secondly, the interface between additive manufactured material and wrought alloys was examined. Aluminium copper magnesium alloy was deposited by wire and arc, and its microstructure and mechanical properties were characterised using optical microscopy, scanning electron microscopy, and tensile tests in as-deposited, inter-pass rolled and heat treated conditions. In the as-deposited condition, the mechanical properties achieved were significantly lower than those of wrought material, with a yield strength up to 150 MPA lower than this achieved by heat treated wrought alloy. After heat treatment to the T6 temper, the inter-pass rolled WAAM material properties in the horizontal direction were similar to these of wrought products but with a high anisotropy. An investigation into depositing aluminium zinc alloys using the novel process of laser-assisted wire and arc. The process was studied using a video camera and a device measuring the electric arc characteristics. Optical and scanning electron microscopy were used to analyse the deposited material quality. The potential of the laser-assisted wire and arc process for deposition of zinc alloys was successfully demonstrated by depositing some three layer high structure in aluminium zinc with a very high zinc content. To examine the properties of the interface between deposited and wrought material, a large number of alloys from different aluminium alloy families, were used as substrates and wires. The microstructures of the interfaces were characterised using optical and scanning electron microscopy. The mechanical properties were evaluated using micro hardness, tensile test and digital image correlation. Combinations including aluminium lithium and aluminium zinc wrought alloys resulted in specific issues at the interface, such as porosity or hot cracking. However in general the interface did not have a detrimental effect on the interface yield strength which was the same as the yield of the deposited material. In the as-deposited condition, the maximum tensile properties were limited only by the deposited material or by the heat affected zone which depended on the substrate. Heat treatment made possible the partial or total recovery of the properties in the heat affected zone in the substrate. The mechanical properties of the deposited material were also drastically improved, resulting in a heat treated interface with higher mechanical properties than in the as-deposited condition. Inter-pass rolling reduced the level of porosity in the deposited material and could reduce the formation of cracks in between the first and second layer. However, the rolling of the first layer were an issue because of the proximity of the substrate and the resulting change in bead geometry. This can lead to lower mechanical properties in this area and could be detrimental to the properties of the interface. This project was funded by Constellium Technology Center.
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    Manufacture of large-scale space exploration components using wire + arc additive manufacturing
    (ICAS - International Council of the Aeronautics Sciences, 2022-11-28) Diao, Chenglei; Eimer, Eloise ; Mancini, Simone; Krishnaswamy, Surya; Schwarz, Florian; Pagone, Emanuele; Ding, Jialuo; Williams, Stewart; Pinter, Zsolt; Martina, Filomeno
    Cranfield University, Thales Alenia Space and WAAM3D together, combining their expertise knowledge and technologies on Wire + arc additive manufacture (WAAM), created a route for manufacturing large-scale space exploration Components using WAAM which could be used in future large scale-space exploration component manufacturing. In this project, several different sections of the development of WAAM technology are applied to manufacture a large-scale space exploration component including FEA simulation, inter-layer machining and cold work, intelligent toolpath planning and sustainability calculations. WAAM proved to be a very promising technique in future large-scale component manufacturing.
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    Mechanical performances of the interface between the substrate and deposited material in aluminium wire Direct Energy Deposition
    (Elsevier, 2023-01-06) Eimer, Eloise; Williams, Stewart; Ding, Jialuo; Ganguly, Supriyo; Chehab, Bechir
    Wire and Arc Additive manufacturing (WAAM) is a Direct Energy Deposition process suitable for the manufacture of large aluminium components. Additive Manufacturing can enable the production of functionally graded structure which could be done by integrating the substrate required to start the deposition into the final component. This paper aims to assess the possibility of including a substrate in a component by investigating the mechanical performances of the interface between a wrought plate and WAAM deposit. Four substrates alloys and 2319 WAAM alloy were investigated. Inter-layer rolling and heat treatment, process steps known for improving the properties of WAAM deposit, were implemented. Each interface was examined using microhardness profiles, tensile tests, post rupture fractography and microstructural analysis. The WAAM deposit hardness was lower than that of the substrate in the as-deposited condition. Although the interface had no impact when using the same alloy for both substrate and wire, the weakest point of the combination was at the interface in dissimilar alloy combination. Heat treatment reduced the properties difference between the substrate and WAAM deposit. Inter-pass rolling strengthen the WAAM deposit without impacting the substrate and eliminated the micro crack that occasionally formed in the fusion zone in the as-deposited condition.
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    Tensile properties, micro hardness and rupture surface images of aluminium 2024 wire Directed Energy Deposited material
    (Cranfield University, 2023-06-06) Eimer, Eloise
    This file provide the results of mechanical testing of the 2024 alloy deposited using the wire Directed Energy Deposition process.The scanning electron microscope images of representative rupture surface of each conditions tested are also provided.
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    Wire laser arc additive manufacture of aluminium zinc alloys
    (Springer, 2020-03-11) Eimer, Eloise; Suder, Wojciech; Williams, Stewart W.; Ding, Jialuo
    Aluminium zinc alloys are widely used in the aerospace industry due to their high strength. However, only a few studies have been reported on the additive manufacture of aluminium zinc alloys. This rarity is due to the difficulties occurring during the fusion processing of these alloys and to the lack of available raw material. This paper presents an alternative process used for the deposition of aluminium zinc alloys. In this study, a Wire Laser Arc Additive Manufacture (WLAAM) system was used. This consisted of a gas metal arc power source, used to generate the melt pool, and a laser beam applied to control the melt pool size. By using this approach, it was possible to produce an elongated melt pool and feed zinc into it with a cold wire without compromising the process stability. A welding camera along with a system measuring the arc voltage and current was used to monitor the process. Different process parameters and configurations were investigated along with their effect on process stability and deposited material microstructure. A very high zinc concentration was achieved in the deposited material without macro-segregation.