Browsing by Author "Rodrigues Pardal, Goncalo"
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Item Open Access Control of meltpool shape in laser welding(Springer, 2024-03-05) Suder, Wojciech; Chen, Xin; Rico Sierra, David; Chen, Guangyu; Wainwright, James; Rajamudili, Kuladeep; Rodrigues Pardal, Goncalo; Williams, StewartIn laser welding, the achievement of high productivity and precision is a relatively easy task; however, it is not always obvious how to achieve sound welds without defects. The localised laser energy promotes narrow meltpools with steep thermal gradients, additionally agitated by the vapour plume, which can potentially lead to many instabilities and defects. In the past years, there have been many techniques demonstrated on how to improve the quality and tolerance of laser welding, such as wobble welding or hybrid processes, but to utilise the full potential of lasers, we need to understand how to tailor the laser energy to meet the process and material requirements. Understanding and controlling the melt flow is one of the most important aspects in laser welding. In this work, the outcome of an extensive research programme focused on the understanding of meltpool dynamics and control of bead shape in laser welding is discussed. The results of instrumented experimentation, supported by computational fluid dynamic modelling, give insight into the fundamental aspects of meltpool formation, flow direction, feedstock melting and the likelihood of defect formation in the material upon laser interaction. The work contributes to a better understanding of the existing processes, as well as the development of a new range of process regimes with higher process stability, improved efficiency and higher productivity than standard laser welding. Several examples including ultra-stable keyhole welding and wobble welding and a highly efficient laser wire melting are demonstrated. In addition, the authors present a new welding process, derived from a new concept of the meltpool flow and shape control by dynamic beam shaping. The new process has proven to have many potential advantages in welding, cladding and repair applications.Item Open Access Data for paper entitled "Laser stabilization of GMAW additive manufacturing of Ti-6Al-4V components"(Cranfield University, 2019-05-09 12:07) Rodrigues Pardal, Goncalo; Martina, Filomeno; Williams, StewartData used in paper "Laser stabilization of GMAW additive manufacturing of Ti-6Al-4V components"Item Open Access Data supporting "A novel cold wire gas metal arc (CW-GMA) process for high productivity additive manufacturing"(Cranfield University, 2023-06-30 11:53) Wang, Chong; Wang, Jun; Bento, João; Ding, Jialuo; Rodrigues Pardal, Goncalo; Chen, Guangyu; Qin, Jian; Suder, Wojciech; Williams, StewartThis is a supplementary figure, showing the experimental setup for building the large-scale component with the CW-GMA process: (a) experiment setup, and (b) monitors for thermal camera and process camera.Item Open Access Efficient reduced-order thermal modelling of scanning laser melting for additive manufacturing(Elsevier, 2023-10-02) Chen, Guangyu; Ding, Jialuo; Sun, Yongle; Chen, Xin; Wang, Chong; Rodrigues Pardal, Goncalo; Williams, StewartAdditive manufacturing (AM) with a scanning laser (SL) to independently control melt pool shape has the potential to achieve part building with high geometric accuracy and complexity. An innovative dynamic convection boundary (DCB) method is proposed to develop a reduced-order finite element (FE) model to accelerate the thermal analysis of a SL process for AM. The DCB method approximates the thermal conduction of the adjacent material around the bead region by using a convection boundary condition that can be dynamically adjusted during the numerical solution. Thereby, a smaller problem domain and fewer elements are involved in the reduced-order FE modelling. A non-oscillating equivalent bar-shaped heat source was also introduced as a simplified substitution for a high oscillation frequency SL heat source. The DCB-based reduced-order thermal model achieved over 99% accuracy compared to the full-scale model but reduced the element amount by 73% and the computational time by 58%. The use of the bar-shaped equivalent heat source can further enhance computational efficiency without compromising the prediction accuracy of a high oscillation frequency SL process. The DCB-based reduced-order thermal modelling method and equivalent heat source could be adopted to boost extensive parametric analysis and optimisation for novel AM processes. Study on large structures AM could also be facilitated by simplifying the computation at critical regions. This study can also enable efficient thermal analyses of different manufacturing processes, such as welding, cladding, and marking.Item Open Access Efficient reduced-order thermal modelling of scanning laser melting for additive manufacturing.(Cranfield University, 2023-09-25 16:20) Chen, Guangyu; Ding, Jialuo; Sun, Yongle; Chen, Xin; Wang, Chong; Rodrigues Pardal, Goncalo; Williams, StewartThermal videos show the dynamic changing of the scanning laser melt pools with different oscillation frequenciesItem Open Access High temperature performance of wire-arc additive manufactured Inconel 718(Nature, 2023-03-20) James, William; Ganguly, Supriyo; Rodrigues Pardal, GoncaloIn developing a wire-arc directed energy deposition process for superalloys used in high-speed flight environments, Inconel 718 was deposited using a plasma arc process and tested for its high temperature performance. The deposited material was tested in both the as deposited condition and after an age-hardening industry standard heat-treatment for this alloy. Results showed a reduced performance in both deposited conditions, with heat-treated material significantly outperforming as deposited material up to 538 °C. The difference in performance was less significant from 760 to 1000 °C, owing to an in-test aging process which increased the performance of the as deposited material. The microstructure of deposited material showed significant cracking throughout the alloy and formation of secondary phases throughout the matrix, with significantly more precipitation after heat-treating.Item Open Access High‑temperature failure and microstructural investigation of wire‑arc additive manufactured Rene 41(Springer, 2023-01-11) James, William Sean; Ganguly, Supriyo; Rodrigues Pardal, GoncaloIn developing a wire-arc plasma direct energy deposition process for creep-resistant alloys used in high-speed flight applications, structures were built from nickel-based superalloy Rene 41. Samples of additive manufacturing (AM) material were analysed for their microstructural and mechanical properties, in both as-deposited (AD) and heat-treated (HT) conditions. Tensile specimens were tested at room temperature, 538, 760, and 1000 °C. Macroscopically, large columnar grains made up of a typical dendritic structure were observed. Microscopically, significant segregation of heavier elements, grain boundary precipitates, and secondary phases were observed, with key differences observed in HT material. There was a clear distinction between failure modes at different testing temperatures and between AD and HT variants. A fractographic investigation found a progressive move from brittle to ductile fracture with increasing testing temperature in both AD and HT conditions, as well as microstructural features which support this observation.Item Open Access A novel cold wire gas metal arc (CW-GMA) process for high productivity additive manufacturing(Elsevier, 2023-07-01) Wang, Chong; Wang, Jun; Bento, João; Ding, Jialuo; Rodrigues Pardal, Goncalo; Chen, Guangyu; Qin, Jian; Suder, Wojciech; Williams, StewartWire-arc directed energy deposition (DED) is suitable for depositing large-scale metallic components at high deposition rates. In order to further increase productivity and efficiency by reducing overall manufacturing time, higher deposition rates are desired. However, the conventional gas metal arc (GMA) based wire-arc DED, characterised by high energy input, normally results in high remelting and reheating at relatively high deposition rates, reducing the process efficiency and deteriorating the mechanical performance. In this study, a novel wire-arc DED process with the combination of a GMA and an external cold wire, namely cold wire-gas metal arc (CW-GMA), was proposed for achieving high deposition rate and low material remelting. The maximum deposition rates at different levels of energy input were investigated, with the highest deposition rate of 14 kg/h being achieved. An industrial-scale component weighing 280 kg was built with this process at a high deposition rate of around 10 kg/h, which demonstrated the capability of the process for high productivity application. It was also found that, due to the addition of the cold wire, the remelting was reduced significantly. The working envelope and geometric process model for the CW-GMA process was developed, which can be used to avoid defects in parameter selection and predict the geometry of single-pass wall structures. Moreover, the addition of the cold wire in the CW-GMA process reduced the specific energy density, leading to a reduction in both grain size and anisotropy, which improved the mechanical properties with increased strength and reduced anisotropy.Item Open Access Rene 41 Raw Tensile Data(Cranfield University, 2022-06-24 18:12) James, William; Ganguly, Supriyo; Rodrigues Pardal, GoncaloRaw tensile testing data of nickel superalloy Rene 41, manufactured using a plasma wire-arc directed energy deposition process.Item Open Access Rene 41 Tensile Data(Cranfield University, 2022-06-24 18:12) James, William; Ganguly, Supriyo; Rodrigues Pardal, GoncaloTensile testing data of nickel superalloy Rene 41, manufactured using a plasma wire-arc directed energy deposition process.Item Open Access A testbed for optimal coating selection for micromilling of biomedical grade TI-6AL-4V.(Cranfield University, 2019-07) Hawi, Sara; Goel, Saurav; Rodrigues Pardal, GoncaloOne of the biggest challenges in precision micro-machining of titanium alloys is the tool wear as titanium is characterised as a “difficult to cut” material. Tool coatings provide a promising solution for the problem of tool wear while offering a low cost high value machining route. This project aims to explore the design of engineering material systems along with machining parameters to guide the choice of tool coating while machining biomedical grade Ti-6Al-4V. The overarching aim is to identify a low cost tooling such as WC coated with the right coating composition together with the appropriate machining parameters. The research methodology applied to work towards this aim employs a design of experimental approach using the Taguchi method such that the spindle speed, feed rate and coating would be varied. Both qualitative and quantitative analysis of the machining process was carried out to qualify the machining performance. During the machining trials, data was gathered and analysed to study the effect of cutting parameters on the specific cutting energy, material removal rate and surface roughness.Item Open Access Thermal fluid dynamics of the effect of filler wire on deposition rate and bead formation intending plasma arc-based DED(Cranfield University, 2023-10-23 09:07) Chen, Xin; Wang, Chong; Ding, Jialuo; Qu, Rongdong; Wang, Yipeng; Rodrigues Pardal, Goncalo; Williams, StewartVideos of the simulations generated by this research.Item Open Access Welding and SEM - EDS data(Cranfield University, 2016-07-08 10:26) Rodrigues Pardal, Goncalo; Ganguly, Supriyo; Williams, Stewart; Vaja, JayWelding conditions reported on the paper.SEM-EDS data used in the paperItem Open Access Wire + arc additive manufacturing for high-speed flight.(2023-01) James, William Sean; Ganguly, Supriyo; Rodrigues Pardal, GoncaloThe use of Wire + Arc Additive Manufacturing (WAAM) to manufacture high- speed projectiles, such as missiles, is currently an industry challenge due to the nature of high-speed flight and the extreme environment that components are exposed to. Alloys that are suitable for high-speed flight are creep resistant superalloys, this is due to the aggressive heating environment experienced by objects in high-speed flight, and the need for performance at extremely high temperatures. These materials are currently expensive and difficult to manufacture, which is less than ideal for non-recoverable systems such as airborne weapons. The development of missile systems requires flight tests to be affordable and operate in quick succession, to which rapid prototyping offers a significant advantage. The use of traditional manufacturing methods and supply- chain for this purpose are logistically challenging and expensive, mainly due to loss of material though machining. The use of WAAM in a rapid prototyping capability is the driver for this research. To be able to use the process to manufacture and prototype components for high-speed applications, would, if possible, be an excellent solution to reducing the amount of time and money that it currently costs to flight-test and develop these systems. WAAM could also be used for final design production. The effect WAAM route has on the high temperature properties of superalloys is largely unknown. This research is therefore focused on the development of the WAAM process, and selection of alloys suitable for high-speed flight and for WAAM deposition. Four creep-resistant superalloys underwent deposition using a plasma WAAM process and the resulting material was characterised to understand how WAAM affects high temperature performance. The research also investigates post-deposition heat-treatment of these alloys and develops parameters for inter-pass machine hammer peening to improve material performance. The findings from this project increases the understanding between the WAAM process and superalloy strengthening mechanisms and develops a method to increase the performance of additive manufactured material. The most appropriate alloys for both WAAM and the high-speed flight application were ranked and down selected based on their anticipated performance and weldability. The selected alloys then underwent extensive testing from room temperature to 1000 °C, to understand the performance of WAAM built structures at high temperature. The microstructure is examined throughout and found key differences between solid-solution strengthened and age hardened alloys which effects performance. Finally, in-process machine hammer peening was investigated for age hardened Rene 41 and found to greatly increase the performance to match that of the wrought material.