Browsing by Author "Ding, Jialuo"
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Item Open Access Achieving a columnar-to-equiaxed transition through dendrite twinning in high deposition rate additively manufactured titanium alloys(Springer, 2024-04-09) Davis, A. E.; Wainwright, J.; Sahu, V. K.; Dreelan, D.; Chen, Xin; Ding, Jialuo; Flint, T.; Williams, Stewart; Prangnell, P. B.The coarse β-grain structures typically found in titanium alloys like Ti–6Al–4V (wt pct, Ti64) and Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242), produced by high deposition rate additive manufacturing (AM) processes, are detrimental to mechanical performance. Certain modified processing conditions have been shown to lead to a more refined grain structure, which has generally been attributed to a change in the solidification conditions with respect to the experimental Hunt diagram proposed by Semiatin and Kobryn. It is shown that with Wire Arc AM (WAAM) increasing the wire feed speed (WFS) is effective in promoting a columnar-equiaxed transition (CET). Conversely, estimates of the dendrite-tip undercooling using the KGT model suggest that this will be too small for free nucleation without the addition of artificial nucleants, due to the very low solute partitioning in Ti alloys. It is also shown that it is difficult to promote a CET with plasma transferred arc WAAM as computational fluid dynamics (CFD) melt-pool simulations indicate that the solidification parameters remain within the columnar region on the Semiatin-Kobryn Hunt map, within the constraints of a stable process. However, a high fraction of twin boundaries was observed in the refined β-grain structures seen at high WFS. This has been attributed to departure of {001}β alignment from the direction of maximum thermal gradient, caused by the curvature of the fusion boundary, stimulating dendrite twinning during solidification. In addition, it is shown that increasing the WFS leads to a change in melt-pool geometry and a reduction of remelt depth, which promoted dendrite twinning and grain refinement.Item Open Access Additive manufacturing of a functionally graded high entropy alloy using a hybrid powder-bed wire-based direct energy deposition approach(Elsevier, 2023-01-23) Lu, Yao; Wang, Jun; Williams, Stewart; Zhu, Lisong; Ding, Jialuo; Diao, Chenglei; Jiang, ZhengyiA functionally graded AlxCoCrFeNi high entropy alloy with a variation in Al concentration along the building direction was in-situ produced using a hybrid powder-bed wire-based direct energy deposition process. A continuous transition from a single FCC structure to a major BCC+minor FCC dual-phase structure was achieved, benefiting from the remelting and reheating process during the deposition. In the FCC→BCC transition zone, the dendritic core region is identified as an FCC matrix decorated by AlNi-rich ordered B2 precipitates. The interdendritic area shows B2 precipitating in the FeCr-rich disordered A2 matrix. Additionally, the interface between the two regions shows that the A2 phase and ordered Cr3Fe intermetallic phase precipitate at the B2 phase. The mechanical properties show a tendency for higher strength and hardening rate but lower plasticity corresponding to the areas with higher Al content. Through quantitative estimation of different strengthening mechanisms, the contribution from precipitation strengthening became increasingly apparent as Al content increased. Other strengthening modes, including solid solution and dislocations, also contribute to the total strength. This investigation realises a novel additive manufacturing method combining powder bed and wire feeding, which can produce a more convenient and cost-effective gradient material with a complex composition.Item Open Access Assessing the effect of TIG alternating current time cycle on aluminium wire + arc additive manufacture(Elsevier, 2017-10-09) Ayarkwa, Kwasi; Williams, Stewart W.; Ding, JialuoThe effect of electrode positive time cycle (% EP) of the alternating current TIG process has been investigated for aluminium wire + arc additive manufacture of linear walls. The study considered the effect on oxide removal, linear wall dimensions, microstructure, mechanical properties as well as the effect on electrode wear. The results showed that the effective wall width was minimum at 20%EP with a corresponding maximum in layer height. It was also observed that increasing the% EP increased the electrode wear rate, which in turn affected the arc stability. Microstructure analysis showed a noticeable increase in the grain size for higher% EP. The study also showed that% EP had no significant effect on mechanical properties. From a heat input analysis, a direct correlation was observed between the arc voltage and the% EP. The study also indicated that there could be other contributing factors to wall dimensions. For aluminium wire + arc additive manufacture of linear walls, minimum cleaning ranged between 10%EP and 20%EP.Item Open Access Automated interlayer wall height compensation for wire based directed energy deposition additive manufacturing(MDPI, 2023-10-16) Qin, Jian; Vives, Javier; Raja, Parthiban; Lasisi, Shakirudeen; Wang, Chong; Charrett, Thomas O. H.; Ding, Jialuo; Williams, Stewart; Hallam, Jonathan Mark; Tatam, Ralph P.Part quality monitoring and control in wire-based directed energy deposition additive manufacturing (w-DEDAM) processes has been garnering continuous interest from both the academic and industrial sectors. However, maintaining a consistent layer height and ensuring that the wall height aligns closely with the design, as depicted in computer-aided design (CAD) models, pose significant challenges. These challenges arise due to the uncertainties associated with the manufacturing process and the working environment, particularly with extended processing times. To achieve these goals in an industrial scenario, the deposition geometry must be measured with precision and efficiency throughout the part-building process. Moreover, it is essential to comprehend the changes in the interlayer deposition height based on various process parameters. This paper first examines the behaviour of interlayer deposition height when process parameters change within different wall regions, with a particular focus on the transition areas. In addition, this paper explores the potential of geometry monitoring information in implementing interlayer wall height compensation during w-DEDAM part-building. The in-process layer height was monitored using a coherent range-resolved interferometry (RRI) sensor, and the accuracy and efficiency of this measurement were carefully studied. Leveraging this information and understanding of deposition geometry, the control points of the process parameters were identified. Subsequently, appropriate and varied process parameters were applied to each wall region to gradually compensate for wall height. The wall height discrepancies were generally compensated for in two to three layers.Item Open Access Bead shape control in wire based plasma arc and laser hybrid additive manufacture of Ti-6Al-4V(Elsevier, 2021-07-16) Wang, Chong; Suder, Wojciech; Ding, Jialuo; Williams, Stewart W.Wire based plasma transferred arc (PTA)-laser hybrid additive manufacture has the potential to build large-scale metal components with high deposition rate and near-net shape. In this process, a single bead is the fundamental building block of each deposited component, and thus the bead shape control is essential for the deposition of different geometries. However, how to control the bead shape by manipulating various process parameters is still not understood. In this study, the effect of different process parameters, including laser power, energy distribution between the PTA and laser, wire feed speed, travel speed, and laser beam size on the deposition process and bead shape was investigated systematically. The results show that the optimum operating regime for the hybrid process is with the wire being fully melted by the PTA and the melt pool being controlled by the laser, which gives a good bead shape as well as a stable deposition process. The bead shape is significantly affected by the laser power and travel speed due to the large variation in energy input. The effect of wire feed speed is more complex with the bead width initially increasing to a maximum and then decreasing as the wire feed speed increases. The laser beam size has a minor effect on the bead shape, but a small beam size will result in an irregular bead appearance due to the unstable process caused by the high power density. In addition, a procedure for controlling the bead shape in the hybrid process was proposed, which provided a reference for selection of different process parameters to achieve required bead shapes. The feasibility of this proposed procedure was demonstrated by the two deposited multi-layer single-pass walls.Item Open Access Bead shape control using multi-energy source (mes) for wire-based directed energy deposition (ded) process.(Cranfield University, 2021-11) Chen, Guangyu; Ding, Jialuo; Williams, Stewart W.Independent control of layer width and height is essential to achieve a simultaneous high build rate with precision net shape and thermal control independent from deposition shape in the wire-based directed energy deposition (w-DED) process. Bead shape control using a multi-energy source (MES) method was studied to achieve independent control of layer width height of a bead for the w-DED process. This study was carried out in three stages: First, a plasma transfer arc (PTA) energy density measurement was conducted. A split anode calorimeter (SAC) was applied for the measurement of PTA energy density. A laser beam with a well-defined energy profile was used to calibrate the calorimeter without the complications of arc instability. An optimised centred grounded SAC device was introduced to reduce arc distortion. More symmetric arc profiles were obtained. The dynamic thermal characterisation of a scanning laser (SL) was then studied using both experimental and numerical approaches. SL experiments were conducted with different oscillation frequencies and laser beam sizes. An innovative solution dependent convection boundary (SDCB) method was introduced to reduce the element amount of the finite element (FE) model. Results show that the quasi-steady state SL can be applied as an equivalent stationary energy source. Finally, an SL-PTA MES system was introduced to study the MES bead shape control, a PTA was employed in the front to create an initial melt pool and melt the feedstock wire, and an SL was used behind the PTA to reshape the melt pool and precisely control the bead width. A bead shape control strategy was proposed by using the wire feeding rate to control the layer height and the scanning width to control the layer width. The experiment results verified that the SL-PTA MES has independent control of layer width and height.Item Open Access A comparative study of additively manufactured thin wall and block structure with Al-6.3% Cu alloy using cold metal transfer process(MDPI, 2017-03-10) Cong, Baoqiang; Qi, Zewu; Qi, Bojin; Sun, Hongye; Zhao, Gang; Ding, JialuoIn order to build a better understanding of the relationship between depositing mode and porosity, microstructure, and properties in wire + arc additive manufacturing (WAAM) 2319-Al components, several Al-6.3%Cu deposits were produced by WAAM technique with cold metal transfer (CMT) variants, pulsed CMT (CMT-P) and advanced CMT (CMT-ADV). Thin walls and blocks were selected as the depositing paths to make WAAM samples. Porosity, microstructure and micro hardness of these WAAM samples were investigated. Compared with CMT-P and thin wall mode, CMT-ADV and block process can effectively reduce the pores in WAAM aluminum alloy. The microstructure varied with different depositing paths and CMT variants. The micro hardness value of thin wall samples was around 75 HV from the bottom to the middle, and gradually decreased toward the top. Meanwhile, the micro hardness value ranged around 72–77 HV, and varied periodically in block samples. The variation in micro hardness is consistent with standard microstructure characteristics.Item Open Access Compensation strategies for robotic motion errors for additive manufacturing (AM)(University of Texas, 2016-08-10) Bandari, Yashwanth K.; Charrett, Thomas O. H.; Michel, Florent; Ding, Jialuo; Williams, Stewart W.; Tatum, Ralph P.It is desirable to utilise a robotic approach in additive manufacturing as Computer Numerical Control (CNC) is expensive and it has high maintenance costs. A robotic approach is relatively inexpensive compared to CNC and can provide much more flexibility, enabling a variety of configurations and easier parallel processing. However, robots struggle to achieve high positioning accuracy and are more prone to disturbances from the process forces. This paper attempts to characterise the robot position and velocity errors, which depend on the build strategy deployed, using a laser speckle correlation sensor to measure the robotic motion. An assessment has been done as to whether these errors would cause any problem in additive manufacturing techniques, where the test parts were built using the Wire+Arc Additive Manufacture (WAAM) technique. Finally, different compensation strategies are discussed to counter the robotic errors and a reduction of 3 mm in top surface profile irregularity by varying the wire feed speed (WFS) during the path has been demonstrated.Item Open Access Computationally efficient models of high pressure rolling for wire arc additively manufactured components(MDPI, 2021-01-04) Gornyakov, Valeriy; Sun, Yongle; Ding, Jialuo; Williams, StewartHigh pressure multi-layer rolling is an effective method to reduce residual stress and distortion in metallic components built by wire arc additive manufacturing (WAAM). However, the mechanisms of the reduction in residual stress and distortion during multi-layer rolling are not well understood. Conventional finite element models for rolling are highly inefficient, hindering the simulation of multi-layer rolling for large WAAM components. This study aims to identify the most suitable modelling technique for finite element analysis of large WAAM component rolling. Four efficient rolling models were developed, and their efficiency and accuracy were compared with reference to a conventional large-scale rolling model (i.e., control model) for a WAAM built wall. A short-length transient model with fewer elements than the control model was developed to reduce computational time. Accurate predictions of stress and strain and a reduction in computational time by 96.5% were achieved using the short-length model when an implicit method for numerical solution was employed, while similar efficiency but less accurate prediction was obtained when an explicit solution method was adopted. A Eulerian steady-state model was also developed, which was slightly less efficient (95.91% reduction in computational time) but was much less accurate due to unrealistic representation of rolling process. The applicability of a 2D rolling model was also examined and it was found that the 2D model is highly efficient (99.52% time reduction) but less predictive due to the 2D simplification. This study also shows that the rigid roller adopted in the models is beneficial for improving efficiency without sacrificing accuracyItem Open Access Crack path selection at the interface of wrought and wire + arc additive manufactured Ti–6Al–4V(Elsevier, 2016-05-12) Zhang, Jikui; Zhang, Xiang; Wang, Xueyuan; Ding, Jialuo; Traoré, Yéli; Paddea, Sanjooram; Williams, Stewart W.Crack propagation deviation tendency in specimens containing an interface between wrought alloy substrate and Wire + Arc Additive Manufacture (WAAM) built Ti–6Al–4V is investigated from the viewpoints of microstructure, residual stress and bi-material system. It is found that a crack initiated at the interface tends to grow into the substrate that has equiaxed microstructure and lower resistance to fatigue crack propagation. Experimental observations are interpreted by finite element modelling of the effects of residual stress and mechanical property mismatch between the WAAM and wrought alloy. Residual stresses retained in the compact tension specimens are evaluated based on measured residual stress in the initial WAAM built wall. Cracks perpendicular to the interface kept a straight path owing to the symmetrical residual stress distribution. In this case the tangential stress in bi-material model is also symmetric and has the maximum value at the initial crack plane. In contrast, cracks parallel to the interface are inclined to grow towards the substrate due to the mode II (or sliding mode) stress intensity factor caused by the asymmetric residual stress field. Asymmetric tangential stress in the bi-material model also contributes to the observed crack deviation trend according to the maximum tangential stress criterion.Item Open Access Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy(Elsevier, 2019-01-28) Biswal, Romali; Zhang, Xiang; Syed, Abdul Khadar; Awd, Mustafa; Ding, Jialuo; Walther, Frank; Williams, Stewart W.This study was aimed at investigating the effect of internal porosity on the fatigue strength of wire + arc additive manufactured titanium alloy (WAAM Ti-6Al-4V). Unlike similar titanium alloys built by the powder bed fusion processes, WAAM Ti-6Al-4V seldom contains gas pores. However, feedstock may get contaminated that may cause pores of considerable size in the built materials. Two types of specimens were tested: (1) control group without porosity referred to as reference specimens; (2) designed porosity group using contaminated wires to build the specimen gauge section, referred to as porosity specimens. Test results have shown that static strength of the two groups was comparable, but the elongation in porosity group was reduced by 60% and its fatigue strength was 33% lower than the control group. The stress intensity factor range of the crack initiating pore calculated by Murakami’s approach has provided good correlation with the fatigue life. The kink point on the data fitting curve corresponds well with the threshold value of the stress intensity factor range found in the literature. For predicting the fatigue limit, a modified Kitagawa-Takahashi diagram was proposed consisting of three regions depending on porosity size. Critical pore diameter was found to be about 100 µm.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 Data supporting: 'Modelling and optimising hybrid process of wire arc additive manufacturing and high-pressure rolling'(Cranfield University, 2022-10-04 10:54) Gornyakov, Valeriy; Sun, Yongle; Ding, Jialuo; Williams, StewartFigure 7 Predicted distortion of the WAAM part after deactivation of clamps . Figure 8 Longitudinal RS distributions along the vertical path in the symmetry plane for the full-length mechanical models after clamps deactivation, compared to experimental measurements [5]. The flat roller (a) and slotted roller (b) were used in the rolling simulations, and the full-length model was based on the solution mapped from the steady-state region of the reduced-length WAAM + IL rolling model Figure 10 Concurrent evolution of temperature and longitudinal stress (a), as well as the longitudinal PS (b), in the layer 6 during WAAM deposition of layers 6-8 in conjunction with IL rolling using the flat roller. The data were collected at the top of layer 6 in the inspection plane and the rolling phases are highlighted in the yellow shaded areas. Figure 11 Concurrent evolution of temperature and longitudinal stress (a), as well as longitudinal PS (b), in the layer 6 during WAAM deposition of layers 9-11 in conjunction with IL rolling using the flat roller. The data were collected at the top of layer 6 in the inspection plane and the rolling phases are highlighted in the yellow shaded areas. Figure 12 Concurrent evolution of temperature and longitudinal stress (a), as well as longitudinal PS (b), in the layer 6 during WAAM deposition of layers 12-14 in conjunction with IL rolling using the flat roller. The data were collected at the top of layer 6 in the inspection plane and the rolling phases are highlighted in the yellow shaded areas. Figure 13 Concurrent evolution of the longitudinal PS and stress in the layer 9 during WAAM deposition of layers 9-16 in conjunction with IL rolling using the slotted roller. The data were collected at the top of layer 9 in the inspection plane (the slotted roller started rolling on layer 6) and the rolling phases are highlighted in the yellow shaded areas. Figure 18 Evolution of longitudinal PS in the layer 6 during WAAM deposition and stacked 4L rolling with flat roller. The rolling phases are highlighted in the yellow shaded areas.Item Open Access Data supporting: 'Multi-Energy Source (MES) Configuration for Bead Shape Control in Wire-based Directed Energy Deposition (w-DED)'(Cranfield University, 2022-08-31 15:42) Chen, Guangyu; Suder, Wojciech; Williams, Stewart; Ding, Jialuo; Wang, ChongVideo shows the the dynamic changing of the melt pool and highspeed scanning motion of the laser beam.Item Open Access Data supporting: 'Split anode calorimetry for plasma arc energy density measurement with laser calibration'(Cranfield University, 2022-11-23 15:46) Chen, Guangyu; Williams, Stewart; Ding, Jialuo; Suder, Wojciech; Wang, YipengVideo shows the accelarated thermal image when the laser beam traveled acrossed the copper anodes interface.Item Open Access Data supporting: 'Wire based plasma arc and laser hybrid additive manufacture of Ti-6Al-4V'(Cranfield University, 2022-11-23 16:47) Wang, Chong; Suder, Wojciech; Ding, Jialuo; Williams, StewartThese are two supplementary videos for Fig 5, showing different configurations for wire based PTA-laser hybrid additive manufacturing process.Item Open Access Data: Automated interlayer wall height compensation for wire based directed energy deposition additive manufacturing(Cranfield University, 2024-05-08 16:28) Qin, Jian; Vives, Javier; Rajan, Parthiban; Lasisi, Shakirudeen; Wang, Chong; Charrett, Tom; Ding, Jialuo; Williams, Stewart; Hallam, Jonathan; Tatam, RalphExperimental dataset to support the publication. The data includes all the test and measurement records for the experiment.Item Open Access Data: Prediction of electron beam welding penetration depth using machine learning-enhanced computational fluid dynamics modelling(Cranfield University, 2023-10-26 15:38) Yin, Yi; Tian, Yingtao; Ding, Jialuo; Mitchell, Tim; Qin, JianElectron beam probing data: beam characteristics of raidii at welding direction and cross-section direction. Experiments setup: 40–60 kV for the accelerating voltage, 25–45 mA for the beam current, and a welding speed of 500–700 mm/min.Item Open Access Data: Process control methods in cold wire gas metal arc additive manufacturing(Cranfield University, 2023-08-01 10:54) Bento, João; Wang, Chong; Ding, Jialuo; Williams, StewartData supporting the study published with the name: Process control methods in cold wire gas metal arc additive manufacturingItem Open Access Data: Thermo-Capillary-Gravity Bidirectional Modelling for Evaluation and Design of Wire-Based Directed Energy Deposition Additive Manufacturing(Cranfield University, 2023-10-31 11:08) Mosalman Haghighi, Alireza; Ding, Jialuo; Sun, Yongle; Wang, Chong; Williams, StewartIn this study, a thermo-capillary-gravity bidirectional analytical model is developed based on the fundamental governing physics, enabling fast predictions of both w-DED bead geometries and process parameters. A novel method is also proposed to determine the power transfer efficiency and wire melting efficiency defined in the model. In the forward modelling, deposit bead geometries, such as layer height and width, can be predicted for given process parameters and material properties. In the reverse modelling, the outputs of the model are process parameters, including heat source power and travel speed, to achieve the deposit bead geometries as required for a given application. This bidirectional modelling approach is applicable to different w-DED processes, and it has been validated for the deposition of steel walls using plasma transferred arc and cold wire gas metal arc processes. The developed bidirectional analytical model could be used as an efficient and reliable tool for w-DED process evaluation and design.