Browsing by Author "Suder, Wojciech"
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Item Open Access Assessment of the laser beam welding of galvanized car body steel with an additional organic protective layer(MDPI, 2023-01-10) Górka, Jacek; Suder, Wojciech; Kciuk, Monika; Stano, SebastianThis study discusses the effect of laser beam welding parameters on the structure, mechanical properties and corrosion resistance of 1.2 mm thick galvanized sheets made of low-carbon steel DC04 provided with a ZE36/36 GardoprotectOC2BU organic coating. The test laser beam butt welded joints were made without the filler metal, using a variable welding rate, where linear welding energy was restricted within the range of 30 J/mm to 90 J/mm. The joints were subjected to non-destructive tests, destructive tests and corrosion resistance tests. The tests revealed the possibility of making joints meeting the criteria specified in the ISO 15614-11 standard. Regardless of the value of linear welding energy applied in the process, all the joints were characterised by high mechanical and plastic properties. It was noticed that an increase in linear welding energy from 30 J/mm to 90 J/mm was accompanied by the widening of the weld and that of the heat-affected zone (HAZ). In addition, an increase in linear welding energy was accompanied by a decrease in the maximum weld hardness to approximately 250 HV0.2. In the HAZ, hardness was restricted within the range of 190 HV0.2 to 230 HV0.2 and decreased along with increasing linear welding energy. In the static tensile test, regardless of the value of linear welding energy, the test specimen ruptured in the base material. In the bend test, regardless of the value of linear welding energy, a bend angle of 180° was obtained without partial tear or scratches; unit elongation was restricted within the range of 29% to 42%. The electrochemical tests and experiments performed in the salt spray chamber revealed the very high effectiveness of the corrosion protections against aggressive chloride ions.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 Characterising and modelling plasma transferred arc for additive manufacturing(Elsevier, 2025-05-15) Chen, Guangyu; Sun, Yongle; Wang, Chong; Ding, Jialuo; Suder, Wojciech; Li, Zhiyong; Williams, Stewart W.The thermal characteristics of a plasma transferred arc (PTA) and its mathematical representation are primary considerations when designing and modelling PTA-based wire arc additive manufacturing (WAAM). However, most of the currently used PTA thermal characteristics are derived from welding processes, which are not directly applicable to WAAM. In this study, the power density distribution, arc diameter and arc efficiency of PTA in the WAAM process were measured using the split anode calorimetry (SAC) method. The effects of key process parameters, including current intensity, plasma gas composition, plasma gas flow rate, and arc length, on the PTA power profile were systematically examined. The results show that for a typical PTA used in WAAM, the arc diameter ranged from 9.6 mm to 10.8 mm, with an arc efficiency of approximately 60 % within the tested parameter range. The PTA power becomes more concentrated as power density increases with higher current intensity and plasma gas flow rates. Additionally, a softer plasma was achieved by increasing helium content in the plasma gas or by using a longer nozzle-to-workpiece standoff distance, both of which are beneficial for avoiding keyhole defects. To accurately represent PTA power distribution, a binomial Gaussian heat source model was proposed, which captures the details of the arc power profile with a high accuracy of over 99.94 %, outperforming the conventional monomial Gaussian heat source model. The PTA calorimetry characterisation and the proposed binomial Gaussian model can be useful in establishing a better understanding of the PTA power profile and enhancing process control for high-precision WAAM.Item Open Access Comparison of continuous and pulsed wave lasers in keyhole welding of stainless‑steel to aluminium(Springer, 2021-10-31) Coroado, Julio; Ganguly, Supriyo; Williams, Stewart; Suder, Wojciech; Meco, Sonia; Pardal, GoncaloA continuous wave (CW) and a nanosecond pulsed wave (PW) lasers were used to join 1-mm thick sheets of SS304L (SS) austenitic stainless-steel to AA5251 (Al) aluminium alloy in an overlap joint configuration. The weld shape (penetration depth and width), intermetallic compounds concentration, weld quality (cracking and porosity) and mechanical strength were correlated with the process energy and compared between each laser temporal mode. Successful CW joints were produced with the SS sheet on top of the Al, but the opposite configuration revealed to be impossible for the range of parameters tested. The PW joints were successful with the Al sheet on top of SS, but all the joints cracked at the interface when the opposite configuration was used. The mechanical tests showed that even though it is possible to achieve higher tensile shear load in CW welds due to the larger bonding area, the tensile shear strength revealed to be almost 5 × higher for PW welds at similar applied energy.Item Open Access Comparison of joining efficiency and residual stresses in laser and laser hybrid welding(2011-04-01T00:00:00Z) Suder, Wojciech; Ganguly, Supriyo; Williams, Stewart W.; Paradowska, A. M.; Colegrove, Paul A.Laser welding is a high energy density process, which can produce welds with less energy input and thereby lower residual stress generation compared to arc welding processes. However, the narrow beam dimension makes it extremely sensitive in terms of fit up tolerance. This causes a problem in achieving high quality welds. Laser with arc hybrid process overcomes such issues. In this paper, longitudinal residual strains were compared for autogenous laser welding and laser/TIG hybrid processes. Joining efficiency, which is defined by the penetration depth achieved per unit of energy input, was correlated with the residual strain generation. It has been shown that to achieve a specific penetration depth, there is an optimum welding condition for each of the welding processes, which will give minimum tensile residual stress generation. The results imply that for the same penetration depth, hybrid process resulted in similar to 50% higher tensile longitudinal domain compared to autogenous laser.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 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: '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: Penetration and mixing of filler wire in hybrid laser welding(Cranfield University, 2023-08-09 16:10) Suder, WojciechThis file contains all dataset from the above paperItem Open Access Development of hybrid laser arc welding process for automotive structural applications.(Cranfield University, 2019-09) Jeyakandan, Subramanian; Ganguly, Supriyo; Suder, WojciechIn today’s world, two-wheelers (Motorcycles and Scooters) have become an indispensable part of people’s lives. Customers are demanding high quality product with superior performance of the vehicle. Frame is one of the safety critical part of a two-wheeler which highly contributes to the functional and aesthetic quality of the vehicle. Predominantly, gas metal arc welding (GMAW) process is being used for the manufacturing of frame. Limited depth of penetration and low welding speed of GMAW process significantly hinders the quality and productivity. Moreover, high heat input of this process consequently results in larger distortion. High fusion zone and HAZ area leads to degradation of material properties. Better structural integrity and consistent frame dimensions are required to meet the functional and finish quality requirements of a vehicle. Hence, advanced laser welding processes were investigated as an alternative method to GMAW process in the facets of productivity, heat input, weld bead geometry, aesthetic quality, gap bridgeability and distortion. Typically two- wheeler frame is made of low carbon steel. Thus low carbon steel of S275 grade was used for the evaluation. The outcomes were compared with existing GMAW process to quantify the benefits of laser welding. High power density of autogenous laser welding (ALW) process provided deeper penetration with significant improvement in productivity. When compared with GMAW process, productivity was improved by a factor of 8 times in 2 mm and 4 mm thick plates whereas 3 times improved productivity was achieved in 8 mm thick plates with complete penetration. However, lack of reinforcement and restricted part fit-up tolerance were found to be the critical limitations of ALW process. On the other hand, addition of filler metal using a GMAW arc in hybrid laser arc welding process (HLAW) ensured a better weld geometry and improved gap bridgeability of the process. Moreover, it was provided deeper penetration and significant improvement in productivity which is comparable to ALW process and far higher than GMAW process. Both HLAW and ALW processes produced ~75% and ~85% less distortion than GMAW process respectively. Moreover, HLAW process improved the productivity with considerably less increase in hardness than ALW process. For instance, in 2 mm thick material, productivity was improved by 8 times than GMAW process with 55% and 17% increase in average fusion zone hardness in ALW and HLAW processes respectively. Moreover, substantial reduction in fusion zone and HAZ width was obtained in both HLAW and ALW processes. In mechanical strength standpoint, all three welding processes produced weld region stronger than base material. Therefore, fracture was occurred in the base material during tensile test. Overall, HLAW process combines the advantages of both individual processes and eliminates the limitations of them. Hence, hybrid laser arc welding process can be considered as the future of welding in the automobile sector.Item Open Access Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle(EDP Sciences, 2020-11-05) Demirorer, Mete; Suder, Wojciech; Ganguly, Supriyo; Hogg, Simon; Naeem, HassamAn innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic coolingItem Open Access Effect of beam shape and spatial energy distribution on weld bead geometry in conduction welding(Cranfield University, 2019-04-25 13:01) Suder, WojciechData used in the corresponding paper (link below).Item Open Access Effect of beam shape and spatial energy distribution on weld bead geometry in conduction welding(Elsevier, 2019-04-29) Suder, Wojciech; Williams, Stewart W.; Ayoola, Wasiu A.The size of a projected beam onto a workpiece and its intensity distribution profile defines the response of the material to the applied laser heat. This means that not only the processing parameters, but also the optical set-up and process tools define the process and the resulting weld profile. In high power laser delivery systems the beam propagation characteristics of the laser beam can vary during processing. A change of the focal distance, for instance, alters the spot size projected on the workpiece as well as its intensity distribution. Some dynamic optical systems can also change the shape of the projected beam. Galvo-scanners induce a small distortion to the projected beam from circular to elliptical when the mirrors deflect the beam across the working domain. This continuous change of the spatial energy distribution may affect the process stability and material response locally. This work examines the influence of changing the shape of the projected beam and its energy distribution on the weld bead profile in conduction laser welding, which is also relevant to laser cladding and additive manufacture. It has been found that for the same optical set-up and system parameters, different bead profiles can be obtained with different degree of distortion of the beam profile. In addition, different intensity distribution profiles led to different penetration depths for the same nominal beam diameter and energy density due to the difference in peak intensity.Item Open Access Effect of different shielding conditions, thermal cycles and post- deposition treatments on melting behaviour and mechanical properties of additively built components(Cranfield University, 2023-02) Cabellero Ramos, Armando Enrique; Suder, Wojciech; Williams, Stewart W.Additive manufacturing (AM) offers many advantages as compared to traditional manufacturing routes such as machining and forging thanks to its capability of reducing lead times, enhanced design flexibility and material saving. However, many challenges still must be overcome before this relatively novel technology can be implemented in the production of critical components. It is known that to achieve satisfactory performance of additively built parts it is important to ensure the absence of volumetric defects such as pores and the presence of a suitable microstructure that will offer the required mechanical properties. Many process variables such as shielding gas composition, thermal histories and post- deposition heat treatments can control these aspects. This work, focuses on the role of shielding gas composition on melting behaviour during laser powder bed fusion and on the microstructural evolution of stainless steel and the effect of different thermal cycles on two age hardenable alloys during Wire and Arc Additive Manufacture deposition. The objective of this thesis was to investigate how critical these variables can be in achieving the desired properties of 3D- printed parts for specific processes and alloys. The material interaction with the AM heat source is a complex phenomenon and for this reason, a wide range of advanced characterisation techniques were used in this work including high- speed imaging, scanning electron microscopy, chemical analysis, fractography, electron back-scattered diffraction, among others. It was possible to conclude that shielding gas composition is key to ensuring stability during laser powder melting of stainless steel. Additionally, the sensitivity of the microstructural features to different thermal cycles inherent to the Wire and Arc Additive Manufacture (WAAM) process was established for two age-hardenable alloys, 17-4PH (martensitic stainless steel) and Ti-5553 (near β titanium alloy). The effectiveness of standard post-deposition heat treatments to optimise the final mechanical properties of these two alloys was also identified. Finally, it was also possible to find how sensitive the developed microstructure of WAAM Ti-6Al-4V is to different levels of interstitial elements concentration. This is of great use for further applications as the incorporation of oxygen and its potential adverse effect on mechanical performance remains one of the main concerns for the processing of titanium alloys.Item Open Access Effect of high-pressure rolling followed by laser processing on mechanical properties, microstructure and residual stress distribution in multi-pass welds of 304L stainless steel(Springer, 2016-01-18) Sule, Jibrin; Ganguly, Supriyo; Suder, Wojciech; Pirling, ThiloMulti-pass fusion welding by a filler material (wire) is normally carried out to join thick steel sections used in most engineering applications. Multiple thermal cycles from a multi-pass weld resulted in a variable distribution of residual stress field across the weld and through the thickness. Presence of tensile residual stresses can be detrimental to the integrity and the service behaviour of the welded joint. In addition to a complex distribution of residual stress state, multi-pass welds also form dendritic grain structure, which are repeatedly heated, resulting in segregation of alloying elements. In this research, microstructural refinement with modification of residual stress state was attempted by applying post-weld cold rolling followed by laser processing and then cold rolling. The residual stress was determined non-destructively by using neutron diffraction. Post-weld cold rolling followed by laser processing was carried out to induce recrystallization of the cold rolled grains. Microstructural characterisation indicates a significant grain refinement near the capping pass. However, post-weld cold rolling followed by laser processing reinstates the lock-in stress. In this study, it was demonstrated that a complete recrystallized microstructure with compressive state of stress can be formed when a further cold rolling is applied on the laser processed, recrystallized microstructure.Item Open Access Effect of shielding conditions on bead profile and melting behaviour in laser powder bed fusion additive manufacturing(Elsevier, 2020-05-26) Caballero, Armando; Suder, Wojciech; Chen, Xin; Pardal, Goncalo; Williams, Stewart W.A series of experiments were performed using a 500 W continuous wave fibre laser on a single powder bed layer using different processing variables. The aim was to investigate the effect of different shielding conditions on melting behaviour and bead profile in laser powder bed fusion (PBF). Through high-speed imaging, it was found that under an argon atmosphere a strong plasma plume is generated from the meltpool. Laser beam-plasma plume interactions caused strong instabilities during melting, including laser wandering, track instability and continuous fluctuations between melting regimes (conduction and keyhole). Hence, it was not possible to control the profile of the melted tracks under this condition. By using a helium atmosphere, a smaller plasma was obtained, reducing the disruptions caused by laser-plasma interactions. This led to a stable melting regime that allowed control of the melt bead profile. This condition was used to study the effect of laser-material fundamental interaction parameters on the bead geometry in powder bed melting. It was found that during melting of single tracks, the dominant regime of melting is conduction for the range of parameters tested. Penetration and melt width were found to increase with increasing energy density. For longer interaction times, melt widths were found to be up to ten times the size of the beam diameter used. Fluid flow modelling showed that this is due to strong melt flow as consequence of surface tension gradients generated by very high temperature gradientsItem Open Access 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, WojciechThe 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 producedItem Open Access The effect of wire size on high deposition rate wire and plasma arc additive manufacture of Ti-6Al-4V(Elsevier, 2021-02) Wang, Chong; Suder, Wojciech; Ding, Jialuo; Williams, StewartWire + arc additive manufacture (WAAM) is suitable for building large-scale components with high deposition rate. However, in order to further increase the deposition rate of Ti-6Al-4V to improve productivity and reduce manufacture costs without significantly compromising the quality, some fundamental process characteristics need to be investigated. In this paper, the effect of wire size on the limitation of deposition rate and bead shape in plasma arc additive manufacture was studied along with the process tolerance and melting characteristics, such as the effect of current and nozzle size on keyhole behaviour and the effect of wire feeding position on deposition process. The results show that with the same heat input the deposition rate increases linearly with the wire size due to the increasing melting efficiency. The bead geometry obtained with a thinner wire has a higher aspect ratio, which can be attributed to the difference in the distribution of the energy between wire and workpiece. The likelihood of keyhole increases with increasing current and decreasing nozzle size, and it can be mitigated by using thicker wires. The wire feeding position plays a significant role in determining the metal transfer mode, which has a great impact on the bead shape and process stability. Also, as the deposition rate changes thin wire is more sensitive to wire feeding position than thick wire in terms of metal transfer behaviour
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