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Guoliang Qin - One of the best experts on this subject based on the ideXlab platform.
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effect of modified flux on mig arc brazing Fusion Welding of aluminum alloy to steel butt joint
Journal of Materials Processing Technology, 2017Co-Authors: Guoliang QinAbstract:Abstract Pulsed MIG arc brazing-Fusion Welding process was applied to realize the butt joining of galvanized steel and 5052 aluminum alloy with no enclosed slot or groove adopted. A modified flux mixture was developed to improve the butt joint performance. After applying the modified flux, weld appearance became better and the spreadability of filler metal was also greatly improved. During brazing-Fusion Welding process, flux floating on the surface of Welding pool weakened the surface tension between filler metal and Fe and reduced the evaporation of Zn, which both led to the greatly enhanced spreadability. The analysis of intermetallic compounds (IMCs) at brazed interface showed that Fe 3 Al was formed at upper side of steel plate, while Fe 2 Al 5 was formed at other areas with the consideration of its lowest Gibbs free energy under certain temperature range. With modified flux, the tensile strength of the joint could reach up to 120 MPa, which was about 60% of that of 5052 aluminum alloy base metal. From the fractured surface, two different fracture modes were identified, tear fracture and intergranular fracture, which confirmed that joint fractured in a brittle mode. The crack initiated at the front side of brazed interface due to the thicker IMCs layer, then propagated to the surface before the whole joint failed. The improved spreadability of filler metal on the top and back sides of steel plate due to the application of flux, contributed to the improvement of joint strength.
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numerical simulation of large spot laser mig arc brazing Fusion Welding of al alloy to galvanized steel
Journal of Materials Processing Technology, 2015Co-Authors: Xiangmeng Meng, Guoliang QinAbstract:Abstract A finite element model was developed to investigate the thermal process of large spot laser + MIG arc brazing–Fusion Welding. The laser was treated as a Gaussian plane heat source, the MIG arc was performed as a modified double ellipse Gaussian plane heat source, in which the arc distortion was taken into consideration and the overheated droplet was treated as a uniform body heat source. The calculated weld bead geometry and heat-affected width of zinc coating had good agreement with experimental results. The temperature field, especially for the brazed interface, showed non-uniform and asymmetric distribution. The thermal cycles at brazed interface had obvious bimodal characteristic at arc center and laser spot center and the high-temperature zone at the brazed interface was widened duo to the introduction of laser beam compared with conventional MIG brazing–Fusion Welding. A fundamental processing window was determined based on the founded model to satisfy a certain energy condition, in which the Al alloy was fully penetrated and steel plate was not melted.
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numerical simulation on mig arc brazing Fusion Welding of aluminum alloy to galvanized steel plate
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: Guoliang Qin, Xiangmeng MengAbstract:Based on the difference in melting point between aluminum alloy and steel, metal inert gas (MIG) arc brazing-Fusion Welding process was developed to join thin 6013 aluminum alloy plate to galvanized steel plate. A finite element model for lap joint was established to study its thermal process. In modeling, MIG arc was treated as the double ellipse Gaussian plane heat source and the overheated metal droplet was considered as the uniform body heat source. The effects of the zinc coating and the overlap gap were taken into consideration. The brazed seam width and the width of heat-affected zinc coating on the back side of galvanized steel plate were used to validate the calculated results. The results show that the calculated results are in good agreement with experimental results. The calculation results indicate that the temperature is not uniformly distributed in the brazing-Fusion welded joint. There is a great difference in the reaction temperature and time at different positions on the brazed interface. In order to satisfy the energy condition in which aluminum plate is fully penetrated and steel plate is not melted, a corresponding relationship that the Welding current and Welding speed are synchronized to be increased must be followed.
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microstructures and properties of welded joint of aluminum alloy to galvanized steel by nd yag laser mig arc hybrid brazing Fusion Welding
Transactions of Nonferrous Metals Society of China, 2014Co-Authors: Guoliang Qin, S U Yuhu, Shu Jun WangAbstract:Abstract According to the differences in melting point between aluminum alloy and steel, 6013-T4 aluminum alloy was joined to galvanized steel by large spot Nd:YAG laser + MIG arc hybrid brazing-Fusion Welding with ER4043(AlSi5) filler wire. The microstructures and mechanical properties of the brazed–Fusion welded joint were investigated. The joint is divided into two parts of Fusion weld and brazed seam. There is a zinc-rich zone at Fusion weld toe, which consists of α(Al)–Zn solid solution and Al–Zn eutectic. The brazed seam is the Fe–Al intermetallic compounds (IMCs) layer of 2–4 μm in thickness, and the IMCs include FeAl 2 , Fe 2 Al 5 and Fe 4 Al 13 . FeAl 2 and Fe 2 Al 5 are located in the compact reaction layer near the steel side, and Fe 4 Al 13 with tongue shape or sawtooth shape grows towards the Fusion weld. The tensile strength of the joint firstly increases and then decreases as the Welding current and laser power increase, the highest tensile strength can be up to 247.3 MPa, and the fracture usually occurs at Fusion zone of the Fusion weld. The hardness is the highest at the brazed seam because of hard Fe–Al IMCs, and gradually decreases along the Fusion weld and galvanized steel, respectively.
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Microstructures and properties of welded joint of aluminum alloy to galvanized steel by Nd:YAG laser + MIG arc hybrid brazing-Fusion Welding
Transactions of Nonferrous Metals Society of China, 2014Co-Authors: Guoliang Qin, Yuhu Su, Shu Jun WangAbstract:According to the differences in melting point between aluminum alloy and steel, 6013-T4 aluminum alloy was joined to galvanized steel by large spot Nd:YAG laser + MIG arc hybrid brazing-Fusion Welding with ER4043(AlSi5) filler wire. The microstructures and mechanical properties of the brazed–Fusion welded joint were investigated. The joint is divided into two parts of Fusion weld and brazed seam. There is a zinc-rich zone at Fusion weld toe, which consists of α(Al)–Zn solid solution and Al–Zn eutectic. The brazed seam is the Fe–Al intermetallic compounds (IMCs) layer of 2–4 μm in thickness, and the IMCs include FeAl2, Fe2Al5 and Fe4Al13. FeAl2 and Fe2Al5 are located in the compact reaction layer near the steel side, and Fe4Al13 with tongue shape or sawtooth shape grows towards the Fusion weld. The tensile strength of the joint firstly increases and then decreases as the Welding current and laser power increase, the highest tensile strength can be up to 247.3 MPa, and the fracture usually occurs at Fusion zone of the Fusion weld. The hardness is the highest at the brazed seam because of hard Fe–Al IMCs, and gradually decreases along the Fusion weld and galvanized steel, respectively.
J. M. Lefebvre - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of the non-isothermal Fusion-Welding of unlike ethylene copolymers over a wide crystallinity range
Polymer, 2013Co-Authors: C. Frederix, P. Beauchene, Roland Seguela, J. M. LefebvreAbstract:Abstract The non-isothermal Fusion-Welding of unlike polyethylene materials has been studied using three linear ethylene copolymers covering the crystallinity range 16–77% and displaying partial miscibility of the binary blends. Welding was carried out by putting into intimate contact under slight pressure the molten surfaces of two flat beams quickly heated up far above the melting point by means of infrared radiations. Particular attention was paid to the wetting of the beams using ultrasonic measurements. The interface adhesion strength was determined by means of double cantilever beam method. Homo- as well as hetero-Welding proved to be highly efficient for only a few seconds of contact of the two beams in the molten state. The critical strain energy release rate of the interface reached values G1C ≥ 6 kJ/m2 for contact time less than 10 s. The time window of efficient Welding proved to be intermediate between the number-average and weight-average values of the terminal relaxation time according to melt rheology. This is consistent with Wool's criterion assuming that perfect self-Welding of amorphous polymer requires reptation of chains over their whole length through the interface. The longer chains yet seemed not to be able to achieve complete tube renewal during the experimental time window of efficient Welding. It is suggested that the reptation of the shortest chains contributes to the restoration of the entanglement network of the longest chains within a time scale much shorter than the reptation time of the latter ones. The surprising efficiency of hetero-Welding in agreement with Wool's criterion is attributed to the interfacial miscibility of the unlike copolymers. The concomitant role of cocrystallization in the process is pointed out for such semi-crystalline polymers.
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Kinetics of the non-isothermal Fusion-Welding of unlike ethylene copolymers over a wide crystallinity range
Polymer, 2013Co-Authors: C. Frederix, P. Beauchene, Roland Seguela, J. M. LefebvreAbstract:The non-isothermal Fusion-Welding of unlike polyethylene materials has been studied using three linear ethylene copolymers covering the crystallinity range 16-77% and displaying partial miscibility of the binary blends. Welding was carried out by putting into intimate contact under slight pressure the molten surfaces of two flat beams quickly heated up far above the melting point by means of infrared radiations. Particular attention was paid to the wetting of the beams using ultrasonic measurements. The interface adhesion strength was determined by means of double cantilever beam method. Homo- as well as hetero-Welding proved to be highly efficient for only a few seconds of contact of the two beams in the molten state. The critical strain energy release rate of the interface reached values G(1C) >= 6 kJ/m(2) for contact time less than 10 s. The time window of efficient Welding proved to be intermediate between the number-average and weight-average values of the terminal relaxation time according to melt rheology. This is consistent with Wool's criterion assuming that perfect self-Welding of amorphous polymer requires reptation of chains over their whole length through the interface. The longer chains yet seemed not to be able to achieve complete tube renewal during the experimental time window of efficient Welding. It is suggested that the reptation of the shortest chains contributes to the restoration of the entanglement network of the longest chains within a time scale much shorter than the reptation time of the latter ones. The surprising efficiency of hetero-Welding in agreement with Wool's criterion is attributed to the interfacial miscibility of the unlike copolymers. The concomitant role of cocrystallization in the process is pointed out for such semi-crystalline polymers. (C) 2013 Elsevier Ltd. All rights reserved.
Shuhai Chen - One of the best experts on this subject based on the ideXlab platform.
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joining mechanism of ti al dissimilar alloys during laser Welding brazing process
Journal of Alloys and Compounds, 2011Co-Authors: Shuhai Chen, Liqun Li, Yanbin Chen, Jihua HuangAbstract:Abstract Joining mechanism of Ti/Al dissimilar alloys was investigated during laser Welding–brazing process with automated wire feed. The microstructures of Fusion Welding and brazing zones were analysed in details by transmission electron microscope (TEM). It was found that microstructures of Fusion Welding zone consist of α-Al grains and ternary near-eutectic structure with α-Al, Si and Mg 2 Si. Interfacial reaction layers of brazing joint were composed of α-Ti, nanosize granular Ti 7 Al 5 Si 12 and serration-shaped TiAl 3 . For the first time, apparent stacking fault structure in intermetallic phase TiAl 3 was found when the thickness of the reaction layer was very thin (approximately less than 1 μm). Furthermore, crystallization behavior of Fusion zone and mechanism of interfacial reaction were discussed in details.
Hector Basoalto - One of the best experts on this subject based on the ideXlab platform.
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Modelling of thermal fluid dynamics for Fusion Welding
Journal of Materials Processing Technology, 2018Co-Authors: Chinnapat Panwisawas, Yogesh Sovani, Richard Turner, Jeffery Brooks, Hector Basoalto, Isabelle ChoquetAbstract:Abstract A fluid dynamics approach to modelling of Fusion Welding in titanium alloys is proposed. The model considers the temporal and spatial evolution of liquid metal/gas interface to capture the transient physical effects during the heat source–material interaction of a Fusion Welding process. Melting and vaporisation have been considered through simulation of all interfacial phenomena such as surface tension, Marangoni force and recoil pressure. The evolution of the metallic (solid and liquid) and gaseous phases which are induced by the process enables the formation of the keyhole, keyhole dynamics, and the fully developed weld pool geometry. This enables the likelihood of fluid flow-induced porosity to be predicted. These features are all a function of process parameters and formulated as time-dependent phenomena. The proposed modelling framework can be utilised as a simulation tool to further develop understanding of defect formation such as weld-induced porosity for a particular Fusion Welding application. The modelling results are qualitatively compared with available experimental information.
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keyhole formation and thermal fluid flow induced porosity during laser Fusion Welding in titanium alloys experimental and modelling
Acta Materialia, 2017Co-Authors: Chinnapat Panwisawas, Richard Turner, Jeffery Brooks, Bama Perumal, Mark R Ward, Nathanael Turner, Hector BasoaltoAbstract:High energy-density beam Welding, such as electron beam or laser Welding, has found a number of industrial applications for clean, high-integrity welds. The deeply penetrating nature of the joints is enabled by the formation of metal vapour which creates a narrow Fusion zone known as a “keyhole”. However the formation of the keyhole and the associated keyhole dynamics, when using a moving laser heat source, requires further research as they are not fully understood. Porosity, which is one of a number of process induced phenomena related to the thermal fluid dynamics, can form during beam Welding processes. The presence of porosity within a welded structure, inherited from the Fusion Welding operation, degrades the mechanical properties of components during service such as fatigue life. In this study, a physics-based model for keyhole Welding including heat transfer, fluid flow and interfacial interactions has been used to simulate keyhole and porosity formation during laser Welding of Ti-6Al-4V titanium alloy. The modelling suggests that keyhole formation and the time taken to achieve keyhole penetration can be predicted, and it is important to consider the thermal fluid flow at the melting front as this dictates the evolution of the Fusion zone. Processing induced porosity is significant when the Fusion zone is only partially penetrating through the thickness of the material. The modelling results are compared with high speed camera imaging and measurements of porosity from welded samples using X-ray computed tomography, radiography and optical micrographs. These are used to provide a better understanding of the relationship between process parameters, component microstructure and weld integrity.
C. Frederix - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of the non-isothermal Fusion-Welding of unlike ethylene copolymers over a wide crystallinity range
Polymer, 2013Co-Authors: C. Frederix, P. Beauchene, Roland Seguela, J. M. LefebvreAbstract:Abstract The non-isothermal Fusion-Welding of unlike polyethylene materials has been studied using three linear ethylene copolymers covering the crystallinity range 16–77% and displaying partial miscibility of the binary blends. Welding was carried out by putting into intimate contact under slight pressure the molten surfaces of two flat beams quickly heated up far above the melting point by means of infrared radiations. Particular attention was paid to the wetting of the beams using ultrasonic measurements. The interface adhesion strength was determined by means of double cantilever beam method. Homo- as well as hetero-Welding proved to be highly efficient for only a few seconds of contact of the two beams in the molten state. The critical strain energy release rate of the interface reached values G1C ≥ 6 kJ/m2 for contact time less than 10 s. The time window of efficient Welding proved to be intermediate between the number-average and weight-average values of the terminal relaxation time according to melt rheology. This is consistent with Wool's criterion assuming that perfect self-Welding of amorphous polymer requires reptation of chains over their whole length through the interface. The longer chains yet seemed not to be able to achieve complete tube renewal during the experimental time window of efficient Welding. It is suggested that the reptation of the shortest chains contributes to the restoration of the entanglement network of the longest chains within a time scale much shorter than the reptation time of the latter ones. The surprising efficiency of hetero-Welding in agreement with Wool's criterion is attributed to the interfacial miscibility of the unlike copolymers. The concomitant role of cocrystallization in the process is pointed out for such semi-crystalline polymers.
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Kinetics of the non-isothermal Fusion-Welding of unlike ethylene copolymers over a wide crystallinity range
Polymer, 2013Co-Authors: C. Frederix, P. Beauchene, Roland Seguela, J. M. LefebvreAbstract:The non-isothermal Fusion-Welding of unlike polyethylene materials has been studied using three linear ethylene copolymers covering the crystallinity range 16-77% and displaying partial miscibility of the binary blends. Welding was carried out by putting into intimate contact under slight pressure the molten surfaces of two flat beams quickly heated up far above the melting point by means of infrared radiations. Particular attention was paid to the wetting of the beams using ultrasonic measurements. The interface adhesion strength was determined by means of double cantilever beam method. Homo- as well as hetero-Welding proved to be highly efficient for only a few seconds of contact of the two beams in the molten state. The critical strain energy release rate of the interface reached values G(1C) >= 6 kJ/m(2) for contact time less than 10 s. The time window of efficient Welding proved to be intermediate between the number-average and weight-average values of the terminal relaxation time according to melt rheology. This is consistent with Wool's criterion assuming that perfect self-Welding of amorphous polymer requires reptation of chains over their whole length through the interface. The longer chains yet seemed not to be able to achieve complete tube renewal during the experimental time window of efficient Welding. It is suggested that the reptation of the shortest chains contributes to the restoration of the entanglement network of the longest chains within a time scale much shorter than the reptation time of the latter ones. The surprising efficiency of hetero-Welding in agreement with Wool's criterion is attributed to the interfacial miscibility of the unlike copolymers. The concomitant role of cocrystallization in the process is pointed out for such semi-crystalline polymers. (C) 2013 Elsevier Ltd. All rights reserved.
