Metals

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2 pages, 168 KiB

Open AccessEditorial

Laser Welding

by J. P. Oliveira and Zhi Zeng

Metals 2019, 9(1), 69; https://doi.org/10.3390/met9010069 - 11 Jan 2019

Cited by 3 | Viewed by 2770

Abstract

Welding technologies are critical to most relevant engineering applications [...] Full article

(This article belongs to the Special Issue Laser Welding)

Research

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12 pages, 6407 KiB

Open AccessArticle

Accurate Prediction of the Weld Bead Characteristic in Laser Keyhole Welding Based on the Stochastic Kriging Model

by Xiongfeng Ruan, Qi Zhou, Leshi Shu, Jiexiang Hu and Longchao Cao

Metals 2018, 8(7), 486; https://doi.org/10.3390/met8070486 - 25 Jun 2018

Cited by 13 | Viewed by 4469

Abstract

As an important index of weld quality, the weld bead geometry is closely related to the welding process parameters (WPP). Therefore, it is crucial to establish the relationships between the WPP and weld bead shape to serve as an indicator of the weld [...] Read more.

As an important index of weld quality, the weld bead geometry is closely related to the welding process parameters (WPP). Therefore, it is crucial to establish the relationships between the WPP and weld bead shape to serve as an indicator of the weld quality. However, it is difficult to predict the weld bead shape accurately due to uncertainty. In this paper, laser keyhole welding (LKW) experiments are conducted on 2205 stainless steel at sample points generated by the optimal Latin hypercube sampling (OLHS). Then the relationships between WPP and weld width (WW) are constructed using stochastic kriging model (SKM), considering the randomness of the welding process. To verify the effectiveness of the SKM, two validation approaches, the additional experiments validation and k-fold cross-validation, are used to compare the prediction performance of SKM and the traditional kriging model. SKM is superior to the kriging model at the whole five additional test points with smaller relative error. As to k-fold cross-validation, SKM provides a smaller root mean square error at four in five groups of the data. In addition, SKM can provide the variations of the entire weld bead shape. Overall, the SKM is very prominent in predicting the weld bead shape, considering fluctuations of WPP. Full article

(This article belongs to the Special Issue Laser Welding)

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15 pages, 2237 KiB

Open AccessArticle

3D Multiphysical Modelling of Fluid Dynamics and Mass Transfer in Laser Welding of Dissimilar Materials

by Jiazhou Wu, Hua Zhang, Yan Feng and Bingbing Luo

Metals 2018, 8(6), 443; https://doi.org/10.3390/met8060443 - 11 Jun 2018

Cited by 25 | Viewed by 5788

Abstract

A three-dimensional multiphysical transient model was developed to investigate keyhole formation, weld pool dynamics, and mass transfer in laser welding of dissimilar materials. The coupling of heat transfer, fluid flow, keyhole free surface evolution, and solute diffusion between dissimilar metals was simulated. The [...] Read more.

A three-dimensional multiphysical transient model was developed to investigate keyhole formation, weld pool dynamics, and mass transfer in laser welding of dissimilar materials. The coupling of heat transfer, fluid flow, keyhole free surface evolution, and solute diffusion between dissimilar metals was simulated. The adaptive heat source model was used to trace the change of keyhole shape, and the Rayleigh scattering of the laser beam was considered. The keyhole wall was calculated using the fluid volume equation, primarily considering the recoil pressure induced by metal evaporation, surface tension, and hydrostatic pressure. Fluid flow, diffusion, and keyhole formation were considered simultaneously in mass transport processes. Welding experiments of 304L stainless steel and industrial pure titanium TA2 were performed to verify the simulation results. It is shown that spatters are shaped during the welding process. The thickness of the intermetallic reaction layer between the two metals and the diffusion of elements in the weld are calculated, which are important criteria for welding quality. The simulation results correspond well with the experimental results. Full article

(This article belongs to the Special Issue Laser Welding)

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15 pages, 18628 KiB

Open AccessArticle

Study on the Size Effects of H-Shaped Fusion Zone of Fiber Laser Welded AZ31 Joint

by Guang-Feng Lu, Lin-Jie Zhang, Yi Pei, Jie Ning and Jian-Xun Zhang

Metals 2018, 8(4), 198; https://doi.org/10.3390/met8040198 - 21 Mar 2018

Cited by 12 | Viewed by 4233

Abstract

There are two kinds of typical cross-section profiles for the fusion zone (FZ) of a laser welded thin section joint, i.e., a V-shaped cross-section and an H-shaped cross-section. Previous researches indicated that tensile strength of the V-shaped joint was lower than that of [...] Read more.

There are two kinds of typical cross-section profiles for the fusion zone (FZ) of a laser welded thin section joint, i.e., a V-shaped cross-section and an H-shaped cross-section. Previous researches indicated that tensile strength of the V-shaped joint was lower than that of the H-shaped one due to the greater heterogeneity of strain distribution on the V-shaped joint during tensile process. In this work, impacts of the aspect ratio of FZ on the mechanical properties of laser welded thin section joints with an H-shaped cross-section profile were investigated. Welding conditions corresponding to two typical H-shaped joints (i.e., W_narrower with a narrower FZ, and W_wider with a wider FZ) were decided through a laser welding orthogonal experimental plan. Then, the microstructure and properties of both joints were examined and compared. The results show that the tensile strength of joint W_narrower and joint W_wider was about 72% and 80.9% that of the base metal, respectively. Both joints fractured in the FZ during tensile processes. The low-cycle fatigue life of the base metal, the joint W_narrower and the joint W_wider were 3377.5 cycles, 2825 cycles and 3155.3 cycles, respectively. By using high-speed imaging, it was found that the fatigue crack of joint W_narrower initiated and propagated inside the fusion zone, while the fatigue crack of the joint W_wider initiated at the edge of the base metal and propagated for a distance within the base metal before entering into the fusion zone. This work promoted our understanding about the influence of the weld bead shape on the properties of laser welded thin section joints. Full article

(This article belongs to the Special Issue Laser Welding)

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15 pages, 5536 KiB

Open AccessArticle

Microstructure and Properties of Hybrid Laser Arc Welded Joints (Laser Beam-MAG) in Thermo-Mechanical Control Processed S700MC Steel

by Jacek Górka and Sebastian Stano

Metals 2018, 8(2), 132; https://doi.org/10.3390/met8020132 - 15 Feb 2018

Cited by 31 | Viewed by 7178

Abstract

The article presents the microstructure and properties of joints welded using the Hybrid Laser Arc Welding (HLAW) method laser beam-Metal Active Gas (MAG). The joints were made of 10-mm-thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) and characterised by a high [...] Read more.

The article presents the microstructure and properties of joints welded using the Hybrid Laser Arc Welding (HLAW) method laser beam-Metal Active Gas (MAG). The joints were made of 10-mm-thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) and characterised by a high yield point. In addition, the welding process involved the use of solid wire GMn4Ni1.5CrMo having a diameter of 1.2 mm. Non-destructive tests involving the joints made it possible to classify the joints as representing quality level B in accordance with the ISO 12932 standard. Destructive tests of the joints revealed that the joints were characterised by tensile strength similar to that of the base material. The hybrid welding (laser beam-MAG) of steel S700MC enabled the obtainment of good plastic properties of welded joints. In each area of the welded joints, the toughness values satisfied the criteria related to the minimum allowed toughness value. Tests involving the use of a transmission electron microscope and performed in the weld area revealed the decay of the precipitation hardening effect (i.e., the lack of precipitates having a size of several nm) and the presence of coagulated titanium-niobium precipitates having a size of 100 nm, restricting the growth of recrystallised austenite grains, as well as of spherical stable TiO precipitates (200 nm) responsible for the nucleation of ferrite inside austenite grains (significantly improving the plastic properties of joints). The tests demonstrated that it is possible to make welded joints satisfying quality-related requirements referred to in ISO 15614-14. Full article

(This article belongs to the Special Issue Laser Welding)

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7465 KiB

Open AccessArticle

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

by Ghusoon Ridha Mohammed, Mahadzir Ishak, Syarifah Nur Aqida Syed Ahmad and Hassan Abdulrssoul Abdulhadi

Metals 2017, 7(12), 546; https://doi.org/10.3390/met7120546 - 6 Dec 2017

Cited by 25 | Viewed by 8748

Abstract

In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was [...] Read more.

In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was studied by checking the width and depth of the welds after each round of welding parameters combination. The weld bead dimensions and microstructural progression of the weld joints were observed microscopically. Finally, the full penetration specimens were subjected to tensile tests, which were coupled with the analysis of the fracture surfaces. From the results, combination of the selected weld parameters resulted in robust weldments with similar features to those of duplex and austenitic weld metals. The weld depth and width were found to increase proportionally to the laser power. Furthermore, the weld bead geometry was found to be positively affected by the pulse width. Microstructural studies revealed the presence of dendritic and fine grain structures within the weld zone at low peak power, while ferritic microstructures were found on the sides of the weld metal near the SS 304 and austenitic-ferritic microstructure beside the duplex 2205 boundary. Regarding the micro-hardness tests, there was an improvement when compared to the hardness of duplex and austenitic stainless steels base metals. Additionally, the tensile strength of the fiber laser welded joints was found to be higher when compared to the tensile strength of the base metals (duplex and austenitic) in all of the joints. Full article

(This article belongs to the Special Issue Laser Welding)

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10746 KiB

Open AccessFeature PaperArticle

Laser Welding of BTi-6431S High Temperature Titanium Alloy

by Zhi Zeng, J. P. Oliveira, Xianzheng Bu, Mao Yang, Ruoxi Li and Zhimin Wang

Metals 2017, 7(11), 504; https://doi.org/10.3390/met7110504 - 15 Nov 2017

Cited by 8 | Viewed by 5187

Abstract

A new type of high temperature titanium alloy, BTi-6431S, has recently become the focus of attention as a potential material for aircraft engine applications, which could be used up to 700 °C. Pulsed laser welding was used to butt join the BTi-6431S titanium [...] Read more.

A new type of high temperature titanium alloy, BTi-6431S, has recently become the focus of attention as a potential material for aircraft engine applications, which could be used up to 700 °C. Pulsed laser welding was used to butt join the BTi-6431S titanium alloy in order to understand the feasibility of using fusion-based welding techniques on this material. The effect of laser energy on the microstructure and mechanical properties of the joints was investigated. The microstructural features of the joints were characterized by means of microscopy and X-ray diffraction. Tensile testing was conducted at both room temperature and high temperature to simulate potential service conditions. The results show that the microstructure of the laser welded joints consists of primary α phase and needle α’ phase, while the microstructure of the heat affected zone consists of α, β, and needle α’ phases. The tensile strength of the welded joints at room temperature was similar to that of the base material, despite a reduction in the maximum elongation was observed. This was related to the unfavorable microstructure in the welded joints. Nonetheless, based on these results, it is suggested that laser welding is a promising joining technique for the new BTi-6431S titanium alloy for aerospace applications. Full article

(This article belongs to the Special Issue Laser Welding)

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20713 KiB

Open AccessArticle

Microstructures and Mechanical Properties of Dissimilar Al/Steel Butt Joints Produced by Autogenous Laser Keyhole Welding

by Li Cui, Boxu Chen, Wei Qian, Dingyong He and Li Chen

Metals 2017, 7(11), 492; https://doi.org/10.3390/met7110492 - 10 Nov 2017

Cited by 28 | Viewed by 6508

Abstract

Dissimilar Al/steel butt joints of 6.0 mm thick plates have been achieved using fiber laser keyhole welding autogenously. The cross sections, interface microstructures, hardness and tensile properties of Al/steel butt joints obtained under different travel speeds and laser beam offsets were investigated. The [...] Read more.

Dissimilar Al/steel butt joints of 6.0 mm thick plates have been achieved using fiber laser keyhole welding autogenously. The cross sections, interface microstructures, hardness and tensile properties of Al/steel butt joints obtained under different travel speeds and laser beam offsets were investigated. The phase morphology and thickness of the intermetallic compound (IMC) layers at the interface were analyzed by scanning electronic microscopes (SEM) using the energy-dispersive spectrometry (EDS) and electron back-scattered diffraction (EBSD) techniques. The results show that travel speeds and laser beam offsets are of considerable importance for the weld shape, morphology and thickness of IMC layers, and ultimate tensile strength (UTS) of Al/steel butt joints. This proves that the IMC layers consist of Fe₂Al₅ phases and Fe₄Al₁₃ phases by EBSD phase mapping. Increasing laser beam offsets from 0.3 mm to 0.7 mm significantly decreases the quantity of Fe₄Al₁₃ phases and the thickness of Fe₂Al₅ layers at the interface. During tensile processing, the Fe₂Al₅ layer with the weakest bonding strength is the most brittle region at the interface. However, an intergranular fracture that occurred at Fe₂Al₅ layers leads to a relatively high UTS of Al/steel butt joints. Full article

(This article belongs to the Special Issue Laser Welding)

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17172 KiB

Open AccessArticle

Experimental Investigation on Electric Current-Aided Laser Stake Welding of Aluminum Alloy T-Joints

by Xinge Zhang, Liqun Li, Yanbin Chen, Zhaojun Yang and Xiaocui Zhu

Metals 2017, 7(11), 467; https://doi.org/10.3390/met7110467 - 1 Nov 2017

Cited by 8 | Viewed by 5330

Abstract

In the present study, aluminum alloy T-joints were welded using the laser stake-welding process. In order to improve the welding quality of the T-joints, an external electric current was used to aid the laser stake-welding process. The effects of the process parameters on [...] Read more.

In the present study, aluminum alloy T-joints were welded using the laser stake-welding process. In order to improve the welding quality of the T-joints, an external electric current was used to aid the laser stake-welding process. The effects of the process parameters on the weld morphology, mechanical properties, and microstructure of the welded joints were analyzed and discussed in detail. The results indicate that the aided electric current should be no greater than a certain maximum value. Upon increasing the aided electric current, the weld width at the skin and stringer faying surface obviously increased, but there was an insignificant change in the penetration depth. Furthermore, the electric current and pressing force should be chosen to produce an expected weld width at the faying surface, whereas the laser power and welding speed should be primarily considered to obtain an optimal penetration depth. The tensile shear specimens failed across the faying surface or failed in the weld zone of the skin. The specimens that failed in the weld of the skin could resist a higher tensile shear load compared with specimens that failed across the faying surface. The microstructural observations and microhardness results demonstrated that the tensile shear load capacity of the aluminum alloy welded T-joint was mainly determined by the weld width at the faying surface. Full article

(This article belongs to the Special Issue Laser Welding)

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17384 KiB

Open AccessArticle

Control of Porosity and Spatter in Laser Welding of Thick AlMg5 Parts Using High-Speed Imaging and Optical Microscopy

by Andrei C. Popescu, Christophe Delval and Marc Leparoux

Metals 2017, 7(11), 452; https://doi.org/10.3390/met7110452 - 26 Oct 2017

Cited by 18 | Viewed by 8751

Abstract

We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this [...] Read more.

We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this otherwise difficult-to-weld alloy. High-speed imaging of the welding process via an optical microscope allowed for recording at millimeter level, providing new information on liquid-metal dynamics during laser irradiation as well as plausible explanations for spatter occurrence and pores formation. The pore formation and especially the position of these pores had to be controlled in order to weld 3 mm thick samples. By tuning both laser power and pulse duration, pores were aligned on a single line, at the bottom of the weld. A laser pass of reduced power on that side was then sufficient for removing all pores and providing a suitable weld. Full article

(This article belongs to the Special Issue Laser Welding)

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12594 KiB

Open AccessArticle

FEM Simulation of Dissimilar Aluminum Titanium Fiber Laser Welding Using 2D and 3D Gaussian Heat Sources

by Sonia D’Ostuni, Paola Leo and Giuseppe Casalino

Metals 2017, 7(8), 307; https://doi.org/10.3390/met7080307 - 10 Aug 2017

Cited by 45 | Viewed by 8994

Abstract

For a dissimilar laser weld, the model of the heat source is a paramount boundary condition for the prediction of the thermal phenomena, which occur during the welding cycle. In this paper, both two-dimensional (2D) and three-dimensional (3D) Gaussian heat sources were studied [...] Read more.

For a dissimilar laser weld, the model of the heat source is a paramount boundary condition for the prediction of the thermal phenomena, which occur during the welding cycle. In this paper, both two-dimensional (2D) and three-dimensional (3D) Gaussian heat sources were studied for the thermal analysis of the fiber laser welding of titanium and aluminum dissimilar butt joint. The models were calibrated comparing the fusion zone of the experiment with that of the numerical model. The actual temperature during the welding cycle was registered by a thermocouple and used for validation of the numerical model. When it came to calculate the fusion zone dimensions in the transversal section, the 2D heat source showed more accurate results. The 3D heat source provided better results for the simulated weld pool and cooling rate. Full article

(This article belongs to the Special Issue Laser Welding)

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11022 KiB

Open AccessArticle

Effects of Pulsed Nd:YAG Laser Welding Parameters on Penetration and Microstructure Characterization of a DP1000 Steel Butt Joint

by Xin Xue, António B. Pereira, José Amorim and Juan Liao

Metals 2017, 7(8), 292; https://doi.org/10.3390/met7080292 - 1 Aug 2017

Cited by 40 | Viewed by 8161

Abstract

Of particular importance and interest are the effects of pulsed Nd:YAG laser beam welding parameters on penetration and microstructure characterization of DP1000 butt joint, which is widely used in the automotive industry nowadays. Some key experimental technologies including pre-welding sample preparation and optimization [...] Read more.

Of particular importance and interest are the effects of pulsed Nd:YAG laser beam welding parameters on penetration and microstructure characterization of DP1000 butt joint, which is widely used in the automotive industry nowadays. Some key experimental technologies including pre-welding sample preparation and optimization design of sample fixture for a sufficient shielding gas flow are performed to ensure consistent and stable testing. The weld quality can be influenced by several process factors, such as laser beam power, pulse duration, overlap, spot diameter, pulse type, and welding velocity. The results indicate that these key process parameters have a significant effect on the weld penetration. Meanwhile, the fusion zone of butt joints exhibits obviously greater hardness than the base metal and heat affected zone of butt joints. Additionally, the volume fraction of martensite of dual-phase steel plays a considerable effect on the hardness and the change of microstructure characterization of the weld joint. Full article

(This article belongs to the Special Issue Laser Welding)

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11473 KiB

Open AccessFeature PaperArticle

Effects of Laser Offset and Hybrid Welding on Microstructure and IMC in Fe–Al Dissimilar Welding

by Giuseppe Casalino, Paola Leo, Michelangelo Mortello, Patrizia Perulli and Alessandra Varone

Metals 2017, 7(8), 282; https://doi.org/10.3390/met7080282 - 25 Jul 2017

Cited by 39 | Viewed by 7114

Abstract

Welding between Fe and Al alloys is difficult because of a significant difference in thermal properties and poor mutual solid-state solubility. This affects the weld microstructure and causes the formation of brittle intermetallic compounds (IMCs). The present study aims to explore the weld [...] Read more.

Welding between Fe and Al alloys is difficult because of a significant difference in thermal properties and poor mutual solid-state solubility. This affects the weld microstructure and causes the formation of brittle intermetallic compounds (IMCs). The present study aims to explore the weld microstructure and those compounds over two different technologies: the laser offset welding and the hybrid laser-MIG (Metal inert gas) welding. The former consists of focusing the laser beam on the top surface of one of the two plates at a certain distance (offset) from the interfaces. Such a method minimizes the interaction between elevated temperature liquid phases. The latter combines the laser with a MIG/MAG arc, which helps in bridging the gap and stabilizing the weld pool. AISI 316 stainless steel and AA5754 aluminum alloy were welded together in butt configuration. The microstructure was characterized and the microhardness was measured. The energy dispersive spectroscopy/X-ray Diffraction (EDS/XRD) analysis revealed the composition of the intermetallic compounds. Laser offset welding significantly reduced the content of cracks and promoted a narrower intermetallic layer. Full article

(This article belongs to the Special Issue Laser Welding)

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11583 KiB

Open AccessFeature PaperArticle

Microstructure and Mechanical Properties of Ti5553 Butt Welds Performed by LBW under Conduction Regime

by Jose Maria Sánchez-Amaya, Timotius Pasang, Margarita Raquel Amaya-Vazquez, Juan De Dios Lopez-Castro, Cristina Churiaque, Yuan Tao and Francisco Javier Botana Pedemonte

Metals 2017, 7(7), 269; https://doi.org/10.3390/met7070269 - 13 Jul 2017

Cited by 15 | Viewed by 8204

Abstract

Ti-5Al-5V-5Mo-3Cr (Ti5553) is a metastable β titanium alloy with a high potential use in the aeronautic industry due to its high strength, excellent hardenability, fracture toughness and high fatigue resistance. However, recent research shows this alloy has a limited weldability. Different welding technologies [...] Read more.

Ti-5Al-5V-5Mo-3Cr (Ti5553) is a metastable β titanium alloy with a high potential use in the aeronautic industry due to its high strength, excellent hardenability, fracture toughness and high fatigue resistance. However, recent research shows this alloy has a limited weldability. Different welding technologies have been applied in the literature to weld this alloy, such as electron beam welding (EBW), gas tungsten arc welding (GTAW) or laser beam welding (LBW) under keyhole regime. Thus, in tensile tests, joints normally break at the weld zones, the strength of the welds being always lower than that of the base metal. In the present work, a novel approach, based on the application of LBW under conduction regime (with a High-Power Diode Laser, HPDL), has been employed for the first time to weld this alloy. Microstructure, microhardness and strength of obtained welds were analyzed and reported in this paper. LBW under conduction regime (LBW-CR) leads to welds with slightly higher values of Ultimate Tensile Strength (UTS) than those previously obtained with other joining processes, probably due to the higher hardness of the fusion zone and to lower porosity of the weld. Full article

(This article belongs to the Special Issue Laser Welding)

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9329 KiB

Open AccessArticle

The Influence of Laser Welding on the Mechanical Properties of Dual Phase and Trip Steels

by Emil Evin and Miroslav Tomáš

Metals 2017, 7(7), 239; https://doi.org/10.3390/met7070239 - 29 Jun 2017

Cited by 34 | Viewed by 6206

Abstract

Nowadays, a wide range of materials is used for car body structures in order to improve both the passengers’ safety and fuel consumption. These are joined by laser welding and solid state fiber lasers being used more and more in present. The article [...] Read more.

Nowadays, a wide range of materials is used for car body structures in order to improve both the passengers’ safety and fuel consumption. These are joined by laser welding and solid state fiber lasers being used more and more in present. The article is focused on the research of laser welding influence on the mechanical and deformation properties, microstructure and microhardness of advanced high-strength steels: high-strength low-alloyed steel HC340LA, dual phase steel HCT600X and multi-phase residual austenite steel RAK40/70. The proper welding parameters have been found based on weld quality evaluation. The specimens for tensile test with longitudinal laser weld were used to measure mechanical and deformation properties. Microstructure and microhardness of laser welds were evaluated in the base metal, heat affected zone and fusion zone. The higher values of strength and lower ones for deformation properties of laser-welded materials have been found for dual and multi-phase steel. The microhardness strongly depends on the carbon equivalent of steel. Deformation properties are more sensitive than strength properties to the change of microstructure in the fusion zone and heat affected zone. Full article

(This article belongs to the Special Issue Laser Welding)

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5018 KiB

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Multiphysics Simulation and Experimental Investigation of Aluminum Wettability on a Titanium Substrate for Laser Welding-Brazing Process

by Morgan Dal and Patrice Peyre

Metals 2017, 7(6), 218; https://doi.org/10.3390/met7060218 - 13 Jun 2017

Cited by 9 | Viewed by 5192

Abstract

The control of metal wettability is a key-factor in the field of brazing or welding-brazing. The present paper deals with the numerical simulation of the whole phenomena occurring during the assembly of dissimilar alloys. The study is realized in the frame of potential [...] Read more.

The control of metal wettability is a key-factor in the field of brazing or welding-brazing. The present paper deals with the numerical simulation of the whole phenomena occurring during the assembly of dissimilar alloys. The study is realized in the frame of potential applications for the aircraft industry, considering the case of the welding-brazing of aluminum Al5754 and quasi-pure titanium Ti40. The assembly configuration, presented here, is a simplification of the real experiment. We have reduced the three-dimensional overlap configuration to a bi-dimensional case. In the present case, an aluminum cylinder is fused onto a titanium substrate. The main physical phenomena which are considered here are: the heat transfers, the fluid flows with free boundaries and the mass transfer in terms of chemical species diffusion. The numerical problem is implemented with the commercial software Comsol Multiphysics™, by coupling heat equation, Navier-Stokes and continuity equations and the free boundary motion. The latter is treated with the Arbitrary Lagrangian Eulerian method, with a particular focus on the contact angle implementation. The comparison between numerical and experimental results shows a very satisfactory agreement in terms of droplet shape, thermal field and intermetallic layer thickness. The model validates our numerical approach. Full article

(This article belongs to the Special Issue Laser Welding)

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7366 KiB

Open AccessArticle

Laser Beam Welding of a Ti–6Al–4V Support Flange for Buy-to-Fly Reduction

by Fabrizia Caiazzo, Vittorio Alfieri, Gaetano Corrado, Paolo Argenio, Giuseppe Barbieri, Francesco Acerra and Vincenzo Innaro

Metals 2017, 7(5), 183; https://doi.org/10.3390/met7050183 - 20 May 2017

Cited by 13 | Viewed by 6228

Abstract

Titanium and its alloys are increasingly being used in aerospace, although a number of issues must be addressed. Namely, in the framework of welding to produce complex parts, the same mechanical strength and a reduced buy-to-fly ratio are desired in comparison with the [...] Read more.

Titanium and its alloys are increasingly being used in aerospace, although a number of issues must be addressed. Namely, in the framework of welding to produce complex parts, the same mechanical strength and a reduced buy-to-fly ratio are desired in comparison with the same components resulting from machining. To give grounds to actual application of autogenous laser beam welding, Ti–6Al–4V L- and T-joints have been investigated in this paper, as they are a common occurrence in general complex components. Discussions in terms of possible imperfections, microstructure, and microhardness have been conducted. Then, a real part consisting of a support flange for aerospace application has been chosen as a valuable test-article to be compared with its machined counterpart both in terms of strength and buy-to-fly. The feasibility and the effectiveness of the process are shown. Full article

(This article belongs to the Special Issue Laser Welding)

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