scholarly journals Metallographic evaluation of the weldability of high strength aluminium alloys using friction spot welding

2017 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Jeroen Vercauteren ◽  
Koen Faes ◽  
Wim De Waele
Keyword(s):  
Aluminium Alloys ◽  
Spot Welding ◽  
High Strength ◽  
Frictional Heat ◽  
Friction Spot Welding ◽  
Lap Shear ◽  
Spot Joining ◽  
Published Research ◽  
Interface Imperfections ◽  
Welding Technique

Friction spot welding is a recent solid-state welding technique well suited for spot-joining lightweight materials in overlap condition. Aerospace and transport industries show great interest in this technique to join high-strength aluminium alloys, but published research is still limited. In this project, the link between process parameters and weld quality is investigated for EN AW-7075-T6 material. Techniques used are metallographic qualification, measurement of hardness reduction and lap shear strength. This paper focusses on the metallographic investigation of the weld region and its imperfections. Increasing joining time and heat input creates an easier material flow resulting in fewer imperfections. Limited plunge depths lead to typical interface imperfections. Variation in the rotational speed shows distinctive stir zone shapes as a consequence of severe stirring and frictional heat.

Preliminary Investigation on Friction Spot Welding of AZ31 Magnesium Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 3016-3021 ◽  
Author(s):  
L.C. Campanelli ◽  
U.F.H. Suhuddin ◽  
Jorge Fernandez Dos Santos ◽  
N.G. Alcantara
Keyword(s):  
Magnesium Alloy ◽  
Spot Welding ◽  
Welding Process ◽  
High Energy ◽  
Az31 Magnesium Alloy ◽  
Frictional Heat ◽  
Welding Parameters ◽  
Friction Stir ◽  
Friction Spot Welding ◽  
Lap Shear

Friction spot welding (FSpW) is a recent solid state welding process developed and patented by GKSS Forschungszentrum (now Helmholtz-Zentrum Geesthacht), Germany. A spot-like connection is produced by means of an especially designed non-consumable tool consisting of pin, sleeve and clamping ring that creates a joint between sheets in overlap configuration through frictional heat and plastic deformation. FSpW offers many advantages over conventional spot joining techniques including high energy efficiency, surface quality and environmental compatibility. Comparing with friction stir spot welding, FSpW produces a weld without keyhole on the surface at the end of the joining process. In the present study, the possibility of joining AZ31 magnesium alloy by FSpW technique was evaluated by using different welding parameters (rotational speed, plunge depth and dwell time), aiming to produce high quality connections. Microstructural features were analyzed by light optical microscope and mechanical performance was investigated by microhardness test and lap shear test. Microstructure analysis revealed that defects free welds could be produced. A slight decrease in grain size of the stir zone was observed causing a slight increase in the microhardness of this region. The preliminary lap shear data demonstrated that the weld strength is comparable to other welding process.

scholarly journals Experimental investigation of the weldability of high strength aluminium using friction spot welding

2016 ◽  
Vol 7 (1) ◽  
pp. 8 ◽  
Author(s):  
T. Kolba ◽  
Koen Faes ◽  
Wim De Waele
Keyword(s):  
Spot Welding ◽  
Mechanical Performance ◽  
Rotation Speed ◽  
High Strength ◽  
Industrial Applications ◽  
Frictional Heat ◽  
Friction Spot Welding ◽  
Depth Rotation ◽  
Static Tensile ◽  
Specific Material

Friction spot welding is a technique for joining lightweight aluminium and magnesium alloys in the overlap configuration by means of frictional heat and mechanical work and has a high potential for industrial applications. As this is a very recent technique, little information is available regarding the evaluation and optimisation of process parameters for specific material combinations. The process has been used to investigate the weldability of the high strength aluminium alloy EN AW-7475-T761, aiming to produce high quality joints in terms of mechanical performance and microstructure. More specific, the influence of the plunge depth, rotation speed and welding time was investigated. The paper first shortly describes the process and continues with the results of the microhardness, static tensile and optical microscopy tests.

scholarly journals Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

2021 ◽  
Author(s):  
Andrew Macwan
Keyword(s):  
Diffusion Layer ◽  
Spot Welding ◽  
Frictional Heating ◽  
Hsla Steel ◽  
Weight Ratio ◽  
High Strength ◽  
Phase Identification ◽  
Welding Time ◽  
Interface Diffusion ◽  
Lap Shear

Lightweighting has been regarded as a key strategy in the automotive industry to improve fuel efficiency and reduce anthropogenic environment-damaging, climate-changing, and costly emissions. Magnesium (Mg) alloys and Aluminum (Al) alloys are progressively more used in the transportation industries to reduce the weight of vehicles due to their high strength-to-weight ratio. Similarly, high strength low alloy (HSLA) steel is widely used to reduce gauge thickness and still maintain the same strength, and thereby reduce vehicle weight as well. A multi-material design of automotive structures and parts inevitably involve similar Mg-to-Mg and dissimilar Mg-to-Al, Al-to-steel, and Mg-to-Cu joints. Ultrasonic spot welding (USW) – a solid-state joining technique has recently received significant attention due to its higher efficiency in comparison with conventional fusion welding techniques. In this study, USW was used to generate similar joints of low rare-earth containing ZEK100 Mg alloy sheets and dissimilar ZEK100-to-Al5754, Al6111-to-HSLA steel, and Mg-to-Cu joints at different levels of welding energy or welding time. To optimize welding process and identify key factors affecting the weld strength, microstructural evolution, microhardness test, tensile lap shear test, fatigue test, and fracture analysis were performed on similar and dissimilar ultrasonic spot welded (USWed) joints. Dynamic recrystallization and grain coarsening were observed during Mg-to-Mg similar welding while rapid formation and growth of interface diffusion layer were observed in all dissimilar joints in the present study. It was due to significantly high strain rate (~103 s-1) and high temperature generated via frictional heating during USW. The interface diffusion layer was analyzed by SEM, EDS and XRD phase identification techniques which showed the presence of eutectic structure containing intermetallic compounds (IMCs). As a result, brittleness at the interface increased. The Zn coating in dissimilar USWed Al-to-steel joints eliminated the formation of brittle IMCs of Al-F, which were replaced by relatively ductile AlZn eutectic. The optimum welding energy or welding time during similar and dissimilar USW of lightweight alloys with a sheet thickness of 1-2 mm was in the range of ~500 J to 2000 J (~0.25 s to 1 s).

scholarly journals Parameters optimization for friction spot welding of AZ31 magnesium alloy by Taguchi method

2012 ◽  
Vol 17 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Leonardo Contri Campanelli ◽  
Uceu Fuad Hasan Suhuddin ◽  
Jorge Fernandez dos Santos ◽  
Nelson Guedes de Alcântara
Keyword(s):  
Shear Strength ◽  
Magnesium Alloy ◽  
Rotational Speed ◽  
Spot Welding ◽  
Dwell Time ◽  
Az31 Magnesium Alloy ◽  
Lap Shear Strength ◽  
Plunge Depth ◽  
Friction Spot Welding ◽  
Lap Shear

Friction spot welding (FSpW) is a solid state welding process suitable for producing spot-like joints, especially in lightweight materials, which are particularly interesting due to the weight saving potential. The plunging of an especially designed non-consumable and rotating tool creates a connection between overlapped sheets through frictional heat and plastic deformation. Minimum material loss is observed, and therefore a fully consolidated joint with flat surface (no keyhole) is obtained. In the current study, the effect of FSpW parameters, such as rotational speed, plunge depth and dwell time, on lap shear strength of AZ31 magnesium alloy joints was investigated. The optimization of input process parameters was carried out through Taguchi approach of DOE. Analysis of variance was applied to determine the individual importance of each parameter. Main effect plots were used to indicate the best levels for maximizing lap shear strength. The results show that tool plunge depth has the higher effect on the weld strength, followed by rotational speed and dwell time.

Numerically modelled study of the plunge stage in friction stir spot welding using multi-tiered mesh partitions

2021 ◽  
Author(s):  
Arindom Baruah ◽  
Jayaprakash Murugesan ◽  
Hemant Borkar
Keyword(s):  
Spot Welding ◽  
Material Model ◽  
Friction Stir Spot Welding ◽  
Frictional Heat ◽  
Complex Behaviour ◽  
Friction Stir ◽  
Spot Joining ◽  
Solid State Joining ◽  
Joining Process ◽  
Significant Attention

Abstract Friction stir spot welding is a solid-state joining process that has attracted significant attention particularly in the field of joining of lightweight, low melting alloys. These materials include alloys of Aluminium and Magnesium amongst many others which are of great importance to the aerospace and the automobile industries. The friction stir spot welding is a complex thermo-mechanical multiphysics phenomenon and is currently a field of intense research. The motivation of the current study is to understand this complex behaviour of the joining process by simulating it in the ABAQUS CAE environment. In the friction stir spot joining technique, the plunge stage is identified as the critical stage of operation as it involves a highly transient and dynamic zone for material and temperature flows. The plunge stage was studied in detail using the finite element based model. The plasticity of the material was simulated by the Johnson-Cook material model while the frictional heat generation was captured by applying a penalty-based frictional contact between the rotating tool and the workpiece contact surfaces. Considering the reasonable assumptions made, the results obtained by the numerical simulation model were found to agree with the past experimental and numerically modelled studies.

scholarly journals Review on Multi-Pass Friction Stir Processing of Aluminium Alloys

2020 ◽  
Author(s):  
Oritonda Muribwathoho ◽  
Sipokazi Mabuwa ◽  
Velaphi Msomi
Keyword(s):  
Friction Stir Processing ◽  
Aluminium Alloys ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Properties ◽  
Dissimilar Metals ◽  
Friction Stir ◽  
Aluminium Copper ◽  
The Impact ◽  
Welding Technique

Aluminium alloys have evolved as suitable materials for automotive and aircraft industries due to their reduced weight, excellent fatigue properties, high-strength to weight ratio, high workability/formability, and corrosion resistance. Recently, the joining of similar and dissimilar metals have achieved huge success in various sectors. The processing of soft metals like aluminium, copper, iron and nickel have been fabricated using friction stir processing. Friction stir processing (FSP) is a microstructural modifying technique that uses the same principles as the friction stir welding technique. In the majority of studies on FSP, the effect of process parameters on the microstructure was characterized after a single pass. However, multiple passes of FSP is another method to further modify the microstructure in aluminium castings. This study is aimed at reviewing the impact of multi-pass friction stir processed joints of aluminium alloys and to identify a knowledge gap. From the literature that is available on multi-pass FSP, it has been observed that the majority of the literature focused on the processing of plates than the joints. There is limited literature reporting on multi-pass friction stir processed joints. This then creates a need to study further on multi-pass friction stir processing on dissimilar aluminium alloys.

Fracture Behavior of Friction Stir Spot Welded Joint

2010 ◽  
Author(s):  
Abdel-Hamid I. Mourad ◽  
Khalifa H. Harib ◽  
Aly El-Domiaty
Keyword(s):  
Penetration Depth ◽  
Spot Welding ◽  
Fracture Behavior ◽  
Fracture Behaviour ◽  
Frictional Heat ◽  
Experimental Program ◽  
Main Process ◽  
Tensile Shear ◽  
Friction Stir ◽  
Lap Shear

The fracture behaviour of lap-shear joints manufactured by friction stir spot welding (FSSW) technique is examined in this paper. Two aluminium sheets of 2.8 mm thickness were welded using different process parameters to form a lap-shear joint. Special tool was designed and fabricated for the stir-spot welding process. Tensile-shear tests were performed to determine the tensile-shear load bearing capacity and toughness of the weld. The stress intensity factor and the J-integral around a weld are determined in order to characterize the fracture behavior. The effect of different main process controlling parameters, e.g., the tool prop pin rotating speed, duration action time and sinking/penetration depth into the lower welded sheet on the weld fracture behaviour has been investigated through an intensive experimental program. Optical and scanning electron microscopes fractographes were obtained to examine the weld fracture modes. The results show that higher frictional heat due to relatively higher tool probe pin rotational speed and penetration depth into the lower sheet produces improved joint static strength and toughness.

Friction spot welding of dissimilar 6063/5083 aluminium alloys

2017 ◽  
Vol 33 (14) ◽  
pp. 1626-1634 ◽  
Author(s):  
Zhengwei Li ◽  
Zhiwu Xu ◽  
Liguo Zhang ◽  
Zhongjie Yan
Keyword(s):  
Aluminium Alloys ◽  
Spot Welding ◽  
Friction Spot Welding

scholarly journals Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

2021 ◽  
Author(s):  
Andrew Macwan
Keyword(s):  
Diffusion Layer ◽  
Spot Welding ◽  
Frictional Heating ◽  
Hsla Steel ◽  
Weight Ratio ◽  
High Strength ◽  
Phase Identification ◽  
Welding Time ◽  
Interface Diffusion ◽  
Lap Shear

Lightweighting has been regarded as a key strategy in the automotive industry to improve fuel efficiency and reduce anthropogenic environment-damaging, climate-changing, and costly emissions. Magnesium (Mg) alloys and Aluminum (Al) alloys are progressively more used in the transportation industries to reduce the weight of vehicles due to their high strength-to-weight ratio. Similarly, high strength low alloy (HSLA) steel is widely used to reduce gauge thickness and still maintain the same strength, and thereby reduce vehicle weight as well. A multi-material design of automotive structures and parts inevitably involve similar Mg-to-Mg and dissimilar Mg-to-Al, Al-to-steel, and Mg-to-Cu joints. Ultrasonic spot welding (USW) – a solid-state joining technique has recently received significant attention due to its higher efficiency in comparison with conventional fusion welding techniques. In this study, USW was used to generate similar joints of low rare-earth containing ZEK100 Mg alloy sheets and dissimilar ZEK100-to-Al5754, Al6111-to-HSLA steel, and Mg-to-Cu joints at different levels of welding energy or welding time. To optimize welding process and identify key factors affecting the weld strength, microstructural evolution, microhardness test, tensile lap shear test, fatigue test, and fracture analysis were performed on similar and dissimilar ultrasonic spot welded (USWed) joints. Dynamic recrystallization and grain coarsening were observed during Mg-to-Mg similar welding while rapid formation and growth of interface diffusion layer were observed in all dissimilar joints in the present study. It was due to significantly high strain rate (~103 s-1) and high temperature generated via frictional heating during USW. The interface diffusion layer was analyzed by SEM, EDS and XRD phase identification techniques which showed the presence of eutectic structure containing intermetallic compounds (IMCs). As a result, brittleness at the interface increased. The Zn coating in dissimilar USWed Al-to-steel joints eliminated the formation of brittle IMCs of Al-F, which were replaced by relatively ductile AlZn eutectic. The optimum welding energy or welding time during similar and dissimilar USW of lightweight alloys with a sheet thickness of 1-2 mm was in the range of ~500 J to 2000 J (~0.25 s to 1 s).

Microstructure of resistance spot welding of maraging steels

1990 ◽  
Vol 48 (4) ◽  
pp. 900-901
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff
Keyword(s):  
Maraging Steel ◽  
Spot Welding ◽  
Lath Martensite ◽  
Base Material ◽  
Aging Treatment ◽  
High Strength ◽  
Maraging Steels ◽  
Heat Treated ◽  
Current Cycle ◽  
Welding Processes

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.

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