scholarly journals Investigation into the Effect of RFSSW Parameters on Tensile Shear Fracture Load of 7075-T6 Alclad Aluminium Alloy Joints

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3397
Author(s):  
Andrzej Kubit ◽  
Tomasz Trzepieciński ◽  
Elżbieta Gadalińska ◽  
Ján Slota ◽  
Wojciech Bochnowski
Keyword(s):  
Aluminium Alloy ◽  
Shear Fracture ◽  
Load Capacity ◽  
Fracture Load ◽  
Tensile Fracture ◽  
Welding Parameters ◽  
Tensile Shear ◽  
Optimal Amount ◽  
Average Value ◽  
Type Fracture

The aim of the investigations was to determine the effect of parameters of refill friction stir spot welding (RFSSW) on the fracture load and failure mechanisms of the resulting joint. RFSSW joints were made in 7075-T6 Alclad aluminium alloy sheets using different welding parameters. The load capacity of joints was determined under tensile/shear loadings. Finite element-based numerical simulations of the joint-loading process were carried out, taking into account the variability of elasto-plastic properties of weld material through the joint cross-section. The influence of welding parameters on selected phenomena occurring during the destruction of the joint is presented. The considerations were supported by a fractographic analysis based on SEM images of fractures. It was found that there is a certain optimal amount of heat generated, which is necessary to produce the correct joint in terms of its load capacity. This value should not be exceeded, because it leads to weakening of the base material and thus to a reduction in the strength of the joint. Samples subjected to uniaxial tensile shear load showed three types of failure mode (tensile fracture, shear fracture, plug type fracture) depending on the tool rotational speed and duration of welding. Prediction of the fracture mode using FE-based numerical modelling was consistent with the experimental results. The samples that were damaged due to the tensile fracture of the lower sheet revealed a load capacity (LC) of 5.76 KN. The average value of LC for the shear fracture failure mechanism was 5.24 kN. The average value of the LC for plug-type fracture mode was 5.02 kN. It was found that there is an optimal amount of heat generated, which is necessary to produce the correct joint in terms of its LC. Excessive overheating of the joint leads to a weakening of the base metal and thus a reduction in the strength of the joint. Measurements of residual stresses along the axis specimens showed the presence of stresses with a certain constant value for the welded area on the side of the 1.6 mm thick plate.

Influence of resistance spot welding process parameters on dissimilar austenitic and duplex stainless steel welded joints

2020 ◽  
pp. 095440892093352
Author(s):  
Vignesh Krishnan ◽  
Elayaperumal Ayyasamy ◽  
Velmurugan Paramasivam
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Shear Fracture ◽  
Welding Current ◽  
Fracture Load ◽  
Welding Parameters ◽  
Shear Load ◽  
Tensile Shear ◽  
Aisi 316 ◽  
Aisi 316 L

This paper examines the impact of welding parameters on tensile shear fracture load, nugget geometry and microstructure of resistance spot welds (RSW) of austenitic stainless steel AISI 316 L and duplex stainless steel 2205 under lap shear loading condition. The macroscopic examination resulted that many of the nugget lengths were nearer to and higher than the AWS recommended value 4√t and failed at higher tensile shear load. Nugget height for DSS 2205 side was higher in comparison with AISI 316 L due to higher thermal conductivity of duplex stainless steel. Three welding parameters mainly welding current of 9 kA, heating cycle of 9 and electrode tip diameter of 6 mm were discovered as most effectual parameters on the tensile shear load and microstructure of weldments. Heterogeneous hardness was observed in the fusion zone due to the transition of equiaxed to columnar grains takes place in the both sides of nugget edge. DSS HAZ nearby BM observed higher hardness and ASS HAZ nearby BM reported lower hardness. WMZ Microstructure confirmed that thickness of austenite layers increased with heat input. Also, an unmixed zone in the microstructure identified as HAZ which contains delta ferrite. Scanning Electron Microscope (SEM) images in the nugget zone for different welding parameters confirmed that Intra-Granular Austenite (IGA) highly developed at higher welding current. SEM fractrograph for the tensile sheared specimens at higher and lower heat input confirmed the ductile type fracture even failed at Inter-Facial (IF) mode. Nugget area and nugget hardness were positively correlated with Tensile Shear Fracture Load (TSFL).

scholarly journals Effect of Microstructure and Texture on Mechanical Properties of Resistance Spot Welded High Strength Steel 22MnB5 and 5A06 Aluminium Alloy

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 685
Author(s):  
Xiaoqing Jiang ◽  
Shujun Chen ◽  
Jinlong Gong ◽  
Zhenyang Lu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Aluminium Alloy ◽  
High Strength Steel ◽  
High Strength ◽  
Welding Parameters ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Resistance Spot ◽  
Effect Of Microstructure

The present study aims to investigate the effect of microstructure and texture on mechanical properties of resistance spot welding of high strength steel 22MnB5 and 5A06 aluminium alloy as a function of welding parameters. The pseudo-nugget zones (NZs) at the steel side have undergone full recrystallisation with a fine-grained ferrite structure containing a small amount of retained austenite and a high hardness of approximately 500 HV, which is a 35% increase in hardness compared to the base material (BM) with fine lath martensitic structure. The NZs at the Al side contain both a recrystallisation texture and shear texture. Higher tensile shear strength with increasing weld time could be linked to the random texture at the Al side. The highest tensile shear strength was achieved at an intermetallic layer thickness of 4 mm.

scholarly journals Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 286 ◽  
Author(s):  
Lipeng Deng ◽  
Shuhan Li ◽  
Liming Ke ◽  
Jinhe Liu ◽  
Jidong Kang
Keyword(s):  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Load Capacity ◽  
Maximum Load ◽  
Fusion Welding ◽  
Tensile Shear ◽  
Friction Stir ◽  
Corona Ring ◽  
Spot Welded

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

AN EMPIRICAL RELATIONSHIP FOR ESTIMATING METALLURGICAL AND MECHANICAL BEHAVIOR OF RESISTANCE SPOT WELDED DP800 STEEL JOINTS

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Rajarajan C ◽  
Sivaraj P ◽  
Balasubramanian V
Keyword(s):  
Shear Fracture ◽  
Empirical Relationship ◽  
Testing Machine ◽  
Welding Current ◽  
Fracture Load ◽  
Peak Hardness ◽  
Tensile Shear ◽  
Nugget Zone ◽  
Resistance Spot ◽  
Increase With Increase

Similar joints of DP800 (Dual Phase) steel in lap joint configuration were fabricated using resistance spot welding (RSW) process. The process parameters were optimized using DOE (design of experiments) and the welds joints were fabricated using the obtained DOE matrix. The tensile shear fracture load (TSFL) of joints was evaluated using universal testing machine. Microhardness variations across the weld cross-section was recorded using Vickers’s microhardness tester. Microstructural features were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). From this investigation, it is understood that increase in welding current increases the nugget zone size and it led to increasing the degrease of softening in the HAZ. The tensile shear strength is found to increase with increase in welding current up to a certain limit and then it decreases. The microhardness profile shows a peak hardness in nugget zone and the hardness is lower in the HAZ. The softening of HAZ is mainly attributed to inter-critical heating during welding.

scholarly journals Spot Welding of 6061 Aluminum Alloy by Friction Stir Spot Welding Process

2017 ◽  
Vol 7 (3) ◽  
pp. 1629-1632 ◽  
Author(s):  
M. A. Tashkandi ◽  
J. A. Al-jarrah ◽  
M. Ibrahim
Keyword(s):  
Welded Joints ◽  
Spot Welding ◽  
Shear Fracture ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Fracture Load ◽  
Welding Parameters ◽  
Friction Stir ◽  
Pull Out ◽  
Lap Shear

This study was focused on the effect of welding parameters on the lap-shear fracture load of the welded joints prepared by friction stir spot welding. Four different weld parameters were analyzed: rotational speed, dwell time, pin length and shoulder size of the welding tool. It was found that the lap-shear fracture load increases with an increase of the welding parameters to a limited value and decreases with further increase. The strong welded joints failed under nugget-pull out fracture.

Taguchi Optimization of Process Parameters in Friction Stir Spot Welding of AA5754 and AA2024 Alloys

2014 ◽  
Vol 1016 ◽  
pp. 161-166 ◽  
Author(s):  
Y. Bozkurt ◽  
Mustafa Kemal Bilici
Keyword(s):  
Spot Welding ◽  
Shear Fracture ◽  
Signal To Noise Ratio ◽  
Statistical Design ◽  
Friction Stir Spot Welding ◽  
Fracture Load ◽  
Welding Parameters ◽  
Taguchi Optimization ◽  
Friction Stir ◽  
Lap Shear

The feasibility of friction stir spot welding was studied on AA5754-H22 and AA2024-T3 aluminum alloys which have widespread applications in aircraft and automotive industries. The quality of the joint was evaluated by examining the characteristics of the joint as a result of lap-shear fracture load. Taguchi approach of the parameter design was used as a statistical design of experiment technique to set the optimal welding parameters. The experiments were arranged by using Taguchi’s L9 orthogonal array. The signal-to-noise ratio and the analysis of variance were utilized to obtain the influence of the friction stir spot welding parameters on the lap-shear fracture load. Finally, the results were confirmed by further experiments.

Effect of Coating Layer on Advanced Stud Welding of 2024 Aluminum Alloy to Galvanized and Galvannealed Steel Sheet

2014 ◽  
Vol 794-796 ◽  
pp. 351-356
Author(s):  
Yohei Harada ◽  
Kozo Ishizuka ◽  
Shinji Kumai
Keyword(s):  
Aluminum Alloy ◽  
Steel Sheet ◽  
Coating Layer ◽  
Fracture Load ◽  
Tensile Fracture ◽  
2024 Aluminum Alloy ◽  
Steel Sheets ◽  
Sheet Surface ◽  
Stud Welding ◽  
Galvannealed Steel

High strength 2024 aluminum alloy studs were joined to galvanized, galvannealed and non-coated steel sheets by using an advanced stud welding method. Effect of the coating layer on the interfacial microstructure and the tensile fracture load of the joints were evaluated. A specially-designed stud having a circular projection at its bottom was pressed against a sheet surface. A discharge current was introduced from the upper part of the stud. Local heating could be achieved by a high current density at a contact point between the projection and sheet. The observation of joint area revealed the projection was severely deformed and spread along the sheet surface. The coating layer of the galvanized steel sheet was removed at the joint interface under the charging voltage of 200 V, while that of the galvannealed one locally remained on the steel surface even at 400 V. This would be strongly related to the melting or liquidus and solidus temperatures of each coating layer. Joining was not achieved at a low charging voltage in the non-coated and galvannealed steel sheets, while high tensile fracture load was obtained even at 200 V in the galvanized ones.

Experimental analysis of the automated process of sanding aircraft surfaces

2014 ◽  
Vol 118 (1199) ◽  
pp. 53-64
Author(s):  
B. Giublin ◽  
J. A. Vieira ◽  
T. G. Vieira ◽  
L. G. Trabasso ◽  
C. A. Martins
Keyword(s):  
Load Capacity ◽  
Manufacturing Processes ◽  
Robotic Cell ◽  
Research Project ◽  
Average Value ◽  
Aluminum Metal ◽  
Structural Assembly ◽  
Riveting Process ◽  
High Load Capacity ◽  
Operating Method

Abstract ITA and EMBRAER are currently executing the research project Automation of Aircraft Structural Assembly (AASA) whose goal is to implement a robotic cell for automating the riveting process of aeronautical structures. The proposal described herein complements the AASA project, adds other manufacturing processes, namely sanding and polishing of aircraft surfaces. To implement the additional processes AASA project resources and facilities were used (robots and metrology systems) and devices designed and /or acquired to allow sharing of these resources. Among these, an Automatic Tooling Support for AERonautics structures (ATS_AER) was designed and built; also, a robot tool changer with high load capacity was acquired. The outcome of this research project is the evaluation of the feasibility of automating the processes of sanding and polishing metal surfaces in the aircraft manufacture using robots. The operating method adopted for surface treatment employed the ‘U’ type trajectory optimised to be run by a KUKA robot KR 500. The sanding process has been applied to aluminum metal sheet specimen sized 2•18ft2 (0•20m2) and used commercial 600 and 800 sandpaper. The automated sanding process yielded an average value of RA 0•48 ± 0•08 which is 25% more efficient when compared to the traditional, manual process whose average value of RA is 0•75 ± 0•51.

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