Investigation of the effect of sheet thickness on residual stresses in resistance spot welding of aluminum sheets

2016 ◽  
Vol 232 (4) ◽  
pp. 621-638 ◽  
Author(s):  
M Sedighi ◽  
D Afshari ◽  
F Nazari
Keyword(s):  
Residual Stresses ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Sheet Thickness ◽  
Diffraction Method ◽  
Welding Current ◽  
Electrical Current ◽  
Element Model ◽  
Resistance Spot ◽  
Aluminum Sheets

The main purpose of this study is to investigate the effect of sheet thickness on nugget size and residual stresses in resistance spot welding. A two-dimensional coupled electro-thermo-mechanical finite element model is employed to predict the residual stresses in aluminum alloy 6061-T6. The simulation results are compared with the results obtained from the experimental nugget size and the residual stresses are measured by the X-ray diffraction method. The results indicate that the highest tensile residual stress occurs at the center of the nugget and diminish along the nugget radius. The residual stresses increase on increasing the electrical current and reducing the welding time. By increasing the sheet thickness, the affordable range of welding current and welding cycle increase. It also leads to the enlargement of the nugget, which consequently results in the increase of the residual stresses.

scholarly journals Optimization on Spot Weld Parameters in Resistance Spot Welding Process on AISI 304

2021 ◽  
Vol 11 (3) ◽  
pp. 181-185
Author(s):  
Amit Hazari ◽  
Rith Saha ◽  
Bidisha Ghosh ◽  
Debraj Sengupta ◽  
Sayan Sarkar ◽  
...  
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Welding Current ◽  
Electrical Current ◽  
Industrial Applications ◽  
Spot Weld ◽  
Welding Parameters ◽  
Resistance Spot ◽  
Weld Time

The spot welding procedure is used in a variety of industrial applications. The most critical elements influencing welding quality, productivity, and cost are the spot welding parameters. This research examines the effect of welding factors such as welding current and welding time on the strength of various welding joint designs. Resistance spot welding (RSW) is used in the automotive industry for manufacturing. This research focused on the optimization of process parameters for resistance spot welding (RSW), as well as the tensile testing and spot weld diameter. The goals of this analysis are to comprehend the physics of the process and to demonstrate the effect of electrical current, weld time, and material type on the resistance spot welding process.

Transport Phenomena During Resistance Spot Welding

1996 ◽  
Vol 118 (3) ◽  
pp. 762-773 ◽  
Author(s):  
P. S. Wei ◽  
S. C. Wang ◽  
M. S. Lin
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Transport Phenomena ◽  
Electrical Contact ◽  
Cone Angle ◽  
Welding Current ◽  
Electrical Current ◽  
Temperature Fields ◽  
Electrical Contact Resistance ◽  
Resistance Spot

Unsteady, axisymmetric transport of mass, momentum, energy, species, and magnetic field intensity with a mushy-zone phase change in workpieces and temperature, and magnetic fields in electrodes during resistance spot welding, are systematically investigated. Electromagnetic force, joule heat, heat generation at the electrode–workpiece interface and faying surface between workpieces, different properties between phases, and geometries of electrodes are taken into account. The computed results show consistencies with observed nugget growth, electrical current, and temperature fields. The effects of the face radius and cone angle of the electrode, parameters governing welding current, electrical contact resistance, magnetic Prandtl number, electrical conductivity ratio, and workpiece thickness on transport phenomena are clearly provided.

A Study on the Residual Stresses in Resistance Spot Welding

2015 ◽  
Vol 3 (2) ◽  
pp. 28-32
Author(s):  
Yasser Rihan ◽  
◽  
S. Ayyad ◽  
M.I. Elamy ◽  
◽  
...  
Keyword(s):  
Residual Stresses ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Resistance Spot

Micro Hardness in the Welded Area at Resistance Spot Welding

2016 ◽  
Vol 1138 ◽  
pp. 153-158
Author(s):  
Mihai Boca ◽  
Gheorghe Nagit ◽  
Laurenţiu Slătineanu
Keyword(s):  
Mechanical Properties ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Graphical Representation ◽  
Welding Process ◽  
Electrical Current ◽  
Micro Hardness ◽  
Current Time ◽  
Resistance Spot ◽  
Welding Spot

The resistance spot welding process represents the welding technology used to obtain assemblies trough welded spots characterized by adequate mechanical properties. This assembly process is used mainly into the automotive, petroleum and naval industries. It is applied due to the significant advantages concerning the technology and service properties of the obtained assembly. This paper purposes a study concerning the micro hardness change of an assembly made by resistance welding spot. The entire process of plastic deformations together with the solidification step developed in the presence of the heat generated during welding process determines the mechanical characteristics of the welded spot and, of course, of the assembly obtained. In such conditions, depending on the changes developed during the welding process, the micro hardness of the welded spot varies between the fusion area (FA) and heat affected zone (HAZ). In this way, the graphical representation of the micro hardness repartition gives clues about the weakness areas which don’t correspond to the requirements. As input factors, in this study, the values of current intensity, the electrical current time and the force pressure were considered. In order to solve the proposed problem and to graphically highlight the variation of the micro hardness obtained for welded points, it was used a classical welding device and a micro hardness device analyzer. The graphical representation shows that the micro-hardness and, as a consequence, some mechanical properties changes in the specified region and in the entire mass of the welded spot changes. In this way, the structure of welded spot is characterized by a variation of the hardness in the interest areas.

Simulations of Residual Stresses in Resistance Spot Welding Process

2010 ◽  
Vol 33 (9) ◽  
pp. 843-857 ◽  
Author(s):  
R. Dalewski ◽  
J. Jachimowicz ◽  
M. Pietrzakowski
Keyword(s):  
Residual Stresses ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Resistance Spot

Dynamic Electrode Force and Displacement in Resistance Spot Welding of Aluminum

2004 ◽  
Vol 126 (3) ◽  
pp. 605-610 ◽  
Author(s):  
C. T. Ji, ◽  
Y. Zhou,
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Current ◽  
Monitoring And Control ◽  
Resistance Spot ◽  
Nugget Diameter ◽  
Electrode Force ◽  
Rate Of Increase ◽  
Process Monitoring And Control ◽  
Electrode Displacement

Dynamic electrode displacement and force were characterized during resistance spot welding of aluminum alloy 5182 sheets using a medium-frequency direct-current welder. It was found that both electrode displacement and force increased rapidly at the beginning of the welding stage and then at a reducing rate. Rates of increase in electrode displacement and force were both proportional to welding current. And both electrode displacement and force experienced a sudden drop when weld metal expulsion occurred. However, the rate of increase in electrode displacement did not reach zero during welding even for joints with sufficient nugget diameter, while electrode force peaked when a large nugget diameter was produced. Possible strategies for process monitoring and control were also discussed.

Expulsion Intensity Monitoring and Modeling in Resistance Spot Welding Based on Electrode Displacement Signals

2020 ◽  
Author(s):  
Yu-Jun Xia ◽  
Yan Shen ◽  
Lang Zhou ◽  
Yong-Bing Li
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Low Carbon Steel ◽  
Sheet Thickness ◽  
High Strength Steels ◽  
High Strength ◽  
Material Strength ◽  
Low Carbon ◽  
Resistance Spot ◽  
Electrode Displacement

Abstract Weld expulsion is one of the most common welding defects during resistance spot welding (RSW) process especially for high strength steels (HSS). In order to control and eventually eliminate weld expulsion in production, accurate assessment of the expulsion severity should be the first step and is urgently required. Among the existing methods, real-time monitoring of RSW-related process signals has become a promising approach to actualize the online evaluation of weld expulsion. However, the inherent correlation between the process signals and the expulsion intensity is still unclear. In this work, a commonly used process signal, namely the electrode displacement and its instantaneous behavior when expulsion occurs are systematically studied. Based upon experiments with various electrodes and workpieces, a nonlinear relation between the weight of expelled metal and the sudden displacement drop accompanied by the occurrence of weld expulsion is observed, which is mainly influenced by electrode tip geometry but not by material strength or sheet thickness. The intrinsic relationship between this specific signal feature and the magnitude of expulsion is further explored through geometrical analysis, and a modified analytical model for online expulsion evaluation is finally proposed. It is shown that the improved model could be applied to domed electrodes with different tip geometries and varying workpieces ranging from low carbon steel to HSS. The error of expulsion estimation could be limited within ±20.4 mg (±2σ) at a 95% confidence level. This study may contribute to the online control of weld expulsion to the minimum level.

A Comparative Study of AC and MFDC Resistance Spot Welding

2004 ◽  
Author(s):  
Wei Li ◽  
Daniel Cerjanec
Keyword(s):  
Comparative Study ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Welding Current ◽  
Median Frequency ◽  
Resistance Spot ◽  
Secondary Voltage ◽  
Nugget Growth ◽  
Welding Processes

This paper presents a comparative study of the AC and MFDC resistance spot welding process. Two identical welders were used; one with a single phase AC and the other with a median frequency DC weld control. Both welders were instrumented such that the primary and secondary voltage and current could be collected. A nugget growth experiment was conducted to compare the weld size and energy consumption in the AC and MFDC welding processes. It is found that the MFDC process generally produces larger welds with the same welding current. However, this difference is more prominent when the welding current is low. Overall the AC welding process consumes more energy to make a same size weld. The larger the welding current is used, the less efficient the AC process becomes.

Dissimilar resistance spot welding of AISI 304 to AISI 409 stainless steels: mechanical properties and microstructural evolutions

2018 ◽  
Vol 115 (6) ◽  
pp. 610 ◽  
Author(s):  
Mehdi Safari ◽  
Hossein Mostaan ◽  
Abdoreza Ghaderi
Keyword(s):  
Stainless Steels ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Steel Sheet ◽  
Welding Current ◽  
Stainless Steel Sheet ◽  
Tensile Shear ◽  
Aisi 304 ◽  
Resistance Spot ◽  
Electrode Force

In this work, dissimilar resistance spot welding of austenitic stainless steel sheet (304 grade) and ferritic stainless steel sheet (409 grade) is studied experimentally. For this purpose, the effects of process parameters such as welding current, welding time and electrode force on tensile-shear strength of resistance spot welded joints are investigated with response surface methodology (RSM). Also, microstructural evolutions during resistance spot welding process of AISI 409 and AISI 304 stainless steels are evaluated by optical microscopy. It is concluded from results that the tensile-shear strength of spot welds is increased with increasing the welding current, welding time and electrode force. It is shown that widmanstatten ferrites have been grown in the weld metal of dissimilar resistance spot welds of AISI 304 and AISI 409 stainless steels.

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