Factors Affecting Nugget Growth With Mushy-Zone Phase Change During Resistance Spot Welding

1991 ◽  
Vol 113 (3) ◽  
pp. 643-649 ◽  
Author(s):  
P. S. Wei ◽  
F. B. Yeh
Keyword(s):  
Mushy Zone ◽  
Phase Change ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Maximum Velocity ◽  
Temperature Fields ◽  
Factors Affecting ◽  
Resistance Spot ◽  
Nugget Growth ◽  
Cooling Effects

An unsteady, axisymmetric model is first proposed to investigate extensively effects of the physical, thermal, and metallurgical properties and welding conditions on nugget growths with mushy-zone phase change during resistance spot welding. The electromagnetic force, joule heat and interfacial heat generation, and cooling effects of electrodes are taken into account. Fluid patterns, temperature fields, and solute distributions in the liquid, solid, and mushy zones are determined. Results show that the computed nugget growths and temperature fields are consistent with experimental data. Variations of properties strongly affect the nugget growth. The maximum velocity in the weld nugget is found to be small and around 5 mm/s.

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.

Simulating Thermoelectric Effect and Its Impact on Asymmetric Weld Nugget Growth in Aluminum Resistance Spot Welding

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Lin Deng ◽  
YongBing Li ◽  
Wayne Cai ◽  
Amberlee S. Haselhuhn ◽  
Blair E. Carlson
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Weld Nugget ◽  
Thermoelectric Effects ◽  
Element Analysis ◽  
Resistance Spot ◽  
Seebeck Coefficients ◽  
Nugget Growth ◽  
Simulation Results ◽  
The Impact

Abstract Resistance spot welding (RSW) of aluminum–aluminum (Al–Al) is known to be very challenging, with the asymmetric growth of the weld nugget often observed. In this article, a semicoupled electrical–thermal–mechanical finite element analysis (FEA) procedure was established to simulate the RSW of two layers of AA6022-T4 sheets using a specially designed Multi-Ring Domed (MRD) electrodes. Critical to the modeling procedure was the thermoelectric (including the Peltier, Thomson, and Seebeck effects) analyses to simulate the asymmetric nugget growth in the welding stage. Key input parameters such as the Seebeck coefficients and high-temperature flow stress curves were measured. Simulation results, experimentally validated, indicated that the newly developed procedure could successfully predict the asymmetric weld nugget growth. Simulation results also showed the Seebeck effect in the holding stage. The simulations represent the first quantitative investigation of the impact of the thermoelectric effects on resistance spot welding.

A Microscopic Approach to Determine Electrothermal Contact Conditions During Resistance Spot Welding Process

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
P. Rogeon ◽  
R. Raoelison ◽  
P. Carre ◽  
F. Dechalotte
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Electrical Contact ◽  
Welding Process ◽  
Contact Temperature ◽  
Macroscopic Model ◽  
Contact Conditions ◽  
Imperfect Contact ◽  
Resistance Spot ◽  
Nugget Growth

This study deals with resistance spot welding process modeling. Particular attention must be paid to the interfacial conditions, which strongly influence the nugget growth. Imperfect contact conditions are usually used in the macroscopic model to account for the electrical and thermal volume phenomena, which occur near a metallic interface crossed by an electric current. One approach consists in representing microconstriction phenomena by surface contact parameters: The share coefficient and the thermal and electrical contact resistances, which depend on the contact temperature. The aim of this work is to determine the share coefficient and the contact temperature through a numerical model on a microscopic scale. This surface approach does not make it possible to correctly represent the temperature profiles, with the peak temperature, observed in the immediate vicinity of the interface and thus to define, in practice, the contact temperature correctly. That is why another approach is proposed with the introduction of a low thickness layer (third body) at the level of the interface the electric and thermal resistances of which are equivalent to the electrical and thermal contact resistance values. In this case, the parameters of the model are reduced to the thickness of the arbitrarily fixed layer and equivalent electric and thermal conductivities in the thin layer, the partition coefficient and the contact temperature becoming implicit. The two types of thermoelectric contact models are tested within the framework of the numerical simulation of a spot welding test. The nugget growth development is found to be much different with each model.

Study on Nonlinear Multiple Regression Modeling of Nugget Morphology for Unequal-Thickness Dissimilar Steel Welding

2011 ◽  
Vol 189-193 ◽  
pp. 3300-3308
Author(s):  
Yi Luo ◽  
Chang Hua Du ◽  
Chun Tian Li ◽  
Jin He Liu
Keyword(s):  
Multiple Regression ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Welding Current ◽  
Current Electrode ◽  
Factors Affecting ◽  
Dissimilar Steel ◽  
Resistance Spot ◽  
Multiple Regression Modeling

The special thermal effect makes some alterations to nugget morphology during resistance spot welding on unequal-thickness dissimilar steel. Method of nonlinear multiple orthogonal regression assembling design was introduced to design the experiment and investigate the resistance spot welding process. The indexes studied in experiments were nugget diameter and nugget deviation, which were the primary factors affecting the nugget morphology. Furthermore, four process parameters, namely welding current, electrode force, welding current duration and heat-treatment pulse current, and interactions among them were considered as the factors impacting the indexes. The nonlinear multiple regression models about nugget morphology parameters were developed on the basis of optimization. The experimental results showed that there was an effective prediction on nugget size based on the optimized models. The optimization to welding process also can be realized by the analysis to the effects of parameters and interactions.

scholarly journals Effect of Electrode Patterning on Melting Behavior and Electrode Degradation in Resistance Spot Welding of A6014-T4 Alloy

2020 ◽  
Vol 58 (12) ◽  
pp. 863-874
Author(s):  
Hyun-Uk Jun ◽  
Jae-Hun Kim ◽  
Jae Won Kim ◽  
Eun-Kyung Lee ◽  
Yang-Do Kim ◽  
...  
Keyword(s):  
Electrode Surface ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Melting Behavior ◽  
Surface Shape ◽  
Surface Design ◽  
Resistance Spot ◽  
Electrode Degradation ◽  
Effective Removal ◽  
Cooling Effects

In this study, the effects of electrode surface design on the resistance spot weldability and degradation of the electrode following resistance spot welding (RSW) of aluminum 6014-T4 alloy were investigated. A new patterning method that can be produced through repetitive pressurization was applied to the electrode, producing a lattice-like pattern shape on the resulting patterned electrode. When RSW was performed using the lattice patterned electrode, the contact resistance decreased because of the effective removal of the oxide film from the surface of the aluminum alloy. As a result, heat generated by resistance on the E/S interface was reduced. Moreover, the growth rate of the weld nuggets formed with the patterned electrode in the thickness direction was lower than that of the nuggets formed with the as-received electrode, and there was comparatively less Cu-Al alloying of the patterned electrode. In addition, a continuous RSW process was performed on the alloy to observe the effect of the electrode surface design on electrode sticking. The results indicated that electrode surface shape can significantly influence resistance heat generation and electrode cooling effects, as well as produce welds with different weld morphology and microstructure. Finally, it was proved that the patterned electrode suffered less electrode degradation through EPMA on the electrode surface after the continuous RSW was completed.

Single-Side Resistance Spot Welding Process for Joining Pipes and Sheets

2013 ◽  
Vol 7 (1) ◽  
pp. 114-119 ◽  
Author(s):  
Hitomi Nishibata ◽  
◽  
Shota Kikuchi ◽  
Manabu Fukumoto ◽  
Masato Uchihara
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Numerical Study ◽  
Welding Process ◽  
Welding Parameters ◽  
Resistance Spot ◽  
Welding Technology ◽  
Single Side ◽  
Side Resistance ◽  
Nugget Growth

This paper describes a Single-Side resistance Spot Welding (SSSW) process which is expected to be a productive welding technology for the joining of stamped sheet panels to hollow parts for auto bodies. To obtain guidelines for making a sound weld with the SSSW process, the effects of welding parameters and the alignment of specimens on nugget growth are investigated experimentally. In addition, a numerical study is carried out to discuss the mechanism of nugget growth in the SSSW process.

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