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Showing papers on "Spot welding published in 2017"


Journal ArticleDOI
TL;DR: In this article, a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys and Al/Ti alloys with focus on structure, properties, and performance relationships is presented.
Abstract: This paper presents a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys, and Al/Ti alloys, with focus on structure, properties, and performance relationships. It also includes weld bonding, effect of welding parameters on joint quality, main metallurgical defects in Al spot welds, and electrode degradation. The high contact resistance, induced by the presence of oxide layer on the surface of Al alloys, and the need for application of high welding current during RSW of Al alloys result in rapid electrode tip wear and inconsistency in weld quality. Studies have shown that cleaning the oxide layer, sliding of a few microns between sheets, enhancing the electrode force, and the application of a low-current pre-heating can significantly reduce the contact resistance and improve joint quality. For Al/steel dissimilar RSW, the technique of resistance element welding, the use of optimized electrode morphology, the technique of RSW with cover plates, and the use of interlayers such as Al-Mg, AlSi12, and AlCu28 alloys were found to suppress the formation of brittle intermetallic compounds (IMC) and improve the joint quality. The employment of pure Ni foil, Au-coated Ni foil, Sn-coated steel, and Zn-coated steel interlayers was also found to restrict the formation of brittle IMCs during RSW of Al/Mg alloys. Furthermore, the techniques of RSW with cover plates and RSW under the influence of electromagnetic stirring effect were found to improve the weldability of Al/Ti dissimilar alloys.

123 citations


Journal ArticleDOI
TL;DR: In this paper, ultrasonic metal welding has been applied for joining aluminum AA5754 sheets to a thermoset matrix composite consisting in a carbon fiber reinforced epoxy resin (CF/epoxy).

87 citations


Journal ArticleDOI
TL;DR: In this paper, a keyhole closure process in high-strength AlZnMg(Cu) alloys, refill friction stir spot welding was used to perform repair welds of through holes of 7.5mm diameter in AA 7075-T651 plates with 6mm thickness.

85 citations


Journal ArticleDOI
TL;DR: In this article, two types of intermetallic compound (IMC) layers at the interface of Al-steel joints generated by resistance spot welding (RSW) processes are characterized and discussed.

80 citations


Journal ArticleDOI
TL;DR: In this article, a 3-factor, 3-level comprehensive test was carried out on aluminum-steel dissimilar alloys to investigate the influences of welding parameters on joint strength.

78 citations


Journal ArticleDOI
TL;DR: In this paper, a critical assessment highlights the current understating regarding factors affecting the joint properties and approaches to control the interfacial reaction and unresolved scientific challenges are discussed with the goal of shedding light on the path forward to produce reliable metallurgical bonding between aluminium and steels for automotive application.
Abstract: Dissimilar joining of aluminium and steel, especially using resistance spot welding as a critical process in vehicle manufacturing, is a key challenge for multi-materials lightweight design strategy. Controlling the formation and growth of Al5Fe2 intermetallic is the outstanding issue for producing high strength crash-resistance Al/steel dissimilar resistance spot welds. This critical assessment highlights the current understating regarding factors affecting the joint properties and approaches to control the interfacial reaction. Finally, the unresolved scientific challenges are discussed with the goal of shedding light on the path forward to produce reliable metallurgical bonding between aluminium and steels for automotive application.

76 citations


Journal ArticleDOI
TL;DR: In this paper, a refill friction stir spot welding (RFSSW) was used to weld 2 mm-thick 5083-O alloy and three fracture modes were obtained during the lap shear test and all were affected by the hook defect.

74 citations


Journal ArticleDOI
TL;DR: In this article, an AZ31 Mg alloy and 316L austenitic stainless steel (ASS) were joined via resistance spot welding (RSW) and resistance element welding (REW).

72 citations


Journal ArticleDOI
TL;DR: In this article, the microstructural evolution of resistance spot welded 1000MPa dual phase steel under two different welding conditions, and their relation to the mechanical performance and failure mechanisms are reported.

72 citations


Journal ArticleDOI
TL;DR: In this article, solid-state ultrasonic spot welding (USW) was used to join Al alloy 6111-T4 to galvanized high-strength low-alloy (HSLA) steel at different welding energy levels.

59 citations


Journal ArticleDOI
TL;DR: In this paper, the double pulse welding was used to partially remelt the primary weld nugget and anneal the area at the fusion boundary of the Nugget, and the effects of the annealing treatment on the segregation and the microstructure have been studied by electron probe microanalysis and electron backscatter diffraction (EBSD).
Abstract: The effects of single and double pulse resistance spot welding on the microstructures of an advanced high strength automotive steel are presented in this work. The double pulse welding schemes partially remelt the primary weld nugget and anneal the area at the fusion boundary of the nugget. The effects of the annealing treatment on the segregation and the microstructure have been studied by electron probe microanalysis (EPMA) in combination with electron backscatter diffraction (EBSD). Results show that phosphorus has been redistributed at the primary weld nugget edge of the double pulse welds, while the mean block width and ellipticity of the prior austenite grains were smaller in welds subjected to double pulsing compared with single pulse weld. A favourable failure mode was obtained for the double pulse welds although behaviour did not correlate with the measured grain size.

Journal ArticleDOI
TL;DR: In this paper, AA5754 Al alloy and coated steel were successfully joined by refill friction stir spot welding through the eutectic Al-Si coating, the overlap shear strength increased with plunge depth and reached a high strength plateau which was attributed to maximum bonding size and strong Al/AlSi joint interface.

Journal ArticleDOI
TL;DR: In this paper, ultrasonic echo signals of four kinds of stainless steel resistance spot welds, namely failed weld, stick weld, good weld, and defective weld with gas pore, are analyzed in the time domain, frequency domain, and time-frequency domain based on wavelet packet transform.
Abstract: In this paper, ultrasonic echo signals of four kinds of stainless steel resistance spot welds, namely failed weld, stick weld, good weld, and defective weld with gas pore, are analyzed in the time domain, frequency domain, and time-frequency domain based on wavelet packet transform. Fourteen ultrasonic characteristic signals which can reflect the different kinds of spot welds are extracted and can be automatically identified and classified by back-propagation (BP) neural network. The method of this paper can realize the intelligent identification of resistance spot welding defects, and the feasibility of this method has been verified in the experiment.

Journal ArticleDOI
TL;DR: In this article, the microstructure and performance relationship in resistance spot welding of a martensitic advanced high strength steel was investigated and significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HZ, with the latter plays more important role in mechanical properties of the spot welds.
Abstract: The paper addresses the process–microstructure–performance relationships in resistance spot welding of a martensitic advanced high strength steel. Significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HAZ (SCHAZ), with the latter plays more important role in mechanical properties of the spot welds. The strain concentration associated with the HAZ softening promotes initiation of pullout failure from the soft SCHAZ. While, the peak load in the interfacial failure mode is governed by the fusion zone size, that of the pullout mode is significantly affected by the HAZ softening. To improve weldability of martensitic steels, the HAZ softening should be minimised via modifications in welding process or steel chemistry.

Journal ArticleDOI
TL;DR: In this paper, the microstructure in the fusion zone (FZ) was determined to be full lath martensite because of the high cooling rate, and the tensile-shear strength of the welded spot experienced two stages of a notable increase and a subsequent decrease.

Journal ArticleDOI
TL;DR: In this paper, the strength and fracture toughness of AISI420 martensitic stainless steel resistance spot welds under the tensile-shear loading was analyzed by quasi-cleavage interfacial failure.
Abstract: The paper is focused on the strength and fracture toughness of AISI420 martensitic stainless steel resistance spot welds under the tensile-shear loading The failure behavior of AISI420 spot welds was featured by quasi-cleavage interfacial failure with low load bearing capacity and weak energy absorption capability which was a function of the weld fusion microstructure, predominately carbon and chromium rich martensite plus δ-ferrite Fracture toughness of the fusion zone proved to be the most important factor controlling the peak load of the spot welds made on AISI420 failed in interfacial mode A geometry-independent fracture toughness of the weld nugget (ca 23 MPam05) was determined using fracture mechanics concept Through modeling it was found that there is a critical fracture toughness which beyond that the pullout failure mode can be obtained which is a function of sheet thickness and tensile strength of the base metal

Journal ArticleDOI
TL;DR: In this paper, a new refill friction spot welding process called Threaded Hole Friction Spot Welding (THFSW) was introduced to join AA5052 aluminum to short carbon-fiber-reinforced polypropylene composite sheets.

Journal ArticleDOI
J.Y. Cao1, Min Wang1, Lingchi Kong1, H.X. Zhao, P. Chai 
TL;DR: In this article, the evolution of microstructure, texture and mechanical properties during refill friction stir spot welding (RFSSW) of 6061-T6 alloy was investigated.

Journal ArticleDOI
TL;DR: In this paper, an efficient quality monitoring system in small scale resistance spot welding based on dynamic resistance was developed, where the dynamic resistance variation was related to weld nugget formation process.

Journal ArticleDOI
TL;DR: The balancing problem of robotic spot welding manufacturing lines is presented and modeled based on a real-world car factory on the outskirts of Curitiba, Brazil, and the optimized balancing achieved a cycle time reduction of up to 6.6% compared to the as-is configurations.

Journal ArticleDOI
TL;DR: In this article, a review of the published models for the electrical contact resistance in the resistance spot welding process is presented and an inclusive comparison of the models is presented, where the combined effects of both constriction and film are considered as general models.
Abstract: Contact resistance is a complicated phenomenon and resistance welding significantly escalates its complexity. Interference of various parameters in resistance spot welding, despite extensive research in this field, still makes this process puzzling to the welding researchers. Various models have been developed to deal with the contact resistance, but more or less all of them end up with trial and error to yield an acceptable outcome. Quantifying the contact resistance is a critical problem in the modeling of the resistance spot welding. In this paper, the published models for the electrical contact resistance in the resistance spot welding process are reviewed. Since the total or dynamic electrical resistance is composed of bulk resistance and contact resistance, it is realized that contact resistance is the most essential factor in heat generation. The contact resistance, by itself, is composed of two parts, constriction resistance and film resistance. Some models have been proposed to explain the relationship for constriction resistance of a single point, while some of the other models have dealt with a number of points. In contrast with constriction resistance, few formulations have been suggested for film resistance. Meanwhile, in some models, the combined effects of both constriction and film are considered as general models. One key observation can be drawn from these studies, and it is that reported measurements have shown obvious discrepancies. Contact resistance modeling for simulation of resistance spot welding depends on the modeling of contact resistance after film breakdown. Therefore, mathematical modeling of the constriction resistance is the key to a comprehensive model of the contact resistance. Despite valuable studies that mainly are experimental, generally recognized model of contact resistance that can take into account all of the important influencing parameters has not been developed yet. This might be resulted from the complexity of contact resistance. In the previous studies, analysis of contact resistance is mostly qualitative rather than quantitative, because the performance of the films differs extensively. The major way to study the influence of diverse films has been experimental investigations. The electrical contact involves problematical interaction between contact members of complex geometry and it is not easy to model. Only for the constriction resistance of some simplified cases analytical models are available. In resistance spot welding, understanding the surface conditions, such as size, quantity, and distribution of contacting asperities, is very hard to find. Moreover, it is difficult to explain and describe the surface films precisely. Although the theoretical investigations have been provided for a long time, a useful and systematic model of dynamic resistance has not been presented yet. To provide the researchers in resistance spot welding and other related fields with a comprehensive account of contact resistance, this article reviews and analyzes the published works in this area. Also, an inclusive comparison of the models is presented.

Journal ArticleDOI
TL;DR: In this article, the effect of various control parameters like electrode tip diameter, welding current, and heating cycle on the nugget size and tensile shear strength of dissimilar metal spot welding of 2-mm-thick AISI 316L austenitic stainless steel and 2205 Duplex Stainless Steel sheets was determined.
Abstract: Resistance spot welding (RSW) involves joining of contacting surfaces by heat generated by resistance to electric current . The process is swift and finds demand in automobile industries for mass production. In spite of all the assets of the process, it yields a poor quality welds and inferior weld strength at the inner region of the joint interface. This may be improved by accurate setting of control parameters. The objective of this study is to determine the effect of various control parameters like electrode tip diameter, welding current, and heating cycle on the nugget size and tensile shear strength of dissimilar metal spot welding of 2-mm-thick AISI 316L austenitic stainless steel and 2205 Duplex Stainless Steel sheets. The Taguchi’s L27 orthogonal array (OA) design is selected to conduct the experimental spot welding trials on the dissimilar materials. Subsequently, the specimens are examined usinganalysis of variance (ANOVA) technique to customize optimal parameter setting to obtain high tensile strength and favorable weld quality characteristics. The results reveal that welding current is the most dictating factor to achieve highest tensile strength with superior weld quality. Also, weld samples are prepared for metallographic examination from cross section areas of resistance spot welds to examine microstructure changes and ferrite content measurement in different regions of weld nugget. The microstructure examination shows that the weld nugget consists of ferrite and austenite and ferrite and there is no precipitate of detrimental phases in the weldment.

Journal ArticleDOI
TL;DR: In this paper, the microstructure and texture of the original and welded samples have also been investigated via scanning electron microscope (SEM), Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM).

Journal ArticleDOI
TL;DR: In this article, a keyhole refilled Friction Stir Spot Welding (FSSW) process is developed for joining aluminum alloy 6061 to Transformation Induced Plasticity (TRIP) steel.

Journal ArticleDOI
TL;DR: In this article, the effect of welding process parameters on the shear strength, tensile strength, nugget diameter and the observed failure mode was analyzed for galvannealed high strength interstitial free steel sheets of 1.6mm thickness.

Journal ArticleDOI
TL;DR: In this paper, a lap-joint configuration with the steel positioned on top of the aluminium and with a texture faced down to the aluminium surface was investigated to increase the maximum tensile shear load of the Fe-Al joints.

Journal ArticleDOI
TL;DR: In this paper, the effect of a plasma electrolytic oxidation (PEO) pre-treatment on joining of AA 5052 aluminium alloy and polypropylene by friction stir spot welding (FSSW) is investigated using lap tensile shear tests.
Abstract: The effect of a plasma electrolytic oxidation (PEO) pre-treatment on joining of AA 5052 aluminium alloy and polypropylene by friction stir spot welding (FSSW) is investigated using lap tensile shear tests. Two surface conditions of the AA 5052 alloy are compared, one with a PEO pre-treatment in a silicate-based electrolyte, another without any pre-treatment. The resultant specimens are examined by high resolution scanning electron microscopy, thermogravimetric analysis and attenuated total reflectance-infrared spectroscopy. The PEO treatment generated a thermally-insulating, porous ceramic coating, which has a highly porous, rough surface that is favourable for incorporating polypropylene melted by FSSW. The pre-treatment significantly increased the lap tensile shear strength, by about a factor of three, in comparison with the untreated alloy, suggesting that open pores in the coating filled by polypropylene provide strong micromechanical interlocking and covalent bonding between the coated alloy and the polymer.

Journal ArticleDOI
Jun Cao1, Min Wang1, Lingchi Kong1, Y. H. Yin, L. J. Guo 
TL;DR: In this paper, the Johnson-Cook equation was used to describe the dependence of stress on temperature, strain, and strain rate during friction spot welding (FSpW) of the aluminum alloy Al 6061-T6.
Abstract: Material flow during friction spot welding (FSpW) of the aluminum alloy Al 6061-T6 was examined by a combination of numerical modeling and experimentation. The finite element model was developed according to coupled Eulerian-Lagrangian formulations, where the Johnson-Cook equation was used to describe the dependence of stress on temperature, strain, and strain rate. The modeling results revealed that the hook defect was formed due to the insufficient material deformation and low material diffusion rate. A model of the material flow in FSpW was developed based on the numerical and experimental results. The onion structure near the sleeve periphery was formed during the plunge stage when materials beside and below the sleeve were combined.

Journal ArticleDOI
TL;DR: In this paper, the combined effect of resistance spot welding (RSW) and precipitation hardening on tensile shear load bearing capacity (TSLBC) of A286 superalloy was studied.
Abstract: This work aims to study the combined effect of resistance spot welding (RSW) and precipitation hardening on tensile shear load bearing capacity (TSLBC) of A286 superalloy. The tensile shear test specimens were welded in the solution treated condition, and then subjected to different precipitation hardening treatments. The impoverishment in Ti, due to its segregation towards the interdendritic region (studied by performing SEM/EDX analysis), causes the development of gamma prime depleted zones in the dendrite core of the weld nugget, which is associated with a decrease of the mechanical properties with respect to the base metal. The segregation of Ti towards the interdendritic region of the weld nugget has also influence on the eta phase formation, which appears later (with longer aging times) in the weld nugget than in the base metal. The aging time at which the maximum experimental TSLBC is reached is, for both aging temperatures, 100 h. The experimental TSLBC of the tensile shear test specimens hardened at lower aging temperature is greater (except for the shortest aging time) than that of those hardened at higher aging temperature.

Book
08 Sep 2017
TL;DR: In this paper, the authors provide a comprehensive resource for automotive engineers and technicians who work with modern spot welding equipment and automotive materials including advanced high-strength steels, coated steels and aluminum alloys.
Abstract: The early chapters of this book provide thorough coverage of resistance spot welding fundamentals and principles. Topics covered include lobe and current range curves, contact resistance vs. electrode force, dynamic resistance, heat balance, nugget growth, etc. Equipment issues such as machine types, power supplies, and electrodes are addressed. Subsequent chapters focus on specific spot welding challenges to modern automotive manufacturing. Approaches to welding modern materials including advanced high-strength steels, coated steels, and aluminum alloys are covered in much detail. The final chapters focus on many common production and quality control issues, such as electrode wear, monitoring and testing, computational modeling, and welding codes. The overall goal of the book is to provide a comprehensive resource for automotive engineers and technicians who work with modern spot welding equipment and automotive materials. Table of Contents: Preface / Introduction to Resistance Spot Welding / Re...