Showing papers on "Spot welding published in 2014"
TL;DR: In this article, the basic principles of friction stir welding (FSW) are discussed, including terminology, material flow, joint configurations, tool design, materials, and defects, with an emphasis on recent advances in aerospace, automotive, and ship building.
393 citations
TL;DR: In this paper, the microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature are discussed in detail in order to highlight the correlations between weld parameters used during FSW and the micro-structures evolved in the weld region and thus mechanical properties.
Abstract: The diversity and never-ending desire for a better life standard result in a continuous development of the existing manufacturing technologies. In line with these developments in the existing production technologies the demand for more complex products increases, which also stimulates new approaches in production routes of such products, e.g., novel welding procedures. For instance, the friction stir welding (FSW) technology, developed for joining difficult-to-weld Al-alloys, has been implemented by industry in manufacturing of several products. There are also numerous attempts to apply this method to other materials beyond Al-alloys. However, the process has not yet been implemented by industry for joining these materials with the exception of some limited applications. The microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature will be discussed in detail in this review. The correlations between weld parameters used during FSW and the microstructures evolved in the weld region and thus mechanical properties of the joints produced will be highlighted. However, the modeling studies, material flow, texture formation and developments in tool design are out of the scope of this work as well as the other variants of this technology, such as friction stir spot welding (FSSW).
325 citations
TL;DR: In this paper, the authors applied FSpW to join the 6061-T4 aluminum alloy sheet with 2mm thickness and found that the tensile/shear strength reached the maximum of 7117.0 and 4555.4 N at the welding condition of the rotational speed of 1500rpm and duration time of 4 s.
110 citations
TL;DR: In this paper, two kinds of ultra-high strength steel sheets having different ductility were used to join two different types of die having different shape and diameter and depth of the die.
103 citations
TL;DR: In this article, the effect of welding current at constant welding time was considered on the weld properties such as weld nugget size, tensile-shear load bearing capacity of welded materials, failure modes, failure energy, ductility, and microstructure of weld nuggets as well.
102 citations
23 Jun 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of the Zn interlayer on the micro-structural and mechanical properties of weld joints was analyzed using X-ray spectroscopy and diffraction scans, and it was determined that welds with a Zninterlayer placed in-between the faying surfaces of the base metals formed a composite-like eutectic structure of Al and Al 2 Cu at the center and Al-Zn and CuZn 5 at the edges of the welded joint.
Abstract: Dissimilar aluminum (Al) and copper (Cu) metals were joined together using ultrasonic spot welding (USW), a solid state welding technology. The welds were made with and without a zinc (Zn) interlayer to study the microstructural and mechanical properties of weld joints to analyze the effect of the Zn interlayer. USWed Al-to-Cu joints did not produce any intermetallic compounds (IMCs), and only swirls and voids were observed. It was determined through energy dispersive X-ray spectroscopy and X-ray diffraction scans that welds with a Zn interlayer placed in-between the faying surfaces of the base metals formed a composite-like eutectic structure of Al and Al 2 Cu at the center and Al–Zn and CuZn 5 at the edges of the welded joint. Al–Cu joints welded with a Zn interlayer in-between displayed lap shear tensile strengths 25–170% greater than those of the welds without any interlayer.
100 citations
TL;DR: In this article, the microstructure of the fusion zone and the heat affected zone is investigated in resistance spot welding of AISI 430 ferritic stainless steels and the phase transformations which occur during weld thermal cycle were analyzed in details, based on the physical metallurgy of welding of the ferritic steels.
92 citations
TL;DR: In this paper, the optimal welding parameters for friction stir spot welded AA3003-H12 aluminum alloy sheets using a Taguchi orthogonal array were determined using a randomised approach, and the individual importance of each parameter on the tensile shear load of the FSSW joints was evaluated by examining the signal-to-noise ratio and analysis of variance (ANOVA) results.
90 citations
TL;DR: Friction stir spot welding (FSSW) is a very useful variant of the conventional friction stir welding (FSW), which shows great potential to be a replacement of single-point joining processes like resistance spot welding and riveting.
Abstract: Friction stir spot welding (FSSW) is a very useful variant of the conventional friction stir welding (FSW), which shows great potential to be a replacement of single-point joining processes like resistance spot welding and riveting. There have been many reports and some industrial applications about FSSW. Based on the open literatures, the process features and variants, macro- and microstructural characteristics, and mechanical properties of the resultant joints and numerical simulations of the FSSW process were summarized. In addition, some applications of FSSW in aerospace, aviation, and automobile industries were also reviewed. Finally, the current problems and issues that existed in FSSW were indicated.
87 citations
TL;DR: In this article, the effects of interlayer thickness on microstructure and mechanical properties of welded joints were studied and the welded joint with interlayer employed could be recognized as a brazed joint.
85 citations
10 Jan 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the authors performed friction spot welding or refill friction stir spot welding to consolidate dissimilar AA5754 Al and AZ31 Mg alloys and found that the material flow induced by tool movement plays an important role in both the distribution of the intermetallic compounds and the interfacial area between the base materials.
Abstract: In the present study, friction spot welding or refill friction stir spot welding was performed to consolidate dissimilar AA5754 Al and AZ31 Mg alloys. The intermetallic compounds of Al12Mg17 and Al3Mg2 were primarily found in the weld, distributed at the interface between the base materials and in the Al top sheet. The distribution of the intermetallic compounds and the interfacial area between the base materials affect the lap shear strength of the weld. It is concluded that the material flow induced by tool movement plays an important role in both the distribution of the intermetallic compounds and the interfacial area between the base materials.
Patent•
24 Jan 2014
TL;DR: In this paper, a method of resistance spot welding to join a plurality of overlapping metal sheets is proposed, including dividing a current pattern into two or more steps for welding, and when a time variation amount of an instantaneous amount of heat generated deviates during any step from the time variation curve by a difference, performing adaptive control welding to control a current passage amount in order to compensate for the difference during a remaining welding time.
Abstract: Proposed is a method of resistance spot welding to join a plurality of overlapping metal sheets, including: dividing a current pattern into two or more steps for welding; before actual welding, performing test welding to store, for each step as a target value, a time variation of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume; and subsequently, as actual welding, starting welding using, as a standard, a time variation curve of the instantaneous amount of heat generated per unit volume obtained by the test welding, and when a time variation amount of an instantaneous amount of heat generated deviates during any step from the time variation curve by a difference, performing adaptive control welding to control a current passage amount in order to compensate for the difference during a remaining welding time in the step.
TL;DR: In this article, the effects of welding time and natural aging on peak load and fracture energy of welded aluminum alloy AA6111 and TiAl6V4 dissimilar alloys were investigated.
TL;DR: In this article, the effects of the RSW parameters on weld properties were investigated within a design of experiments framework by altering the electrical current intensity, welding time, sheet thickness, electrode face radius, and squeeze force at multiple levels.
TL;DR: In this article, cold metal transfer (CMT) spot plug joining of 1mm thick Al AA6061-T6 to 1.5mm thick galvanized steel (i.e., Q235) was studied.
TL;DR: In this paper, experiments were made for welding current variation between 6kA and 12kA, and the effect of welding current on micro-properties was very slight while nugget size was highly dependent on welding current.
TL;DR: In this paper, a double phase 980 MPa grade (DP980) steel sheets were resistance spot welded using a pulsed current, and the effects of the pulsed currents on the strength properties of the joints were investigated.
Abstract: Dual phase 980 MPa grade (DP980) steel sheets were resistance spot welded using a pulsed current, and the effects of the pulsed current on the strength properties of the joints were investigated. The pulsed current improved the mechanical properties of the joints in cross tensile tests. In situ observations during tear tests revealed that the ductility of the nugget was improved and that the propagation of cracks into the nugget was inhibited when the pulsed current was used. Microstructural observations and electron probe microanalysis (EPMA) of the nugget showed that the segregation of phosphorus at the nugget was reduced in the joint welded using the pulsed current, suggesting that the pulsed current improved the ductility of the nugget by altering their microstructures.
TL;DR: In this article, the authors describe the modeling and testing of structural elements by application of an angle bar and spot welding techniques with the introduction of adhesive layers between adherends, and the failure of the specimens took place when the adhesive layer was almost totally degraded and the welded spots were subjected to intensive plastic degradation.
TL;DR: In this paper, solid-state ultrasonic spot welding (USW) was used to join Al/Mg/Al tri-layered clad sheets, aiming at exploring weldability and identifying failure mode in relation to the welding energy.
TL;DR: In this paper, the microstructural change, lap shear tensile load, and fatigue resistance of dissimilar ultrasonic spot-welded joints of aluminum-to-galvanized high-strength low-alloy (HSLA) steel was evaluated.
Abstract: The structural applications of lightweight aluminum alloys inevitably involve dissimilar welding with steels and the related durability issues. This study was aimed at evaluating the microstructural change, lap shear tensile load, and fatigue resistance of dissimilar ultrasonic spot-welded joints of aluminum-to-galvanized high-strength low-alloy (HSLA) steel. Two non-uniform layers were identified in between Al and HSLA steel via SEM/EDS and XRD. One was an Al-Zn eutectic layer and the other was a thin (<2 μm) layer of intermetallic compound (IMC) of Al and Fe in the nugget zone. The lap shear tensile testing gave a maximum load of 3.7 kN and the sample failed initially in between the Al-Zn eutectic film and Al-Fe IMC, and afterward from the region containing Al on both matching fracture surfaces. The fatigue test results showed a fatigue limit of about 0.5 kN (at 1 × 107 cycles). The maximum cyclic stress at which transition of the fatigue fracture from transverse through-thickness crack growth mode to the interfacial failure mode occurs increases with increasing energy input.
TL;DR: In this paper, the effect of external magnetic field (EMF) on the RSW process of aluminum alloy under different welding parameters has been studied and the effects of the EMF on weld size, tensile shear force, microstructure, and microhardness have been systematically discussed.
TL;DR: In this article, the eutectic constituent of cracks was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation, which showed that cracks have less/no significant effect on the static cross-tensile strength and the tensile-shear strength.
TL;DR: In this paper, the feasibility of friction spot welding of a commercial poly(methyl methacrylate) (PMMA) GS grade and a PMMA 6-N/2-wt% silica (SiO2) nanocomposite was investigated.
TL;DR: In this paper, a novel technology was developed for the arc spot welding of AZ31-Mg alloy to Q235 steel with Cu as interlayer, which resulted in two bonding mechanisms: weld-brazing by the Cu transition layer at the interface edge and bonding by a micron-scale composite transition layer of Al3Cu4Fe3 and Fe4Cu3 intermetallic phases.
17 Nov 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructural evolution of spot welded AZ31, AZ61 and AZ80 magnesium alloys was studied via optical and scanning electron microscopy, and it was found that the increasing amount of β-Mg17(Al,Zn)12 phase in the heat affected zone (HAZ) and fusion zone (FZ) resulted in the reduction of the tensile shear strengths of the AZ61, AZ80 welds compared to those of AZ31 welds.
Abstract: The microstructural evolution of the spot welded AZ31, AZ61 and AZ80 magnesium alloys was studied via optical and scanning electron microscopy. As the Al content of the magnesium base alloy increased from 3 wt% (AZ31) to 6% (AZ61) and 8% (AZ80), columnar to equi-axed dendrite transition and grain refinement in the fusion zone were enhanced. However, the increasing amount of the β-Mg17(Al,Zn)12 phase in the heat affected zone (HAZ) and fusion zone (FZ) resulted in the reduction of the tensile shear strengths of the AZ61 and AZ80 welds compared to those of AZ31 welds. Moreover, in the tensile-shear testing, the AZ61 and AZ80 welds failed in the heat affected zone along the fusion boundary, because micro-cracking occurred preferentially at the interfaces between β particles and Mg matrix. Post-weld solutionizing treatment was found to significantly reduce the quantity of β particles in heat affected and fusion zones of AZ61 and AZ80 welds. This led to an increase in the weld strengths of AZ61 and AZ80 alloys because the heat treatment eliminated the β particles and cracks propagated into the coarse-grained heat affected zone and then base material. For the heat treated welds, grain size was found as a major factor in the failure mode.
TL;DR: In this paper, the failure mode and failure mechanism of the dissimilar thickness dual phase sheets resistance spot welding joints was investigated, and three distinct failure modes were observed during the tensile shear test: interfacial, partial interfacial and pullout failure.
TL;DR: In this article, the effects of the properties of metallic coating layers on heat development and nugget growth during resistance spot welding were investigated by investigating the effect of metallic coatings on the weldability of hot-stamped boron steel.
Abstract: Aluminum-silicon-based and zinc-based metallic coatings have been widely used for hot-stamped boron steel in automotive applications. In this study, resistance spot weldability was explored by investigating the effects of the properties of metallic coating layers on heat development and nugget growth during resistance spot welding. In the case of the aluminum-silicon-coated hot-stamped boron steel, the intermetallic coating transformed into a liquid film that covered the faying interface. A wide, weldable current range was obtained with slow heat development because of low contact resistance and large current passage. In the case of the zinc-coated hot-stamped boron steel, a buildup of liquid and vapor formation under large vapor pressure was observed at the faying interface because of the high contact resistance and low vaporization temperature of the intermetallic layers. With rapid heat development, the current passage was narrow because of the limited continuous layer at the faying interface. A more significant change in nugget growth was observed in the zinccoated hot-stamped boron steel than in the aluminum-silicon-coated hot-stamped boron steel.
Patent•
06 Mar 2014
TL;DR: In this article, an indirect spot welding is proposed for welding members including at least two overlapping steel sheets that have a ferrite phase as the main phase by holding a welding electrode (23) against a steel sheet (21) from one side while applying pressure with the electrode, attaching a feeding point (24) to the steel sheet at the other side at a location remote from the welding electrode, and allowing current to flow between the electrode and the feeding point, regardless of the rigidity of the members.
Abstract: This indirect spot welding is for welding members including at least two overlapping steel sheets that have a ferrite phase as a main phase by holding a welding electrode (23) against a steel sheet (21) from one side while applying pressure with the electrode (23), attaching a feeding point (24) to a steel sheet (22) at the other side at a location remote from the electrode (23), and allowing current to flow between the electrode (23) and the feeding point (24). This welding includes contacting magnetic rigid bodies (26-1, 26-2) to a peripheral area of the electrode (23) from the one side against which the electrode (23) is held and securing an overlapping region in the peripheral area of the electrode (23) by a magnetic force produced by the rigid bodies (26-1, 26-2), thereby obtaining a weld having fully satisfactory strength, regardless of the rigidity of the members.
TL;DR: In this article, the effect of electromagnetic stirring (EMS) on the nugget formation, microstructure, and mechanical properties of magnesium alloy resistance spot weld (RSW) was investigated.
TL;DR: In this paper, the microstructure and mechanical properties of spot welds were evaluated using metallographic technique, microhardness and tensile shear tests, and the results showed that the tendency to fail in the pullout mode increased in the order of DP/DP, TRIP/TRIP and DP-TRIP welds, which was caused by the different hardness distribution, carbon equivalent and susceptibility to shrinkage void formation of spot weldings for different combinations.
Abstract: Similar and dissimilar combinations of a 1000 MPa galvanised dual phase (DP) steel and a 980 MPa transformation induced plasticity (TRIP) steel were resistance spot welded under different welding and heat treatment parameters. The microstructure and mechanical properties of spot welds were evaluated using metallographic technique, microhardness and tensile shear tests. The results showed that the tendency to fail in the pullout mode increased in the order of DP/DP, TRIP/TRIP and DP/TRIP welds, which was caused by the different hardness distribution, carbon equivalent and susceptibility to shrinkage void formation of spot welds for different combinations. In the study of the effects of heat treatments on the DP/TRIP welds, the pre-heating procedure improved the splash of welding to some extent. When the cooling time was larger than or equal to 1000 ms, the post-heating procedure improved the mechanical properties of spot welds owing to the temper of spot weld microstructure.