Showing papers on "Spot welding published in 2009"
TL;DR: In this paper, the tensile shear strength of the A5052/SUS304 joint was investigated using transmission electron microscopy and the reaction layer formed at its interface was observed.
219 citations
TL;DR: In this paper, the microstructural features and overlap shear strength properties of friction stir spot welds made between Al 6111 and low carbon steel, and between Mg alloy AM60 and DP600 dual phase steel, are investigated.
Abstract: The microstructural features and overlap shear strength properties of friction stir spot welds made between Al 6111 and low carbon steel, and between Mg alloy AM60 and DP600 dual phase steel, are investigated. When Al 6111 is the upper sheet in the dissimilar sandwich, completed spot welds show evidence of intermetallic layer formation and cracking. Increasing tool pin penetration into the lower sheet provided increased mechanical interlocking of the sheets due to clinching. However, increasing penetration also promoted intermetallic formation and cracking in completed welds. However, dissimilar AM60/DP600 steel friction stir spot welds produced with AM60 as the upper sheet in the dissimilar sandwich do not show evidence of intermetallic formation and cracking may be avoided by removing the zinc coating on the DP600 steel before the friction stir spot welding operation.
158 citations
TL;DR: In this paper, an interaction layer was formed between Fe and Al alloy, which was constituted by various intermetallic compounds (IMCs), which resulted in the increase in joint strength under the limited tool penetration depth (TPD).
Abstract: Dissimilar lap joints of low carbon steel and Al–Mg alloy were obtained by friction stir spot welding. Mechanically mixed layer between top and bottom plates was not formed at the weld nugget due to the limited tool penetration and the pin height of welding tool lower than the thickness of Al plate laid in top side. These welding conditions made it possible to weld steel plate using welding tools made out of a general tool steel. With increasing tool penetration depth (TPD), tensile shear force of joint increased and maximum value of 3·0 kN was obtained at the TPD of 0·5 mm, but excessive tool penetration beyond 0·5 mm was caused in a deformation of Al plate of top side. In the result of interface observation, interaction layer was formed between Fe and Al alloy, which was constituted by various intermetallic compounds (IMCs). Consequently, the size of strongly bonded area containing Fe3Al and Fe4Al13 IMCs increased with TPD, which resulted in the increase in joint strength under the limited TPD.
117 citations
TL;DR: In this article, the transition from conduction-mode laser welding to keyhole laser spot welding of titanium was studied by numerical simulation and a range of laser powers were simulated and temperature dependent evaporation recoil pressure and cooling were applied as boundary conditions on the weld pool surface.
Abstract: Weld pool transport phenomena during the transition from conduction-mode laser spot welding to keyhole laser spot welding of titanium were studied by numerical simulation. A range of laser powers were simulated and temperature dependent evaporation recoil pressure and cooling were applied as boundary conditions on the weld pool surface. Simulation results predicted a complex time-varying flow pattern during weld pool development. The surface-normal flow at the weld pool centre oscillated between upwards and downwards during the simulation time due to interaction of competing effects of evaporation recoil and surface tension pressures and laser heating and evaporation cooling. The results show that the laser weld pool flow dynamics play a key role during the transition from conduction-mode laser welding to keyhole welding.
105 citations
TL;DR: In this article, microstructure and failure behavior of galvanized low carbon steel resistance spot welds were investigated, and failure mechanism of spot weld which fail via pullout mode during tensile-shear test was localized necking in the base metal.
102 citations
TL;DR: In this article, the influence of pin length and an insulating anvil on FSSW thin (0·9 mm) 6111-T4 aluminium automotive closure panels was investigated.
Abstract: Friction stir spot welding (FSSW) is a relatively new process, which has not yet been fully optimised. The aim of the work presented was to investigate the influence of pin length and an insulating anvil on FSSW thin (0·9 mm) 6111-T4 aluminium automotive closure panels. A pinless, or 'zero pin length', tool was also tested. With a normal pin tool and a steel anvil the optimum pin length was found to be considerably shorter than conventionally used, being in the range 0·7–1 mm, as opposed to ∼1·4 mm. The insulated anvil increased the peak temperature in the bottom sheet by 45°C, but there was a 15% reduction in lap shear strength when used with a conventional pin tool. In the case of the pinless tool, successful welds were produced with comparable strengths to the highest values measured with the optimum conventional tool without a retained weld keyhole or top sheet thinning (hooking).
98 citations
TL;DR: In this article, the effect of interfacial reaction layer on the tensile strength of the joints based on the analyses of the fracture surfaces and the distribution of reaction layer thickness in the welding interface for two types of dissimilar materials joints was investigated.
95 citations
TL;DR: In this article, a non-linear multiple orthogonal regression assembling design was applied in experiment to investigate the resistance spot welding process of galvanized steel sheet used in the body manufacturing of family car.
76 citations
TL;DR: In this paper, the influence of interfacial reaction layer on the strength of resistance spot welded aluminum/steel joint was investigated by analyzing fracture surface and observing interfacial structure, and the results revealed that the interfacial strength was approximately 6.509 MPa in the case that the reaction layer thickness exceeds 1.5 µm.
76 citations
Patent•
13 Aug 2009
TL;DR: In this paper, light weight composite materials which comprise a metallic layer and a polymeric layer, the polymeric layers containing a filled thermoplastic polymer which includes a thermoplastastic polymer and a metallic fiber were formed using conventional stamping equipment.
Abstract: The present invention relates to light weight composite materials which comprise a metallic layer and a polymeric layer, the polymeric layer containing a filled thermoplastic polymer which includes a thermoplastic polymer and a metallic fiber. The composite materials of the present invention may be formed using conventional stamping equipment at ambient temperatures. Composite materials of the present invention may also be capable of being welded to other metal materials using a resistance welding process such as resistance spot welding.
75 citations
Patent•
21 Jan 2009TL;DR: In this article, the size, shape, and elevation or depths of the intrusions are determined for the formation of suitable spot welds in and between metal workpieces such as aluminum or steel panels for vehicle bodies.
Abstract: Weld faces of electrodes for resistance spot welding are formed with a suitable area of protrusions and/or intrusions. The size, shape, and elevation or depths of the protrusions or intrusions are determined for the formation of suitable spot welds in and between metal workpieces such as aluminum or steel panels for vehicle bodies. The protrusions or intrusions are also conceived and used to form an image on at least a visible surface of the welded article to produce an attractive appearance on the surface of the welded sheet.
TL;DR: In this paper, the quality level of a resistance spot welding (RSW) joint of 304 austenitic stainless steel (ASS) is estimated from its tensile shear load bearing capacity (TSLBC).
TL;DR: In this article, the tensile shear fatigue tests have been performed using resistance spot welded (RSW) joint and friction stir-spot welded joint of aluminium alloy sheets.
Abstract: Tensile shear fatigue tests have been performed using resistance spot welded (RSW) joint and friction stir spot welded (FSSW) joint of aluminium alloy sheets. When fatigue strength was characterised in terms of applied load, RSW joint showed higher fatigue strength than FSSW joint in the entire load range, while the fatigue strength normalised with respect to the nugget area was higher in FSSW joint than in RSW joint. Friction stir spot welded joint exhibited a very small scatter of fatigue life compared with RSW joint, indicating that FSSW is a very stable and reliable joining method. Macroscopic fatigue fracture modes were similar in both joints: nugget shear fracture in high applied load region and parent sheet fracture in low applied load region. It was indicated that geometrical factors around the weld zone played a dominant role in determining the fatigue strength and fracture mechanism of the joints.
TL;DR: In this paper, the performance of dissimilar material spot welds was compared with the similar ones in each of the HSLA350 and DP600 steels and exhibited different heat affected zone hardness.
Abstract: Resistance spot welding experiments were conducted on dissimilar material combination of HSLA350/DP600 steels. The welds were characterised using optical and scanning electron microscopy. The fusion zone of the dissimilar material spot weld was predominantly martensitic with some bainite. Mechanical properties were also determined by tensile shear, cross tension and fatigue tests. The performance of dissimilar material spot weld was different from that of the similar ones in each of the HSLA350 and DP600 steels and exhibited different heat affected zone hardness. The DP600 weld properties played a dominating role in the microstructure and tensile properties of the dissimilar material spot welds. However, the fatigue performance of the dissimilar welds was similar to that of the HSLA350 welds. Fatigue tests on the dissimilar material spot welds showed that the 5·5 mm diameter nugget exhibited higher fatigue strength than the 7·5 mm diameter nugget.
TL;DR: In this paper, a conventional resistance spot welding machine was used to join Mg alloy and steel by using Mg-Zn eutectic reaction, Zn layer was inserted between Mg Alloy and steel as plating on steel.
Abstract: Recently, there are strong demands for light-weight, fuel efficient cars. An effective joining technique to join light metals, such as Al and Mg alloys, with steel is required. Mg alloy and steel are especially difficult pair of metals to join. Due to not only Mg alloy's surface oxide, but also their complete phase separation nature, Mg alloy and steel do not form an intermetallic at the joint interface. We aimed to join Mg alloy and steel by using Mg-Zn eutectic reaction, Zn layer was inserted between Mg alloy and steel as plating on steel. A conventional resistance spot welding machine was used, and joint strength was evaluated by tensile strength tests. It was found that Mg alloy surface oxide are removed along with eutectic melt at low temperature, and at the same time, thin and uniform intermetallic layer of Fe-Al and Al-Mg were formed at the joint interface.
TL;DR: In this article, an experimental and numerical study was conducted to characterize laser and resistance spot welds to gain an understanding of load carrying capacity, temperature distributions and residual stress states of different joint geometries used in the automotive industry.
TL;DR: In this paper, a low transformation temperature welding wire was applied to fabrication of fillet welded T joints, and the welding angular distortion and the temperature profile of the weld metal were continuously measured during the welding process.
Abstract: A newly developed low transformation temperature welding wire, of which the transformation start temperature is lower than that of conventional welding wires, was applied to fabrication of fillet welded T joints. The welding angular distortion and the temperature profile of the weld metal were continuously measured during the welding process. The angular distortion of the fabricated T joint was reduced when the weld metal reached the martensitic transformation start temperature. The residual angular distortion was less with the low transformation temperature welding wire than that with the conventional welding wires. The welding distortion of T joints was calculated by a numerical simulation with consideration of the effect of phase transformation under weld thermal cycles. The welding distortion was reproduced with high accuracy in the numerical simulation. Results of the numerical simulation also determined that there was a direct correspondence between the transformation expansion of the weld m...
TL;DR: In this paper, the effect of the weld number on the joint strength and tool wear characteristics were analyzed by using a noncontact, 3D measurement system, scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray diffraction (XRD).
Abstract: Tool wear is a key issue for the friction stir spot welding (FSSW) of steel plates, especially in the automobile industry. In this study, steel plates were welded 500× using FSSW with WC–Co alloy tools of two different compositions. The effect of the weld number on the joint strength and the tool wear characteristics were analyzed by using a non-contact, 3D measurement system, scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). The experimental results indicated that the tool suffered extreme wear and that the joint strength was affected by the worn tool shape after welding. This tool wear was attributed to the formation of a ternary W–Fe–O compound, oxidative wear of WC and fatigue of the Co binder.
SIDI1
TL;DR: In this article, the Boubaker polynomial expansion scheme has been applied to the main system solution expressed in cylindrical coordinates and which is solved using the Householder-QR/QL algorithm.
Abstract: In this study, we are concerned with the temperature distribution inside the central nugget during a particular sequence of resistance spot welding (RSW). Numerical calculations are issued from an attempt to solve heat transfer equation inside the heated device. Boubaker polynomial expansion scheme has been applied to the main system solution expressed in cylindrical coordinates and which is solved using the Householder-QR/QL algorithm. The melting point maximal front spatial evolution has been monitored in order to make comparison with precedent results.
TL;DR: In this article, the influence of different spindle speeds and dwell times on microstructure and the mechanical properties of the weld were analyzed, and the strength of welds was evaluated both by tensile shear and vibration fatigue tests.
Abstract: Hybrid configurations between aluminium and steel are needed to meet today’s requirements for lightweight construction in the automotive industry. Different studies showed that Friction Stir Welding (FSW) as well as Friction Stir Spot Welding (FSSW) processes are suitable for joining aluminium to steel. In this work, dissimilar FSSW of aluminium AA5754 and galvanised steel HX 340LAD were examined. In particular the influence of different spindle speeds and dwell times on microstructure and the mechanical properties of the weld were analysed. In doing so, the cross-section microstructure of the weld interface was observed by light optical microscope (LOM) and scanning electron microscope (SEM). The strength of the welds was evaluated both by tensile shear and vibration fatigue tests. The influences of the individual parameters on the weld are presented in detail. The appearance of intermetallic phases (IMPs), a severe problem for conventional fusion welding processes between aluminium and steel, were investigated for the welded samples and a link to the mechanical properties is given.
Patent•
06 May 2009TL;DR: In this paper, a raised circular plateau is formed on the central axis of the dome and, in one embodiment, a suitable number of round bumps are formed in concentric spacing from adjacent the circumference of the plateau toward the circular edge of the welding face.
Abstract: Spot welding electrodes with generally dome shaped welding faces are provided with surface features for welding both aluminum alloy sheet assemblies and steel sheet assemblies. A raised circular plateau is formed on the central axis of the dome and, in one embodiment, a suitable number of round bumps are formed in concentric spacing from adjacent the circumference of the plateau toward the circular edge of the welding face. For welding steel workpieces the plateau mainly serves as the engaging feature of the electrode. Both the plateau and concentric bumps are used in penetrating light metal surfaces for suitable current passage. In another embodiment, the domed surface is shaped with concentric terraces for engagement with the workpieces.
TL;DR: In this paper, a wavelet packet transform (WPT) processing is adopted to analyze the ultrasonic signals acquired by the pulse echo from spot welds for nondestructive evaluation to the spot weld.
TL;DR: In this paper, a study was carried out on laser and resistance spot welds in overlapped sheets of dual phase advanced high strength steel (DP780) and deep drawing steel (DC04) of 2˙0 mm in thickness.
Abstract: A study was carried out on laser and resistance spot welds in overlapped sheets of dual phase advanced high strength steel (DP780) and deep drawing steel (DC04) of 2˙0 mm in thickness. The aim of the study was to investigate the fatigue performance of these joints under tensile shear loading as well as the monotonic performance for applications in the automotive industry. The mechanical properties, failure behaviour and fatigue life analyses of spot welds in similar and dissimilar joints were investigated by experimental and numerical methods. The structural stress concept was used to describe the fatigue lives of spot welded specimens. The results revealed different failure types with different fatigue behaviours for laser and resistance spot welds under the application of cyclic loads at 'high load' and 'low load' levels.
TL;DR: In this paper, the effects of nugget diameter, mode of loading and alloy chemistry have been studied on the strength of spot-welds in thin sheets of interstitial free steels.
TL;DR: In this paper, the effect of weld time and the influence of different weld atmospheres in the resistance spot weldability of AISI304 grade stainless steel deformed in tension by 5, 10, or 20 was analyzed.
TL;DR: In this article, resistance spot welding of Mg alloy AZ31 sheets was investigated in as received and acid cleaned surface conditions, and the results showed that the fracture mode of welds in the received sheets was interfacial failure while that of the acid cleaned specimens shifted from interfacial to nugget pullout and exhibited better strength.
Abstract: In this work, resistance spot welding of Mg alloy AZ31 sheets was investigated in as received and acid cleaned surface conditions. As received sheets had higher contact resistance which required lower current thresholds for weld initiation and for four root t nugget size (where t is sheet thickness). However, it also led to both serious expulsion and internal defects. The fracture mode of welds in as received sheets was interfacial failure while that of the acid cleaned specimens shifted from interfacial to nugget pullout and exhibited better strength. The acid cleaned sheets also produced less damage on electrode tip faces.
TL;DR: Wang et al. as discussed by the authors improved the weldability of dual-phase steel by adjusting the electrode force during spot welding process, and they showed that the width of weld lobe diagram can be nearly doubled.
TL;DR: In this paper, the results of the mechanical tests obtained on AA2024-T3 aluminum alloy were used to calibrate and validate a numerical model that was used to predict the joint failure mode.
Abstract: The Friction Spot Welding - FSpW is a solid-state process that allows joining two or more metal sheets in lap configuration with no residual keyhole as occurs in the Friction Stir Welding - FSW process. The present work reports part of the efforts made at GKSS Research Centre to better understand the complex phenomena that take place during FSpW of aluminum alloys and establish the mechanical response of the resulting joints. Over the recent years the research on modeling friction based welding processes has increased considerably. Most of the works related to this subject deal with the process mechanics. On the other hand, some investigations have shown how the process variables affect the mechanical properties of the joints, but it is very difficult to find quantitative results that can be readily used for mechanical design purposes. The aim of this work is to develop an analysis procedure based on the process characteristics that allows evaluating how the resulting geometry and microstructure affect the joint mechanical behavior. For this, the results of the mechanical tests obtained on AA2024-T3 aluminum alloy were used to calibrate and validate a numerical model that was used to predict the joint failure mode. The model reproduced the specimen geometry and load conditions adopted in the lap-shear and cross-tensile tests. The joint was considered as formed by three main regions (SZ - stir zone, TMAZ - thermo mechanically affected zone and HAZ - heat affected zone) whose properties and dimensions were based in microhardness evaluation and macrographic analysis of welded specimens. It was observed a good agreement between the simulation results and experimental data. The numerical modeling of the joints allows the prediction of the joint mechanical properties, as well as to understand how a change in geometry and property of each region affects the final mechanical behavior. Based in the obtained results, the analysis procedure can be easily extended to the related friction based spot processes as Friction Stir Spot Welding - FSSW.
TL;DR: In this article, the failure behavior of similar and dissimilar resistance spot welded joints of low carbon and austenitic stainless steel sheets was studied under tensile shear test with attention focused on the failure mode.
Abstract: In this paper, the failure behaviour of similar and dissimilar resistance spot welded joints of low carbon and austenitic stainless steel sheets was studied under tensile shear test with attention focused on the failure mode. Results showed that the microstructure of the fusion zone and the hardness distribution across the weld have a profound effect on the failure behaviour. Similar spot welds of stainless steel sheets exhibit the highest tendency to fail in interfacial failure mode, compared to low carbon steel similar spot welds and dissimilar low carbon and stainless steel spot welds. This behaviour is explained by the consideration of pullout failure location and hardness profile characteristics of each joint. It was shown that the failure mode transition is controlled by the hardness ratio of the fusion zone and the pullout failure location. In the case of dissimilar resistance spot welding, the hardness of the fusion zone which is governed by the dilution between two base metals, and the f...
Patent•
04 May 2009TL;DR: In this article, a method for joining dissimilar metals of a steel product and a light metal product with each other is provided, where a cavity for use in clinching the light metal products is formed, and upon the stem of the rivet is embedded into the light metals product to penetrate therethrough, light metal is caused to undergo plastic flow into the cavity of a rivet, whereupon spot welding for forming a weld nugget only within the scope of an interface between the stem and the steel product is carried out.
Abstract: There is provided method for joining dissimilar metals of a steel product (10) and a light metal product (20) with each other, wherein the light metal product and a rivet (2) made of an iron-base metal are connected with each other beforehand in a previous process preceding spot welding, and subsequently, the rivet and the steel product are spot welded with each other. Then, a cavity for use in clinching the light metal product is formed, and upon the stem of the rivet is embedded into the light metal product to penetrate therethrough, light metal (23) is caused to undergo plastic flow into the cavity (6) of the rivet, for clinching the light metal product to be thereby clinched with the rivet whereupon spot welding for forming a weld nugget only within the scope of an interface between the stem of the rivet, and the steel product is carried out.