Showing papers on "Butt welding published in 2013"

Internal defect and process parameter analysis during friction stir welding of Al 6061 sheets

Abstract: Welding parameters like welding speed, rotation speed, plunge depth, shoulder diameter etc., influence the weld zone properties, microstructure of friction stir welds, and forming behavior of welded sheets in a synergistic fashion. The main aims of the present work are to (1) analyze the effect of welding speed, rotation speed, plunge depth, and shoulder diameter on the formation of internal defects during friction stir welding (FSW), (2) study the effect on axial force and torque during welding, (c) optimize the welding parameters for producing internal defect-free welds, and (d) propose and validate a simple criterion to identify defect-free weld formation. The base material used for FSW throughout the work is Al 6061T6 having a thickness value of 2.1 mm. Only butt welding of sheets is aimed in the present work. It is observed from the present analysis that higher welding speed, higher rotation speed, and higher plunge depth are preferred for producing a weld without internal defects. All the shoulder diameters used for FSW in the present work produced defect-free welds. The axial force and torque are not constant and a large variation is seen with respect to FSW parameters that produced defective welds. In the case of defect-free weld formation, the axial force and torque are relatively constant. A simple criterion, (a,tau/a,p)(defective) > (a,tau/a,p)(defect free) and (a,F/a,p)(defective) > (a,F/a,p)(defect free), is proposed with this observation for identifying the onset of defect-free weld formation. Here F is axial force, tau is torque, and p is welding speed or tool rotation speed or plunge depth. The same criterion is validated with respect to Al 5xxx base material. Even in this case, the axial force and torque remained constant while producing defect-free welds.

System and method of exporting or using welding sequencer data for external systems

Abstract: The invention described herein generally pertains to a system and method for collecting one or more welding parameters in real time during creation of one or more welds using a welding sequence. The one or more welding parameters can be associated with a particular welding sequence. Moreover, based on the one or more welding parameters collected, a modeled welding parameter can be generated to increase quality, efficiency, and the like. A collection component collects real time welding parameter data from which a quality manager component creates a modeled welding parameter. The modeled welding parameter can be employed for the welding sequence to monitor or track the welding parameter during a subsequent weld.

Erratum to: Multi-response optimization using the Taguchi-based grey relational analysis: a case study for dissimilar friction stir butt welding of AA6082-T6/AA5754-H111

Abstract: This paper presents a multi-response optimization process for dissimilar friction stir welding of AA6082/AA5754 aluminum alloys. An L9 orthogonal array was constituted for the experiments. Three welding parameters—tool shoulder diameter-to-pin diameter (D/d) ratio, tool rotational speed (TRS), and welding speed (WS)—were associated with tensile strength and elongation. An optimization process was started to determine the signal-to-noise (S/N) ratio. Grey relational analyses were performed utilizing the S/N ratio. According to the results of a series of analyses, the optimal welding condition was determined as 4 for D/d, 1,000 rpm for TRS, and 100 mm/min for WS. The analysis of variance results showed that all the welding parameters are statistically significant at 95 % confidence level. Additionally, the joint efficiency of welding fabricated at the optimal condition was compared for both AA6082 and AA5754. This revealed that the joint efficiency is 66 % for AA6082 and 92 % for AA5754.

Butt welding of thick, high strength steel plate with a high power laser and hot wire to improve tolerance to gap variance and control weld metal oxygen content

Abstract: This study, which pertains to the butt welding of 590 MPa high strength steel plates with a high power laser over gaps, was conducted to investigate weld penetration characteristics, to clarify welding phenomena, and to develop procedures for obtaining high quality joints. Butt welding was performed on 12 mm thick plates with a 16 kW high power disc laser together with a hot wire. In this way, welding defects are suppressed and weld metal oxygen content is controlled, thereby producing sound, fully penetrated welds. Penetrations were stable over a range of gaps from 0 to 0·4 mm, owing to an ejection of excess melt through a keyhole outlet at the bottom of the molten weld pool by a strong plume. Here, the use of a hot wire together with a laser of sufficient power to produce a fully penetrated keyhole was effective in improving the gap tolerance and suppressing oxygen inclusion within the butt weld.

Investigation and Optimization of Laser Welding of Ti-6Al-4 V Titanium Alloy Plates

Abstract: Titanium alloys are employed for several applications, ranging from aerospace to medicine. In particular, Ti-6Al-4V is the most common, thanks to an excellent combination of low density, high specific strength and corrosion resistance.Laser welding has been increasingly considered as an alternative to traditional techniques to join titanium alloys. An increase in penetration depth and a reduction of possible welding defects is achieved indeed; moreover a smaller grain size in the fused zone is benefited in comparison to either TIG and plasma arc welding, thus providing an increase in the tensile strength of the welded structures.The aim of this work is to develop the regression model for a number of responses which are crucial for the feature of the joint. The study was carried out on 3 mm thick Ti-6Al-4V plates; a square butt welding configuration was considered employing a disk-laser source. A 3-level factorial plan was hence arranged in a face-centred cubic scheme. The responses were analyzed referring to the governing parameters. Then, an optimization was carried out via statistical tools, in order to find the optimal welding set-up for the alloy under examination.Copyright © 2013 by ASME

CO2 laser butt-welding of steel sandwich sheet composites

Abstract: Steel sandwich sheets compared with conventional steel exhibit significant performance improvements such as lower density, higher specific flexural stiffness, and better sound and vibration damping characteristics. However, the main challenge for the broad industrial use is that the joining and assembling methods be used in such a way so as not to alter significantly these characteristics. In the present paper, a laser welding of steel sandwich is examined. The feasibility study of the laser butt-welding of sandwich steel sheets with a CO2 laser beam has revealed that such an approach is possible. A theoretical model of the laser welding process is developed for the investigation of the laser beam impact on both the core and the outer steel layers of the sandwich material. The model presented is based on a novel idea for the simulation of the heat source through the finite element analysis for the estimation of the temperature distribution. Additionally, the effect on the quality of the weld, the strength of the welded sheet, and its damping characteristics are also experimentally investigated and prove that laser welding can be considered as an alternative joining process.

Fatigue strength prediction of ultra high strength steel butt-welded joints

Abstract: First, fatigue tests were performed on butt-welded joints made of novel direct quenched ultra high strength steel with high quality welds. Two different welding processes were used: MAG and Pulsed MAG. The weld profiles, misalignments and residual stresses were measured, and the material properties of the heat-affected zone were determined. Fatigue tests were carried out with constant amplitude tensile loading both for joints in as-welded condition and for joints after ultrasonic peening treatment. Finally, in fatigue strength predictions, the crack initiation phase was estimated using the procedures described by Lawrence et al. [Lawrence F V, Ho N J and Mazumdar P K (1981) Predicting the fatigue resistance of welds. Annu. Rev. Mater. Sci, 11, 401–425]. The propagation phase was simply estimated using S–N curves for normal quality butt welds, which may contain pre-existing cracks or crack-like defects eliminating the crack initiation stage.

Experimental study and modeling of friction stir welding process to produce optimized AA2219 butt welds for aerospace application

Abstract: This article describes the effect of friction stir welding parameters on the mechanical properties and overall macrostructure features of AA2219-T87 welds. The aim is to develop a suitable combinat...

Welding auxiliary joining part and method for connecting components by way of said welding auxiliary joining part

Abstract: A welding auxiliary joining part in the form of a bolt having a head, a shank and a tip is disclosed. The welding auxiliary joining part is driven with the aid of a mechanical thermal setting method into a component made of non-weldable or poorly weldable material. During the driving-in operation, a welding head arises on account of mechanical deformation, such that subsequently the component can be connected via the welding auxiliary joining part to a further component made of weldable material by means of welding.

Effects of grain size and precipitation on liquation cracking of AZ61 magnesium alloy laser welding joints

Abstract: Four kinds of wrought AZ61 alloy sheets with different microstructural features were successfully welded by CO2 laser beam butt welding. Welding joints without visible pores were obtained under optimum process parameters. Effects of grain size and precipitation on liquation cracking behaviours of the laser welding joints were investigated. As far as the as rolled alloy sheets were concerned, liquation in the partially melted zone (PMZ) was visible along grain boundaries, and the extent of liquation was more serious in the alloy sheets with larger grains. As far as the as aged alloy sheets were concerned, plenty of precipitates (β-Mg17Al12) were involved and liquation in the PMZ was found both at grain boundaries and within grains. Moreover, the extent of liquation was more serious in the alloy sheets with more precipitates. It is promising to reduce liquation cracks in the PMZ of magnesium alloys by grain refinement, reducing the size and the quantity of the low melting point phase, and modifying ...

Welding apparatus with automated welding wire retraction

Abstract: A method providing a welding apparatus configured to supply a welding wire to a welding gun and a welding system implementing the same is described. The welding gun has a trigger and an opening where the welding wire extends when the trigger is activated. The method also has a computer with a user interface that includes an automatic wire retract program, the program dynamically adjusting the amount of welding wire retraction based at least upon one of the following: welding arc current, welding wire size, welding wire speed and burnback time. The program monitors the welding gun and determines when the trigger is disabled. The program indicates when a first condition is satisfied and retracts the welding wire so the welding wire preferably does not extend (or minimally extends—or may be at least partially recessed within the tip) from the opening of the welding gun nozzle tip.

Friction Stir Welding on Aluminum Alloy 6063 Pipe

Abstract: In Friction Stir Welding (FSW) process, there is a substantial amount of research done on aluminum plate but very few are found for aluminum pipe due to its tubular shape. A specially customized Orbital Clamping Unit (OCU) was used and fixed on the Bridgeport 2216 CNC milling machine in order to weld an aluminum alloy 6063 pipe butt joint at several welding parameters. This OCU will hold the work pieces together tightly, rotate them at the required constant low speed, and ensure easy removal. This paper will investigate the effect of welding parameters on the tensile strength of joint produced by the FSW process. Several good samples of pipes joint were produced using the present experiment setting.

Finite element simulation of welding residual stresses in martensitic steel pipes

Abstract: Finite element (FE) simulations of the welding of two high grade steel pipes are described. The first is a P91 steel pipe welded with a similar P91 weld consumable, and the second is a P92 steel pipe welded with dissimilar nickel–chromium based weld consumables. Both welds are multipass circumferential butt welds, having 73 weld beads in the P91 pipe and 36 beads in the P92 pipe. Since the pipes and welds are symmetric around their axes, the FE simulations are axisymmetric, allowing high FE mesh refinement and residual stress prediction accuracy. The FE simulations of the welding of the P91 and P92 pipes comprise thermal and sequentially coupled structural analyses. The thermal analyses model the heat evolution produced by the welding arc, determining the temperature history throughout the FE models. Structural analyses use the computed temperature history as input data to predict the residual stress fields throughout the models. Post-weld heat treatment (PWHT) of both pipes has also been numerica...

System and method for determining welding wire diameter

Abstract: A welding system includes a welding wire feeder (20), a welding power supply (16), and a sensor (38). The power supply (16) is coupled to the welding wire feeder (20) and configured to produce a welding arc (12). The sensor (38) is configured to sense a parameter indicative of a size of a welding wire (24) fed through the welding wire feeder. The sensor (38) is configured to send a signal to the power supply (16), the signal representing the parameter indicative of the size of the welding wire (24). The power supply is configured to automatically implement at least one of an arc starting parameter or a welding parameter based on the signal.

Experimental study on mechanical properties and fracture toughness of structural thick plate and its butt weld along thickness and at low temperatures

Abstract: The thick plate induces the variation of mechanical properties and fracture toughness, especially in cold regions. At the low temperature, the brittle behaviour of steel becomes worse. A series of tests (such as uniaxial tensile test and three-point bending test) were carried out at low temperature to investigate the mechanical properties and fracture toughness of structural steel plates of Q345B with thickness of 60 to 150 mm, as well as the fracture toughness of 150 mm thick butt welded plate. The test specimens are all manufactured from plates along thickness with small size, and the tensile test specimens included through-thickness specimens additionally. The ductility index (percentage reduction of area) and the fracture toughness index (critical CTOD values) all decrease with the temperature decreases and the distance from plate surface increases. The results obtained in this paper provide technical basis for preventing brittle fracture of thick plate steel structures in cold regions.