Search results for " aluminum alloy"
showing 10 items of 20 documents
Dissimilar Al/steel Friction stir welding lap joints for automotive applications
2016
A widespread usage of aluminum alloys for the fabrication of car-body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with automotive steel grades. Dissimilar welding of aluminum alloys and steel grades poses some issues concerning the formation of brittle intermetallic compounds, difference in physical and chemical properties of the parent metals, and poor wetting behavior of aluminum. Friction stir welding is considered to be a reasonable solution to obtain sound aluminum/steel joints. A study on the join quality of dissimilar lap joints of steel and aluminum alloy sheets after friction stir welding is proposed here…
Fatigue crack growth in 2024-T351 Friction Stir Welded Joints: longitudinal residual stresses and microstructural effects
2009
Abstract The role of longitudinal residual stress on propagation of fatigue cracks was examined in friction stir welds produced in 2024-T351 aluminum alloy. Fatigue crack growth rate was obtained through constant Δ K Iapp tests for notches at different distances from the weld centerline. Subsequently, crack growth was correlated to weld residual stress measured by the cut-compliance method. It was found that residual stresses correspond to low crack growth rates outside the weld zone during fatigue loading. Once in the weld zone, the crack growth was affected by microstructural and hardness changes. Furthermore, weld residual stresses were mechanically relieved and effects on crack propagat…
Effects of pulse current mode on plasma electrolytic oxidation of 7075 Al in Na2WO4 containing solution: From unipolar to soft-sparking regime
2018
Abstract Plasma electrolytic oxidation coatings were produced on 7075 Al alloy in a silicate based solution containing sodium tungstate using unipolar, usual bipolar and soft-sparking bipolar pulsed current regimes. X-ray diffraction proved that the coatings contain gamma alumina and metallic tungsten. EDS results showed that the tungsten content decreases with increasing the negative half cycle. Scanning electron microscopy showed that the pancake and volcano-like were dominant morphologies for the coatings produced by the unipolar and bipolar current regimes, respectively. Under unipolar current regime, a band of large pores is observed at the metal/coating interface, while they became di…
Numerical investigation on dissimilar Friction Stir Welding of Aluminum and Magnesium sheets
2014
An Innovative Friction Stir Welding Based Technique to Produce Dissimilar Light Alloys to Thermoplastic Matrix Composite Joints
2016
Abstract Aluminum sheets can be joined to composite materials with different techniques. Each of them has advantages and weak points over the others. In literature, new techniques and patents are continuously developed to overcome these difficulties. In the paper a new Friction Stir Welding based approach is proposed to mechanically join AA6082-T6 to self-reinforced polypropylene. The aluminum sheet is pre-holed along both the sides of the weld line. A pinless tool generates the heat and pressure needed to activate back-extrusion of the composite. Joints have been produced with varying hole diameter and pitch. The mechanical resistance of the joint has been evaluated and the different failu…
Design and development of a new machine tool for continuous friction stir extrusion
2023
In the present paper the Continuous Friction Stir Extrusion process (CFSE), derived from the already known Friction Stir Extrusion (FSE), is proposed for effective solid-state recycling of metal scraps. A new dedicated machine tool was designed and developed. A Lagrangian implicit thermomechanical numerical model was set up and used to determine the proper ranges of the most relevant process parameters. An effective case study is proposed, involving the actual extrusion of a recycled wire in a continuous way. Metallurgical observations and mechanical characterization tests were carried out on the obtained specimen showing the potential of the process and its industrial feasibility.(c) 2023 …
RESHAPING AS NOVEL CIRCULAR ECONOMY STRATEGY FOR SHEET METAL BASED END-OF-LIFE COMPONENTS
2022
Making materials consumes about 21% of the global energy demand a specifically metals production, it accounts for about 8% of total global energy consumption. In fact, in the past few decades, the use of lightweight alloys has become increasingly widespread in many major industrial sectors thanks to the weight reduction associated with their applications. Most lightweight materials like aluminum alloys are characterized by high-energy demands primary production cycles that are responsible for a relevant share of the global CO2 emissions. Circular economy strategies such us longer life, more intense use, repair, product upgrades, modularity, remanufacturing, component re-use and open/closed …
A Comparison of Mechanical Properties and Microstructure in Friction Stir Welded and MIG Welded Light Alloys
2012
Joining technologies are in a very interesting phase today due to some relevant innovations concerning new techniques. Friction Stir Welding (FSW) is a relatively new process, patented by TWI in 1991, able to weld through a solid state bonding materials considered difficult to be welded or unweldable by more traditional fusion welding techniques. By using this process welded joints are obtained with no external heat supplier, generating the required temperature increase by means of a revolving pin that follows a proper trajectory partially sunk in the workpiece surface. As for today, although first examples of industrial application can be found in the aeronautical and aerospace fields, the…
Comparative evaluation of the effect of the substrate thickness and inherent process defects on the static and fatigue performance of FSW and adhesiv…
2021
Abstract This work aims at evaluating the mechanical performance of joints in an AA6016 alloy, manufactured by means of two alternative processes: friction stir welding and adhesive bonding. Given its wide use in industrial fields such as automotive and aeronautics, an overlap configuration of joints was selected for the study, and a specific method based on the overlap length evaluation has been developed to allow comparisons among the cases. Two substrate thicknesses are considered in order to vary the overall joint stiffness, and the effect of such geometrical parameter on the mechanical behavior of the joined system is experimentally investigated. The experimental findings highlight tha…
Analytical bonding criteria for joint integrity prediction in friction stir welding of aluminum alloys
2014
Abstract In this study, two bonding criteria, previously used for porthole die extrusion, are applied to FSW starting from the local value of the main field variables calculated through a specifically developed 3D numerical model of the process. Their applicability and effectiveness have been assessed through an experimental and numerical campaign carried out with the main process parameters varying in a wide range. The pressure–time–flow criterion was demonstrated to be better suited for FSW processes when large welding speed is used.