Study and Characterization of EN AW 6181/6082-T6 and EN AC 42100-T6 Aluminum AlloyWelding of Structural Applications: Metal Inert Gas (MIG), Cold Metal Transfer (CMT), and Fiber Laser-MIG Hybrid Comparison

The present research investigates the eects of dierent welding techniques, namely traditional metal inert gas (MIG), cold metal transfer (CMT), and fiber laser-MIG hybrid, on the microstructural and mechanical properties of joints between extruded EN AW 6181/6082-T6 and cast EN AC 42100-T6 aluminum alloys. These types of weld are very interesting for junctions of Al-alloys parts in the transportation field to promote the lightweight of a large scale chassis. The weld joints were characterized through various metallurgical methods including optical microscopy and hardness measurements to assess their microstructure and to individuate the nature of the intermetallics, their morphology, and distribution. The results allowed for the evaluation of the discrepancies between the welding technologies (MIG, CMT, fiber laser) on dierent aluminum alloys that represent an exhaustive range of possible joints of a frame. For this reason, both simple bar samples and real junctions of a prototype frame of a sports car were studied and, compared where possible. The study demonstrated the higher quality of innovative CMT and fiber laser-MIG hybrid welding than traditional MIG and the comparison between casting and extrusion techniques provide some inputs for future developments in the automotive field

Numerical, Mechanical, and Metallurgical Investigation of an Innovative Near Net Shape Titanium Selective Laser Melting Engine Component and Comparison with the Conventional Forged One

Selective laser melting (SLM) can be used to manufacture near net shape (NNS);the main benefits are a remarkable weight reduction, a lower environmentalimpact, the opportunity to integrate some functions, and an improvement of theperformances. The current article covers the development of a Ti6Al4V NNS enginecomponent produced by SLM. Finite element analyses of the main relevantoperating conditions are performed to reach a topological optimization of the part.The main target is weight reduction keeping the same safety performances. Theweight reduction achieved is 45% and 15% with respect to steel and titaniumforging by replacing the original“H”section with an SLM multibranch structure.Other benefits are the manufacturing of the connecting rod (conrod) into twoseparate parts, avoiding the difficult machining to separate the cap from the mainbody and the integration of conformed cooling channels into the conrod. Then, theSLM components are produced and mechanical and metallurgical properties areinvestigated and compared with the titanium hot forging ones. Both the macro-structures present equiassic and isotropic behavior due to the heat treatmenttransformation. No defects are observed for both the technologies. The mechanicalproperties are verified to be aligned with the design targets

A study of a non-conventional evaluation of results from salt spray test of aluminum High Pressure Die Casting alloys for automotive components

Aim of the present work was to investigate in a non-conventional way the results of aluminum castings salt spray tests. These experiments were engineered in order to obtain a quantitative measurement of the corrosion rate, instead of the qualitative visual analysis usually employed in the traditional salt spray test. These tests were performed on aluminum EN AC-46000, EN AC-44400, and EN AC-43500 samples. A comparison was made with electrochemical tests on specimens and the traditional salt spray testing on a real dimension component. The results showed a good reliability of the new method that gave outputs in agreement with the electrochemical technique. The new concept of salt spray test data processing was able to detect very small differences in corrosion behavior of tested alloys, demonstrating higher precision and reliability in respect to the polarization technique. Such result was explained considering the adoption of specimen with larger area and longer time of exposure to the selected corrosive environment that reduce respectively the effect of uneven distribution of porosity and intermetallics in the samples, typical of aluminum castings, and the potential local and transient events related to these defects

Microstructural, Mechanical, and Tribological Evolution under Different Heat Treatment Conditions of Inconel 625 Alloy Fabricated by Selective Laser Melting.

dditive manufacturing (AM) can be particularly advantageous to manufacture components designed to meet challenging structural requirements. Selective laser melting (SLM) microstructure is different than that obtained by traditional manufacturing process; in particular, mechanical and microstructural features achieved herein are influenced by the entire thermal history, including the manufacturing process and the heat treatment (HT) with relevant role of the slow cooling rate adopted. In fact, both the process and the HTs can significantly modify the microstructure and related mechanical and tribological properties. To better understand how mechanical response can be tuned to meet different requirements, in this article the effects of four different vacuum HTs on microstructures, mechanical properties, and wear behavior of Inconel 625 produced with SLM are deeply investigated. In general, the results confirm that HT can significantly change the microstructure and mechanical or tribological properties of Inconel 625. Among the examined HT, solution + aging and direct aging improve the strength of the alloy, whereas annealing leads to recrystallization, reducing strength in favor of ductility. Stress relieving does not significantly change the microstructure and mechanical properties. Considering tribological behavior, only direct aging HT leads to a remarkable improvement, with a reduction in friction coefficient and wear rate

A comparative study of mechanical properties of metal inert gas (MIG)-cold metal transfer (CMT) and fiber laser-MIG hybrid welds for 6005A T6 extruded sheet,

Among the several welding technologies available today, traditional metal inert gas (MIG) one is widely used for junction of Al-alloys parts in transportation field, while cold metal transfer (CMT) and laser techniques are recent alternatives potentially providing advantages over the former one, such as reduction of deformations and reduced alteration of base material. The present research aims to investigate the effects of these different techniques on the microstructural and mechanical (hardness, tensile strength, yield stresses, and elongation) properties of welded joints of 6005A-T6. Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) was used for fractographic observations and to analyze microstructural changes after welding. From this examination, it is found that CMT and fiber laserMIG hybrid joints of AA6005 aluminum alloy showed superior mechanical properties compared with MIG weld

Cradle-to-Gate Impact Assessment of a High-Pressure Die-Casting Safety-Relevant Automotive Component

The mass of automotive components has a direct influence on several aspects of vehicle performance, including both fuel consumption and tailpipe emissions, but the real environmental benefit has to be evaluated considering the entire life of the products with a proper Life Cycle Assessment (LCA). In this context, the present paper analyzes the environmental burden connected to the production of a safety relevant aluminum high pressure die casting component for commercial vehicles (a suspension cross beam) considering all the phases connected to its manufacture. The focus on aluminum high-pressure die casting reflects the current trend of the industry and its high energy consumption. This work shows a new method that deeply analyzes every single step of the component's production through the implementation of a wide database of primary data collected thanks to collaborations of some automotive supplier companies. This energy analysis shows significant environmental benefits of the aluminum recycling

Low Solution Temperature Heat Treatment of AlSi 9 Cu 3 (Fe) High-Pressure Die-Casting Actual Automotive Components

sually, high-pressure die-casting (HPDC) components cannot be heat-treated at high temperature without the occurrence of surface blisters, which are unacceptable for surface finish and may reduce the mechanical properties. In this context, the purpose of the present paper was to analyze the effectiveness of special low solution temperature T6 heat treatment in overcoming this limit for HPDC AlSi 9 Cu 3 alloy. Very low solution temperatures (< 450 °C, followed by 165 °C aging) to prevent the occurrence of blisters were combined with commonly used times (from 1 to 16 h) ensuring the feasibility of industrial application. Treatments were conducted on samples extracted from actual castings to evaluate the typical defects encountered in common production. Properties were analyzed by means of visual inspection, microstructural observations, image analysis, hardness, tensile tests and fractography. The results showed that it is possible to use solubilization temperatures below 450 °C for several hours in a T6 treatment to give strengthening without relevant blistering in AlSi 9 Cu 3 alloy. The optimum match of properties was provided by a solution treatment at 430 °C for 4 h followed by an aging at 165 °C for 8 h, which gave a yield increase of ~ 50 MPa, an increase in ductility and the best Quality Index value

Lightweight of a cross beam for commercial vehicles: Development, testing and validation

Commonly the reduction of weight in transport is applied to passenger cars, while commercial vehicles are still not widely involved due to structural and costs restraints. This research studied a new concept of aluminium cross beam suspension for commercial vehicles that would replace the currently used steel component. The related advantages entail the achievement of an affordable solution, weight reduction of about 50%, environmental benefits, avoidance of painting and excellent recyclability. The use of appropriate materials, a new concept of design and a careful function integration allowed the structural limits to be overcome. The feasibility of this solution was verified through detailed characterisation and testing, composed of an analysis of the most relevant failure modes, with microstructures, hardness tests, tensile tests, fractography, salt spray test and fatigue test bench road simulator with field test data. The validation was successfully completed and the feasibility of the light alloy use for this particular heavy application was demonstrated. Further experiments, based on the development of heat treatments for potential future extension of this application, were conducted with the support of Design Of Experiment methodology. The outputs constitute a useful database of properties

Correlation between Numerical and Experimental Structural Resistance of a Safety Relevant Aluminum Automotive Component

Accurate implementation of weight reduction for the development of innovative safety relevant components, such as suspension assemblies, requires a careful evaluation of the structural resistance. The validation of these critical parts usually employs Finite Element Analysis (FEA) during the design phase and laboratory tests on prototypes during later stages. However, the results of these established methods have rarely been numerically compared. The present paper introduces a method for comparing FEA and testing, based on the elaboration of micro-strains acquired with strain gauges positioned in specific regions. The model was applied to the real case study of an innovative lightweight cross beam. FEA simulations and bench tests under different conditions that were representative of the operating environments were carried out. Two different relevant configurations of fatigue bench tests were considered. Then, the data obtained from testing were numerically elaborated in order to compare them with the analytical results. Real data from in-field measurements were used. The cross beam endured at the elevate mission loads reproduced at the bench test. The FEA and testing results were aligned. The correlation method was proven to be reliable, since it made it possible not only to numerically evaluate the testing output, but also to validate the calculation tools, and it could be extended to similar applications in future

Experimental and numerical study of an automotive component produced with innovative ceramic core in high pressure die casting (HPDC)

Weight reduction and material substitution are increasing trends in the automotive industry. High pressure die casting (HPDC) is the conventional casting technology for the high volume production of light alloys; it has recently found wide application in the manufacturing of critical components, such as complex and thin geometry automotive parts. However, the major restriction of this affordable technology is the difficulty to design and realize hollow sections or components with undercuts. An innovative way to further increase the competitiveness of HPDC is to form complex undercut shaped parts through the use of new lost cores that are able endure the high pressures used in HPDC. This paper investigates the use of innovative ceramic lost cores in the production of a passenger car aluminum crossbeam by HPDC. Firstly, process and structural simulations were performed to improve the crossbeam design and check the technology features. The results led to the selection of the process parameters and the production of some prototypes that were finally characterized. These analyses demonstrate the feasibility of the production of hollow components by HPDC using ceramic cores