Effect of Flow-Forming Processes on Microstructure and Grain Size of AA 6061 Aluminium Alloy

In this paper, the micro-groove structure is designed on the surface of aluminum alloy by high speed wire cutting discharge machine (HS-WEDM). A multi-scale surface with micro structure was fabricated by this method. The paper design a series different groove spacing, groove depth and groove width and orthogonal design was using to analyze the relationship between the size of micro structure and the wettability of materials. The results show that the effect of the groove width on surface wettability is maximum, When the the groove spacing is 300μm, the groove depth is 100μm and the width of the groove is 230μm, the contact angle of the material surface is maximum, which is 155.98°. After observing the surface, it is can be known that the existence of groove structure can reduce the droplet and solid surface contact area greatly. In addition, these grooves sealed a plenty of air to increase the contact area of the droplet and the air that the solid surface are difficult to be wetted by droplets. It is feasible that realizing the change of the surface wettability by using optical combination.

Role of nanostructure in pitting of Al–Cu–Mg alloys

Through process Modeling applied to the fatigue design of cast A356-T6 components

Naked eye observations of microstructurally short fatigue cracks

The aim of this work is to determine the effect of manufacturing conditions, especially milling time, on the microstructure and crystallite size of a newly developed nanostructural composite material with the aluminium alloy matrix reinforced with halloysite nanotubes. Halloysite, being a clayey mineral of volcanic origin, is characterized by high porosity and large specific surface area. Thus it can be used as an alternative reinforcement in metal matrix composite materials. In order to obtain this goal, composite powders with fine microstructures were fabricated using high-energy mechanical alloying, cold compacting and hot extrusion techniques. The obtained composite powders of aluminium alloy reinforced with 5, 10 and 15 wt% of halloysite nanotubes were characterized with SEM, TEM and XRD analysis. It has been proven that the use of mechanical alloying leads to a high degree of deformation, which, coupled with a decreased grain size below 100 nm and the dispersion of the refined reinforcing particles–reinforces the material very well.

The paper considers the use of a hybrid technological complex combining volumetric electric arc surfacing and surface thermal hardening with a non-melting electrode in order to improve the performance characteristics of the AК5 aluminum alloy. The features of this method are analyzed in comparison with traditional technologies of surface hardening and restoration, including laser surfacing, plasma spraying and chemical-thermal treatment. It is shown that using a combined approach makes it possible to form a more dense and homogeneous structure of the deposited layer, increasing its adhesion, strength, wear resistance and corrosion resistance. The effect of high-speed heat dissipation and the balance of arc polarity from a non-melting electrode on changes in the microstructure and grain sizes of thе phase and eutectic of the AК5 alloy deposited using WAAM technology is shown. The results of the study demonstrate the prospects of this approach for increasing the durability and operational reliability of AК5 aluminum alloy products in various industries. The prospects of using this hybrid technology to improve the structure and properties of aluminum alloy products obtained using WAAM technology are noted.

In this project the effect of dry ice cooling on grain size and influence of microstructure on mechanical properties of Friction stir welding of Aluminium AA2014 has been investigated. Friction stir tool is the key art of friction stir welding process. For this purpose, different stir pins like square pin and taper pin with screw thread were used to carry out a welding process. Vickers hardness is used to measure the micro hardness in various zones of welded joints. It is observed that the grain size is decreased under friction stir welding due to rapid cooling with dry ice as a coolant by using an optical microscope and mechanical properties are enormously improved and these properties have been correlated with microstructures.

The aluminum-magnesium-silicon alloy 6201-T81 is a popular electrical conductor, widely used for overhead and distribution lines. Its light weight makes its mass conductivity twice that of copper. Aluminum conductors however experience creep, corrosion, power loss, and other drawbacks. Therefore, it has become a necessity for manufacturers to improve mechanical and electrical properties. The alloy 6201-T81 is an age hardenable alloy, in which a controlled precipitation of Mg2Si is performed through two different successive heat treatments: Solution heat treatment and precipitation heat treatment. ∅ 3.5 mm wires of the alloy were solution heat treated at 510 °C for an hour, quenched in ice water, and precipitation heat treated at the temperature range 150–200°C for the time range 2–24 h. Results show that strength and hardness increase with aging time at the precipitation heat treatment temperatures 150 °C, 165 °C, and 175 °C, but decreased with aging time at 185 °C and 200 °C. The increase was due to the precipitation of finely and uniformly coherent needle-like Mg2Si precipitates, β″. The decrease was due to the precipitation of the semi-coherent and incoherent rod-like Mg2Si precipitates β′ and β, respectively. Electrical conductivity increases with the aging temperature and time. Maximum conductivity was 60 %IACS obtained after treatments (185°C, 18h), (200 °C, 13h), and (200 °C, 24h. Optimum mechanical properties were obtained after the treatment (165 °C, 18 h) (313 MPa, 8%, 95 HV, and 57.7 %IACS). Optical micrographs verified the correlation between the microstructural grain size and both the mechanical and electrical properties.

The magnesium silicide precipitates in the 6XXX series alloy are the main components contributing to the heat treatable properties and T6 strength of the alloy, which is influenced by the size, morphology and distribution of this phase. During the extrusion process, the strength contributing phase, magnesium silicide is supposed to dissolve and form again in a controlled state during age hardening. Whereas the intermetallic AlFeSi phase has little if any influence on the strength, the β phase of this intermetallic is known to cause brittle fracture of this alloy, as opposed to the less detrimental, more equiaxed α phase formed during homogenisation.This study investigates the as-extruded 6060 and the more heavily alloyed 6261 aluminium alloys, as well as the subsequent heat treated forms to investigate the ageing conditions to optimise hardening and shorten age hardening times for higher cost effectiveness. The microstructure, texture and precipitate size and distributions were studied using optical microscopy, SEM, EBSD and DSC. SEM and EDAX results have indicated signs of evenly distributed α AlFeSi and β Magnesium Silicide precipitates. The phase responsible for hardening is believed to be the much smaller scaled β" magnesium silicide, requiring much higher resolution studies.