Corrosion behavioral studies on AA7075 surface hybrid composites tailored through friction stir processing

2020 ◽  
Vol 67 (4) ◽  
pp. 345-355
Author(s):  
Suganeswaran Kandasamy ◽  
Parameshwaran Rathinasamy ◽  
Nithyavathy Nagarajan ◽  
Karthik Arumugam ◽  
Rajasekar Rathanasamy ◽  
...  

Purpose This paper aims to overcome the corrosion in AA7075 by incorporating the dual-reinforcements like Al2O3 and SiC through friction stir processing (FSP). In recent days, an automotive monocoque structure undergoes corrosion because of changes in environmental conditions. Design/methodology/approach Surface hybrid composites (SHCs) of AA7075 with different weight ratios of Al2O3 and SiC were fabricated at a rotating speed of 1000 rpm, traveling speed of 56 mm/min and tool tilt angle of 2º with two passes. Surface regions were observed using optical microscopy, and the potentiodynamic corrosion test was performed under a 3.5 per cent NaCl environment at room temperature. Then, the surface morphology analysis of corroded samples and their structural properties were also investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS). Findings Through FSP, an improved interface between the reinforced particles and the AA7075 base matrix was observed because of the severe plastic deformation. Potentiodynamic polarization tests confirmed that the AA7075 matrix with a higher concentration of Al2O3 and a lower concentration of SiC (Al2O3 – 75 per cent and SiC – 25 per cent) possesses a lower corrosion rate than other specimens. This result is because of the combined effect of stable passive film formation and the resistance produced by hard SiC particles. In addition, the formation of a stronger interface between the reinforcements and the base matrix impedes the NaCl solution attack. The SEM micrograph depicts the film crystallinity variations with an increase in Al2O3 content. Debonding between the layers was observed on increasing the SiC content in the base matrix. XRD shows the peaks of reinforcing elements that influence the corrosion behavior. These observations suggest that the AA7075 reinforced with a higher concentration of Al2O3 and a lower concentration of SiC through FSP affords a suitable solution for automotive monocoque applications. Originality/value The corrosion rate has been identified for AA7075 SHCs with various concentrations of Al2O3 and SiC and has been compared with that of the base metal and the friction stir processed specimen without reinforcement.

2019 ◽  
Vol 8 (5) ◽  
pp. 3733-3740 ◽  
Author(s):  
Namrata Gangil ◽  
Sachin Maheshwari ◽  
Arshad Noor Siddiquee ◽  
Mustufa Haider Abidi ◽  
Mohammed A. El-Meligy ◽  
...  

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ch. Mohana Rao ◽  
K. Mallikarjuna Rao

PurposeThe objective of the paper is to evaluate the fabrication process and to study the influence of process parameters of friction stir processing of 6061-TiB2-Al2O3 Aluminum alloy surface composite on microhardness tensile strength, and microstructure.Design/methodology/approachFriction stir processing method is used for attaining the desired mechanical properties, and selectively processed reinforcements to fabricate the samples. The Taguchi technique was used to optimize rotational speed, travel speed and volume percentage of reinforcement particles to enhance the mechanical properties of 6061-TiB2-Al2O3 Aluminum alloy composite.FindingsThe fabrication of surface composites through FSP allows new inventions in terms of material with enhanced surface layers without changing the base metal.Practical implicationsTo examine the behavior of the surface of the composites in the different zones, the practical implication consists of the use of different characterization techniques like optical microscopy and scanning microscopy for microstructural behavior and the measurement of hardness and tensile tests for mechanical behavior.Originality/valueThe research work consists of tool design and process parameters, which can affect the final product (microstructural changes), and the performance of the modified surface layer behavior was studied and presented.


Author(s):  
Murahari Kolli ◽  
Devaraj Aruri ◽  
Kumar Adepu

Aluminum based hybrid composites are advanced materials having the properties of high hardness, superior wear resistance, strength, high elevated temperature and low thermal expansion coefficient. These hybrid composites are widely used in industries like automobile and aerospace. In this present paper 6061-T6 Aluminum alloy reinforced with SiC and Gr particles, hybrid composites are fabricated by using Friction stir processing (FSP) technique. It prevents the further development of hybrid composites for machining by nonconventional methods like water jet and laser cutting process. Electrical discharge machining (EDM) is used for machining the complex shapes of the material. This paper presents an overview of EDM studies conducted on the Al-SiC/Gr hybrid composites using a copper electrode in EDM. The EDM experiment machining parameters such as the dielectric fluid, peak current, pulse on, pulse off times are changed to explore their effects on machining performance, material removal rate (MRR), Tool wear rate (TWR), and surface roughness (SR). It is observed that the MRR and SR of the Al-SiC/Gr hybrid composites increase with an increase in the current.


Author(s):  
A. Kumar ◽  
A. Devaraju ◽  
B. Kotiveerachari

In this investigation, the influence of tool rotational speed on wear and mechanical properties of Aluminum alloy based surface hybrid composites fabricated via Friction stir processing (FSP) was studied. The fabricated surface hybrid composites have been examined by optical microscope for dispersion of reinforcement particles. Microstructures of all the surface hybrid composites revealed that the reinforcement particles (SiC, Gr and Al2O3) are uniformly dispersed in the nugget zone. It is observed that the microhardness is decreased with increasing the rotational speed and exhibited higher microhardness value in Al-SiC/Al2O3 surface hybrid composite at a rotational speed of 900 rpm, due to presence and pining effect of hard SiC and Al2O3 particles. It is also observed that high wear resistance exhibited in the Al-SiC/Gr surface hybrid composites at a rotational speed of 900 rpm due to presence of SiC and Gr acted as load bearing elements and solid lubricant respectively. The observed wear and mechanical properties have been correlated with microstructures and worn morphology.


2019 ◽  
Vol 18 (3) ◽  
pp. 653-687 ◽  
Author(s):  
Bhavya Swathi I. ◽  
Suvarna Raju L. ◽  
Perumalla Janaki Ramulu

Purpose Friction stir processing (FSP) is overviewed with the process variables, along with the thermal aspect of different metals. Design/methodology/approach With its inbuilt advantages, FSP is used to reduce the failure in the structural integrity of the body panels of automobiles, airplanes and lashing rails. FSP has excellent process ability and surface treatability with good corrosion resistance and high strength at elevated temperatures. Process parameters such as rotation speed of the tool, traverse speed, tool tilt angle, groove design, volume fraction and increase in number of tool passes should be considered for generating a processed and defect-free surface of the workpiece. Findings FSP process is used for modifying the surface by reinforcement of composites to improve the mechanical properties and results in the ultrafine grain refinement of microstructure. FSP uses the frictional heat and mechanical deformation for achieving the maximum performance using the low-cost tool; the production time is also very less. Originality/value 100


Author(s):  
Mostafa Akbari ◽  
Mohammad Hasan Shojaeefard ◽  
Parviz Asadi ◽  
Abolfazl Khalkhali

Aluminum-base surface hybrid composites have been fabricated by mixtures of SiO2 and Al2O3 particles on an Al–Si cast aluminum alloy using friction stir processing with the aim of achieving higher wear properties in the Al piston alloy via surface hybrid composites fabrication. The distribution of particles in the stir zone was evaluated via scanning electron microscope. Microstructures of the composites revealed that the reinforcing particles were uniformly distributed in the stir zone. Furthermore, the mechanical properties of each composite were determined using hardness tests indicating that increase in the relative content of SiO2 resulting in a decrease in the average hardness of the stir zone. Additionally, the wear resistance of the surface hybrid composites was investigated under normal load, sliding speed, and distances of 20 N, 1 m/s, and 4000 m, respectively. It was found that the wear mass loss of the 20% SiO2–80% Al2O3 hybrid composites (which was about 4.2 mg) was improved when compared with that of the A356 base alloy (nearly 19 mg). Moreover, by increasing the relative content of SiO2 particles from 0% to 100% in the hybrid composites, the friction coefficient of the composites rose from 0.55 to 0.73. It can be concluded by adding Al2O3 and SiO2 particles in the Al matrix, wear mass loss can be decreased by about five times compared with that of the base metal, in which the Al2O3 particle increases the hardness and SiO2 particles acts as lubricating agent, and the combination of these leads to better wear properties. The best combination of the hybrid particles in order to achieve the best wear properties for the hybrid composites is 20% Al2O3 and 80% SiO2.


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