scholarly journals The Effect of Solid-State Processes and Heat Treatment on the Properties of AA7075 Aluminum Waste Recycling Nanocomposite

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6667
Author(s):  
Huda Mohammed Sabbar ◽  
Zulkiflle Leman ◽  
Shazarel Shamsudin ◽  
Suraya Mohd Tahir ◽  
Che Nor Aiza Jaafar ◽  
...  

Direct solid-states, such as hot extrusion and equal channel angular pressing (ECAP), are alternative and efficient solid-state processes for use in recycling aluminium scrap. These processes utilise less energy and are eco-friendly. Ceramic particles such as ZrO2 are suggested as alternatives in the production of metal composites. This study investigated and optimised the effects of various parameters of reinforced ZrO2 nanoparticles on the mechanical and physical properties via response surface methodology (RSM). These parameters were the volume fraction (VF), preheating temperature (T), and preheating time (t). The effects of these parameters were examined before and after the heat treatment condition and ECAP. Each parameter was evaluated at varying magnitudes, i.e., 450, 500, and 550 °C for T, 1, 2, and 3 h for t, and 1, 3, and 5% for VF. The effect that process variables had on responses was elucidated using the factorial design with centre point analysis. T and VF were crucial for attaining the optimum ultimate tensile strength (UTS) and microhardness. Reducing VF increased the mechanical properties to 1 vol% of oxide. The maximum hardness of 95 HV was attained at 550 °C, 1.6 h, and 1 vol% ZrO2 with a density of 2.85 g/cm3 and tensile strength of 487 MPa. UTS, density, and microhardness were enhanced by 14%, 1%, and 9.5%, respectively. Additionally, the hot extrusion parameters and ECAP followed by heat treatment strengthened the microhardness by 64% and density by 3%. Compression pressure and extrusion stress produced in these stages were sufficient to eliminate voids that increased the mechanical properties.

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.


Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 608
Author(s):  
Anastasiya Toenjes ◽  
Heike Sonnenberg ◽  
Axel von Hehl

The mechanical properties of heat-treatable aluminium alloys are improved and adjusted by three different heat treatment steps, which include solution annealing, quenching, and aging. Due to metal-physical correlations, variations in heat treatment temperatures and times lead to different microstructural conditions with differences in the size and number of phases and their volume fraction in the microstructure. In this work, the investigations of the correlation between microhardness measurements on micro samples and the conventional mechanical properties (hardness, yield strength and tensile strength) of macro samples and the comparability of the different heat treatment states of micro and macro samples made of a hardenable aluminium alloy EN AW-6082 will be discussed. Using the correlations between the mechanical properties of micro samples and macro samples, the size of the samples and, thus, the testing cost and effort can be reduced.


2013 ◽  
Vol 747-748 ◽  
pp. 390-397 ◽  
Author(s):  
Ji Lin Li ◽  
Yue Qun Ma ◽  
Rong Shi Chen ◽  
Wei Ke

The distribution of shrinkage porosities in sand cast Mg-Y-RE (WE54) alloy castings was characterized through density measurement and calculated by Archimedess principle. The effect of porosity on mechanical properties of sand cast WE54 alloy was investigated through tensile tests and microstructure observation. It was found that the shrinkage porosities distributed mainly in the middle of the plate where the liquid feeding was quite inconvenient. And the porosities were formed along grain boundaries when secondary phases formed at the end of solidification. Hardness tests showed that the vikers hardness declined linearly with increasing porosity volume fraction. While the tensile strength and nominal yield strength declined exponentially as the porosity volume fraction increased. Microstructure observation showed that the fracture cracks propagated along the grain boundaries where porosities and secondary phases gathering together in as-cast WE54 alloy. The tiny porosities distributed in the secondary phases were observed, which could reduce the tensile strength of cast specimens significantly. The heat treatment strengthening effects were significantly weakened by porosities, and even no heat treatment strengthening effect was detected when the porosity volume fraction was higher than 1%. The microstructure observation also proved that no heat treatment strengthening effect existed in samples containing porosities.


2010 ◽  
Vol 638-642 ◽  
pp. 3313-3318 ◽  
Author(s):  
Sung Joon Kim

The mechanical properties and microstructures of alternative low carbon TRIP-aided steels in which manganese contents mediate between conventional low-alloyed TRIP-aided steels and TWIP steel have been investigated. A variety of microstructures, from a single austenite phase to multiple phase mixtures, was attained according to chemical compositions as well as heat treatment schedule. By means of reverse transformation of martensite combined with controlled annealing, a remarkable grain refinement being responsible for stabilization of austenite could be achieved. In case of the duplex (+ ) microstructures in 6Mn and 7Mn alloys, large amount of retained austenite more than 30 % contributed to substantial improvement of ductility compared to the conventional TRIP-aided steels having similar tensile strength level. In nearly single austenitic 13Mn alloy, the annealed sheet steel exhibited high tensile strength of 1.3 GPa with sufficient ductility due to the stain induced martensite transformation of fine grained austenite.


2019 ◽  
Vol 961 ◽  
pp. 80-87
Author(s):  
Mohammad Hussein Rady ◽  
Ahmed Sahib Mahdi ◽  
Mohammad Sukri Mustapa ◽  
Shazarel Shamsudin ◽  
Mohd Amri Lajis ◽  
...  

Products by solid-state recycling of aluminum chips in hot extrusion process were controlled by temperature related parameters using preheating temperature 450 °C, 500 °C, and 550 °C for 1 hr, 2 hr, and 3 hr preheating time. By using Design of Experiments (DOE), the results found that the preheating temperature is more important to be controlled rather than the preheating time and increasing of temperature led to the high tensile strength. The profile extruded at 550 °C with 3 hr duration had gained the optimum case to get the maximum tensile strength. For the optimum case, heat treatment was carried out using quenching temperature at 530 oC for 2 h and aging process at 175 oC for 4 h. The tensile strength of extrudes specimen was improved significantly compared to those of non-treated specimen.


2017 ◽  
Vol 730 ◽  
pp. 317-320 ◽  
Author(s):  
Syaiful Nizam Ab Rahim ◽  
Mohd Amri Lajis

In this research, mechanical properties of recycled 6061 aluminium alloy, produced by solid state recycling through extrusion, were compared to as-received billets. Aluminum 6061 chips were extruded using a hot extrusion machine. The effects of extrusion parameters on the mechanical properties of the produced recycled 6061 aluminium alloy were investigated. The objective of the study was to analyze the mechanical and structural features of the alloy after plastic consolidation. The extrusion processes were conducted at different preheat temperatures and preheat times, while the ram speed was kept constant. The findings of the study highlighted the potential of combining the extrusion process parameters as an efficient processing route for production of high quality and high-performance type of extruded billets. Tensile test results showed that, material extruded at 550°C exhibited better mechanical properties compared to that extruded at 400°C. The higher temperature resulted in a higher tensile strength being produced, at the expense of a trade-off in ductility. Overall, it was revealed that, the ultimate tensile strength (UTS) and elongation (ETF) of the produced recycled 6061 aluminium through extrusion exhibited mechanical and structural properties comparable to those of the as-received billets.


Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 664 ◽  
Author(s):  
Sandra Kernebeck ◽  
Sebastian Weber

Aluminum profiles—for instance, profiles made of precipitation-hardenable alloys—are increasingly used for decorative details in the automotive industry. Typically, after hot extrusion and at least two to three days of natural aging (NA), the aluminum profiles are artificially aged. A commercial EN AW-6060 alloy of high purity was used for this investigation. Tensile tests were used as the main measurement method. This article focuses on the effect of short-term heat treatment on the point in time at which a significant increase of the ultimate tensile strength (UTS) during NA can be measured. Short-term heat treatment is shown to delay this point in time by almost four days, but it increases the variation of UTS. A heterogeneous temperature profile during short-term heat treatment was identified as one reason for this result. Finally, a strategy for minimizing variations in mechanical properties of artificially-aged aluminum alloys was developed, based on the experimental results of this study.


Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2795 ◽  
Author(s):  
Alireza Vahedi Nemani ◽  
Mahya Ghaffari ◽  
Ali Nasiri

Wire arc additive manufacturing (WAAM) is known to induce a considerable microstructural inhomogeneity and anisotropy in mechanical properties, which can potentially be minimized by adopting appropriate post-printing heat treatment. In this paper, the effects of two heat treatment cycles, including hardening and normalizing on the microstructure and mechanical properties of a WAAM-fabricated low-carbon low-alloy steel (ER70S-6) are studied. The microstructure in the melt pools of the as-printed sample was found to contain a low volume fraction of lamellar pearlite formed along the grain boundaries of polygonal ferrite as the predominant micro-constituents. The grain coarsening in the heat affected zone (HAZ) was also detected at the periphery of each melt pool boundary, leading to a noticeable microstructural inhomogeneity in the as-fabricated sample. In order to modify the nonuniformity of the microstructure, a normalizing treatment was employed to promote a homogenous microstructure with uniform grain size throughout the melt pools and HAZs. Differently, the hardening treatment contributed to the formation of two non-equilibrium micro-constituents, i.e., acicular ferrite and bainite, primarily adjacent to the lamellar pearlite phase. The results of microhardness testing revealed that the normalizing treatment slightly decreases the microhardness of the sample; however, the formation of non-equilibrium phases during hardening process significantly increased the microhardness of the component. Tensile testing of the as-printed part in the building and deposition directions revealed an anisotropic ductility. Although normalizing treatment did not contribute to the tensile strength improvement of the component, it suppressed the observed anisotropy in ductility. On the contrary, the hardening treatment raised the tensile strength, but further intensified the anisotropic behavior of the component.


2011 ◽  
Vol 471-472 ◽  
pp. 1171-1176 ◽  
Author(s):  
A. Bahrami ◽  
A. Razaghian ◽  
M. Emamy ◽  
H.R. Jafari Nodooshan ◽  
G.S. Mousavi

In this study, the relationship between microstructures and mechanical properties of the extrusion processed Al-15wt.%Mg2Si composite was investigated after applying various extrusion ratios (6:1, 12:1 and 18:1) and solution treatment. Various techniques including metallography, tensile testing and SEM fractography were utilized to characterize the mechanical behavior of the MMC. Results demonstrated that extruded and heat treated composite possesses considerably higher strength and enhanced ductility in comparison with the as-cast samples. It was also found that heat treatment and extrusion processes do not change the primary Mg2Si morphology considerably, but its size increases as extrusion ratio decreased. Heat treatment and extrusion ratio effects on tensile strength, elongation of extruded specimens were also studied in this work.


Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1556
Author(s):  
Zhao Li ◽  
Run Wu ◽  
Mingwei Li ◽  
Song-Sheng Zeng ◽  
Yu Wang ◽  
...  

High boron steel is prone to brittle failure due to the boride distributed in it with net-like or fishbone morphology, which limit its applications. The Quenching and Partitioning (Q&P) heat treatment is a promising process to produce martensitic steel with excellent mechanical properties, especially high toughness by increasing the volume fraction of retained austensite (RA) in the martensitic matrix. In this work, the Q&P heat treatment is used to improve the inherent defect of insufficient toughness of high boron steel, and the effect mechanism of this process on microstructure transformation and the change of mechanical properties of the steel has also been investigated. The high boron steel as-casted is composed of martensite, retained austensite (RA) and eutectic borides. A proper quenching and partitioning heat treatment leads to a significant change of the microstructure and mechanical properties of the steel. The net-like and fishbone-like boride is partially broken and spheroidized. The volume fraction of RA increases from 10% in the as-cast condition to 19%, and its morphology also changes from blocky to film-like. Although the macro-hardness has slightly reduced, the toughness is significantly increased up to 7.5 J·cm−2, and the wear resistance is also improved.


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