Saeed Farahany | Buein Zahra Technical University (original) (raw)

Papers by Saeed Farahany

Materials Science Forum, Jun 1, 2015

In the article the chosen problems connected with corrosion of the maritime construction material... more In the article the chosen problems connected with corrosion of the maritime construction materials with particular consideration of the passive anticorrosion protection using high strength aluminum alloy and its welded joints were presented. Also currently used methods of anticorrosion protection of maritime constructions with use of aluminium and its alloys in form of protective coatings and sacrifi cial anodes were described. The fi rst part of the article presents the corrosion resistance of the basic material of the tested alloys series 7xxx (Al-Zn-Mg alloys). In the further part of the article the results of the own researches concerning the passive protection of the Al-Zn-Mg alloy and its joints of the AlZn5Mg2CrZr alloy (mark 7020M) with the systems of protective paints and sacrifi cial anode cathodic protection were presented. 7020M alloy is a modifi cation of the chemical composition of the alloy 7020 (AlZn4,5Mg1 alloy). In the 7020M alloy the increase of corrosion resistance and strength was obtained by increasing the total Zn+Mg>7% and adding Cr and Zr. The eff ectiveness of the anticorrosion protection has been determined by a comparison of the mechanical properties deterioration of the protected and unprotected welded joints that were set under the infl uence of stress and artifi cial seawater. The welding process is a type of heat treatment consisting of: heating, supersaturation and cooling at room temperature. This type of heat treatment called natural is the most susceptible to corrosion in seawater. Each type of welded joint means increased corrosion susceptibility. The system of epoxy paints provides more effi cient protection from the eff ects of stress corrosion for the welded joints of 7020M alloy than the system of polyvinyl paints. Electrochemical potential of 7020M alloy determined on microstructure depends on chemical composition and heat treatment. This group of materials, which are characterized by the electrochemical potential lower than-1000mV vs. SCE, can be used in sacrifi cial anodes for the tested alloy. Sažetak U radu se prikazuju izdvojeni problemi koji se tiču korozije materijala u brodskim konstrukcijama, s posebnim osvrtom na pasivnu zaštitu od korozije uporabom visokootpornih legura aluminija i zavarenih spojeva. Također se opisuju metode zaštite od korozije koje se trenutno koriste uporabom aluminija i njegovih legura u obliku zaštitnih premaza i trošenja anoda. U prvome dijelu rada opisuje se otpornost osnovnih materijala testiranih serija legura 7xxx (legure Al-Zn-Mg) na koroziju. U nastavku rada izlažu se rezultati autorova istraživanja pasivne zaštite legure Al-Zn-Mg i spojeva legure AlZn5Mg2CrZr (oznaka 7020M) sustavima zaštitnih boja i katodne zaštite trošenjem anode. Legura 7020M predstavlja modifi kaciju kemijskog sastava legure 7020 (AlZn4,5Mg1 legure). U leguri 7020M povećanje otpornosti na koroziju i čvrstoća materijala postignuti su povećanjem ukupnog Zn+Mg>7% i dodavanjem Cr i Zr. Učinkovitost zaštite od korozije utvrđuje se usporedbom mehaničkih svojstava propadanja zaštićenih i nezaštićenih zavarenih spojeva koji su izloženi naprezanju i imitaciji morske vode. Postupak zavarivanja vrsta je toplinske obrade koja se sastoji od: zagrijavanja, supersaturacije i hlađenja na sobnoj temperaturi. Ovaj tip toplinske obrade, koji se naziva prirodnim, najosjetljiviji je na koroziju u morskoj vodi. Svaka vrsta zavarenog spoja znači veću izloženost koroziji. Sustav epoksi boja pruža učinkovitiju zaštitu od učinaka korozije pri naprezanju zavarenih spojeva legure 7020M nego sustav polivinil boja. Elektrokemijski potencijal mikrostrukture legure 7020M ovisi o kemijskom sastavu i toplinskoj obradi. Ova skupina materijala, koje karakterizira elektrokemijski potencijal niži od-1000mV nasuprot SCE, može se koristiti u trošenju anode za testiranu leguru. KEY WORDS aluminium alloy welded joints sacrifi cial anode cathodic protection coatings KLJUČNE RIJEČI legura aluminija zavareni spojevi katodna zaštita trošenjem anode premazi

International Journal of Metalcasting, Apr 4, 2023

Journal of Alloys and Compounds, May 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Applied Mechanics and Materials, Oct 1, 2011

Journal of Materials Engineering and Performance, Mar 21, 2017

Effects of TiB 2 addition on microstructure and mechanical properties of Ti-48Al-2Cr-2Nbþ (0.72,1... more Effects of TiB 2 addition on microstructure and mechanical properties of Ti-48Al-2Cr-2Nbþ (0.72,1.62) wt% TiB 2 alloys fabricated by the induction skull melting (ISM) process were investigated. Results showed that the TiB 2-induced microstructure was characterized by randomly orientated fully lamellar colonies and both the colony size and lamellae spacing were refined (100 μm and $ 185 nm, respectively) by TiB 2 addition. The borides were identified to be TiB 2 with plate, needle and block morphologies, determined by different growth stages during solidification. At room temperature and 700°C, the TiB 2-containing alloys exhibit non-deteriorated fracture toughness and superior tensile properties than that of the as-cast and heat-treated matrix alloys. Furthermore, the fracture toughness anisotropy was eliminated due to the randomly orientated lamellar microstructure induced by TiB 2 addition. The fine TiB 2 particles with special morphology (plate and needle) and the easy-to-deform ligament bridges induced by the refined microstructure can account for the notable fracture toughness of the studied TiB 2-containing alloys. The main toughening mechanism was analyzed and discussed in light of the microstructure characterization, size and morphology of borides and the deformed ligament bridges.

Transactions of Nonferrous Metals Society of China, 2016

Abstract The microstructure evolution, mechanical and corrosion properties of Al–11Si–2Cu–0.8Zn d... more Abstract The microstructure evolution, mechanical and corrosion properties of Al–11Si–2Cu–0.8Zn die cast alloy treated with Bi, Sb and Sr additions were investigated. The results of mechanical testing showed that all additions increased impact toughness, ultimate tensile strength, and elongation of the alloy as a result of change in eutectic Si morphology. The analysis of fracture surfaces revealed that with addition of Sr and to lesser extent Bi and Sb, the alloy exhibited a predominantly ductile fracture rather than quasi-cleavage brittle fracture. Moreover, with the additions of Sr, Bi and Sb, the quality index increased to 164.7 MPa, 156.3 MPa and 152.6 MPa respectively from 102 MPa for the base alloy. Polarization corrosion tests conducted in sodium chloride solution showed that the corrosion potential shifted to more negative values with additions of Sb, Bi and Sr, respectively. Corrosion immersion tests also revealed that the element additions have a detrimental effect on the corrosion rate of alloys, due to the increase of boundaries between the Al and eutectic Si phases.

Journal of Materials Science & Technology, Nov 1, 2016

This work investigated the microstructure evolution, tensile, impact, hardness, and sliding wear ... more This work investigated the microstructure evolution, tensile, impact, hardness, and sliding wear properties of an Al–20Mg2Si–2Cu in situ composite treated with different Bi contents. The desired modification of primary Mg2Si particles was achieved with the addition of 0.4 wt% Bi. Increasing Bi beyond 0.4 wt% resulted in a loss of modification, possibly due to the formation of Al8MgBiSi4 compound before the precipitation of the primary Mg2Si. Additionally, the structure of the pseudo-eutectic Mg2Si was transformed from plate to fibrous, which was consistent with decrease of growth temperature extracted from the cooling curve thermal analysis. Addition of Bi had an effect on the morphology of Al5FeSi (β), Al2Cu (θ) and Al5Cu2Mg8Si6 (Q) intermetallic compounds. The tensile strength, elongation percentage, impact toughness, and hardness increased by 6%, 13%, 75%, and 23%, respectively, due to modification of both the primary and eutectic Mg2Si crystals. The tensile and impact fracture surfaces showed fewer decohered particles in the Bi-treated composite. The enhancement in wear resistance of the Bi-treated composite could be attributed to solid lubricant function of insoluble soft Bi phase and modification effects on Mg2Si particles.

Recognizing the importance of upcoming newage business practices and the changes technology has b... more Recognizing the importance of upcoming newage business practices and the changes technology has brought about in the way organizations function, and attempts at being a platform for fostering discussion on contemporary issues.

Four binary cast Mg-Ga alloys containing 1, 2, 3 and 4 wt.% Ga were studied in terms of microstru... more Four binary cast Mg-Ga alloys containing 1, 2, 3 and 4 wt.% Ga were studied in terms of microstructure and degradation behavior. The alloys present two types of intermetallics: (i) the second phase Mg 5 Ga 2, which volume increases with the amount of Ga in the alloy, and (ii) inclusions containing impurities. For the first time, the binary Mg-Ga system is analyzed paying particular attention to the effect of secondary phases (Mg 5 Ga 2) and impurities on the localized corrosion mechanism using AFM/ SKPFM. Inclusions containing impurities reveal a high Volta potential difference, enough to form an active galvanic couple. However, localized electrochemical activities decrease with time leading to uniform degradation. For short immersion times, there is no clear influence of the element Ga on the corrosion behavior, measured by electrochemical and hydrogen evolution tests. However, for longer immersion times, increasing the amount of Ga in the alloy shows a clear negative effect. Electrochemical measurements reveal that higher Ga containing alloys form faster an oxide layer which is not stable.

Journal of Materials Science & Technology, 2016

Advanced Materials Research, Oct 1, 2015

Dry sliding wear and friction behavior of cast A356 Al-Si alloy and composite containing 5wt. % Z... more Dry sliding wear and friction behavior of cast A356 Al-Si alloy and composite containing 5wt. % ZrO2 particles were studied by means of a pins-on-disk apparatus over loads of 5N, 20N and a sliding speed of 0.628m/s. The experimental results showed that the composites exhibited a higher wear resistance in comparison to that of the unreinforced A356 alloy. The friction coefficient of tested materials increased with increasing applied load from 5 to 20 N. FESEM investigations revealed that the wear mechanism of the A356 matrix alloy changed from sever abrasive, adhesive wear into mild abrasion and adhesive wear with addition of 5wt. % ZrO2 reinforcement particles.

Materials Science and Technology, Dec 26, 2019

In the present work, the influence of antimony (Sb) addition in Zn-Al-Mg alloy on the microstruct... more In the present work, the influence of antimony (Sb) addition in Zn-Al-Mg alloy on the microstructure, phase characteristic, solidification behaviour and corrosion resistance of hot dipped Zn-0.5Al-0.5Mg-xSb (x = 0, 0.1, 0.3 and 0.5 wt-%) coated steel wires were evaluated. Thermal analysis revealed that cooling rate of the liquid metal using the steel mould (5.3°C s-1) was higher than using ceramic mould (0.3°C s-1). Based on the phase analysis and verified by thermodynamic calculations, it was revealed that Zn 11 Mg 2 and Zn 2 Mg phases appeared for Zn-Al-Mg alloy at slow and fast cooling rates while, the Mg 3 Sb 2 phase was observed after addition of Sb at both cooling rates. Corrosion behaviour of the alloys determined through electrochemical measurements shows that Zn-Al-Mg alloy with 0.3 wt-%Sb has the lowest corrosion rate indicating an excellent corrosion resistance.

Journal of Materials Engineering and Performance, 2017

Materials Science and Engineering: C, 2017

In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were inves... more In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were investigated as biodegradable materials for implant applications. Compared with Zn-0.5Al (single phase), Zn-0.5Al-xMg alloys consisted of the α-Zn and Mg 2 (Zn, Al) 11 with a fine lamellar structure. The results also revealed that ternary Zn-Al-Mg alloys presented higher microhardness value, tensile strength and corrosion resistance compared to the binary Zn-Al alloy. In addition, the tensile strength and corrosion resistance increased with increasing the Mg content in ternary alloys. The immersion tests also indicated that the corrosion rates in the following order Zn-0.5Al-0.5Mg< Zn-0.5Al-0.3Mg< Zn-0.5Al-0.1Mg< Zn-0.5Al. The cytotoxicity tests exhibited that the Zn-0.5Al-0.5Mg alloy presents higher viability of MC3T3-E1 cell compared to the Zn-0.5Al alloy, which suggested good biocompatibility. The antibacterial activity result of both Zn-0.5Al and Zn-0.5Al-Mg alloys against Escherichia coli presented some antibacterial activity, while the Zn-0.5Al-0.5Mg significantly prohibited the growth of Escherichia coli. Thus, Zn-0.5Al-0.5Mg alloy with appropriate mechanical properties, low corrosion rate, good biocompatibility and antibacterial activities was believed to be a good candidate as a biodegradable implant material.

Procedia Engineering, 2017

The International Journal of Advanced Manufacturing Technology, Dec 8, 2018

Al-Mg 2 Si in situ composite is a new metal matrix composite (MMC) with numerous applications in ... more Al-Mg 2 Si in situ composite is a new metal matrix composite (MMC) with numerous applications in different engineering fields. MMCs are considered difficult-to-cut materials due to the abrasive nature of the reinforcement (e.g., Mg 2 Si), hardness, and built-up edge. Hence, electrical discharge machining (EDM) is one of the alternative ways to machine Al-Mg 2 Si. With EDM, it is possible to machine conductive materials with different strength, temperature resistance, and hardness as well as produce complicated shapes, high-aspect ratio slots, and deep cavities with precise dimensions and good surface finish. The experiments in this study were designed by response surface methodology (RSM) and ANFIS was utilized to analyze the nano-powder mixed EDM (NPMEDM) of Al-Mg 2 Si in situ composite. The study represents the impacts of NPMEDM parameters on changes in microstructure and material removal rate (MRR). The results revealed that among all interactions, the current-voltage and current-pulse ON time interactions have the most significant effect on MRR. Moreover, current has most significant effect, followed by voltage, pulse ON time and duty factor. An analysis of the Al-Mg 2 Si microstructure demonstrated that current, pulse ON time, and voltage have remarkable impact on the microstructure, size of craters, and profile of the machined surface. Moreover, decrease in spark energy leads to less microstructural change and better surface finish. Keywords Al-Mg 2 Si metal matrix composite (MMC). Nano-powder mixed electrical discharge machining (Nano-powder mixed EDM). Adaptive neuro-fuzzy inference system (ANFIS). Response surface methodology (RSM). Material removal rate (MRR). Microstructure

World Academy of Science, Engineering and Technology, International Journal of Mechanical and Mechatronics Engineering, Dec 10, 2015

ABSTRACT

Surface roughness is one of the key measures in manufacturing that describes machined surface int... more Surface roughness is one of the key measures in manufacturing that describes machined surface integrity. In this research work, the effect of silicon morphology on surface roughness when turning Al-11%Si-1.8%Cu alloy and Sr-containing alloys was investigated. The experiments are carried out under oblique dry cutting conditions using a PVD TIN-coated insert at three cutting speeds of 70, 130 and 250 m/min, feed rates of 0.05, 0.1, 0.15 mm/rev, and 0.05 mm constant depth of cut. The result released that surface roughness decreased with adding 0.04 wt.% Sr to casting. The surface roughness values reduce with cutting speed increment from 70 m/min to 250 m/min. Also, the surface finish deteriorated with increase in feed rate from 0.5 mm/rev to 0.15 mm/rev.

Solid State Phenomena, Sep 1, 2017

Advantage of Al-Mg2Si metal matrix composite (MMC) is due to the particulate reinforced Mg2Si in ... more Advantage of Al-Mg2Si metal matrix composite (MMC) is due to the particulate reinforced Mg2Si in the Al matrix that has improved mechanical properties of the in situ composite. In particular, the composite has been chosen as the structural material for automotive and aerospace components. The hypereutectic Al-Mg2Si composite should be comprised of two morphologies, namely primary Mg2Si and pseudo-eutectic Al-Mg2Si phase. However, as-received commercial Al-20Mg2Si-2Cu in situ composite contained a wide range of elements that affect the resultant microstructure of the in situ composite. In fact, four different morphologies have been identified in the in situ composites. The first phase is dark facet primary Mg2Si particles, surrounded by pseudo-eutectic Al-Mg2Si phase in lamellar structure. Along the eutectic boundary is the formation of needle-like Al5FeSi intermetallic and the phase is surrounded by Al5Mg8Si6Cu2+Al2Cu as last phase nucleated. Optical micrograph, SEM imaging, EDX analysis and elemental mapping have revealed these phases correspond to shape of morphologies and respective molecular compound.