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Showing papers in "Transactions of The Indian Institute of Metals in 2021"


Journal ArticleDOI
TL;DR: In this article, the effects of cryogenic cycling rejuvenation on the flow behavior of ZrCuAlNiAg metallic glass (MG) in the range of relaxation region from 0.7 up to 0.9 glass transition temperature (Tg) were investigated.
Abstract: In this work, the effects of cryogenic cycling rejuvenation on the flow behavior of ZrCuAlNiAg metallic glass (MG) in the range of relaxation region from 0.7 up to 0.9 glass transition temperature (Tg) were investigated. For this purpose, nanoindentation and strain-rate jump tests were carried out to show the strain response of glassy alloy. According to the jump test, the increase in applied temperature leads to the rise in induced strain in both of as-cast and rejuvenated samples. It was also uncovered that the rejuvenated sample is sensitive to the higher strain rates leading to the significant overshoot in the flow stresses. In addition, the nanoindentation results indicated that the loading process induced a significant anelastic strain in the rejuvenated sample at 0.9Tg, demonstrating the possible formation and percolation of shear transformation zones (STZs) in the rejuvenated amorphous structure.

26 citations


Journal ArticleDOI
TL;DR: In this paper, an equiatomic quinary MgAlMnFeCu high-entropy alloy (HEA) has been synthesized successfully by mechanical alloying (MA) using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS/XEDS).
Abstract: An equiatomic quinary MgAlMnFeCu high-entropy alloy (HEA) has been synthesized successfully by mechanical alloying (MA). Phase evolution of MgAlMnFeCu HEA has been studied using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS/XEDS). Milling up to 60 h leads to the formation of a mixture of two phases consisting of a BCC phase (a = 2.87 ± 0.02 A) and ϒ-brass-type phase (a = 8.92 ± 0.03 A), with ~ 2 μm powder particle size. The as-milled alloy after spark plasma sintering (SPS) at 900 °C exhibits an experimental density of 4.946 ± 0.13 g cc−1, which is 99.80% of the theoretical density. SPS leads to the formation of C15 Laves phase (MgCu2-type; a = 7.034 ± 0.02 A) and B2 (AlFe-type; (a = 2.89 ± 0.02 A) intermetallic along with the ϒ-brass-type phase. The SPSed sample has exceptional hardness value (~ 5.06 GPa), high compressive strength (~ 1612 MPa) and appreciable failure strain (~ 6.4%) coupled with relatively low density. Various thermodynamic parameters have been considered for understanding the phase evolution and their stability during MA.

23 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of the historical review of the boriding process using the Bibliometric analysis and show that the boring process has been global and fast-growing in scientific publications of the last ten years.
Abstract: The boriding process is a branch of materials heating treatments that studies the improvement of the mechanical properties in steels and alloys. Recently, the borided trends have been studied by a selected group of researchers around the world with an interest to divulge the new results on borided materials for different industrial and biomedical applications. The aim of this study is to provide an overview of the historical review of the boriding process using the Bibliometric analysis. In total, 1227 documents in the Scopus database have used the boriding process as keyword with a growth rate of 7.3% every year from 1962 to 2020. The papers were written by around 2434 authors, mainly from Mexico, Turkey, and Poland, representing 37.7% of the total publications analyzed. The data obtained show that the boriding process has been global and fast-growing in the scientific publications of the last ten years.

17 citations


Journal ArticleDOI
TL;DR: In this paper, electron beam melting (EBM) has been presented as an additive manufacturing (AM) process, powder melting enabled in a high vacuum atmosphere happens simultaneously at multiple points without compromising on surface finish, precision or build speed.
Abstract: In producing parts using 3D printing technology, electron beam melting (EBM) has been presented as an additive manufacturing (AM) process. In producing parts using the EBM process, powder melting enabled in a high vacuum atmosphere happens simultaneously at multiple points without compromising on surface finish, precision or build speed. Heat treatments on the unique microstructure and microstructure evolution, mechanical properties of produced layers such as ultimate tensile strength (UTS) by the production method, precision mechanical systems for reducing waste materials, fatigue properties in EBM methods, study of produced parts for analyzing the corrosion resistance, analysis of Surface roughness of produced parts using EBM, applications of EBM to biomaterial products and effect of EBM parameters and porous structure on mechanical properties are considered in order to develop the EBM process. EBM is a high technology increasingly employed in different industries including bioengineering, aerospace and marine not only because of its increasing efficiency in the process of part production but also because of its time and cost-efficient accurate production results. Moreover, time and cost of accurate production can be decreased as a result of increasing efficiency in process of part production. However, despite the quantity of research in this area, there are few papers reviewing the achievements. Therefore, this paper reports on recent achievements in production of EBM processed Ti–6A1–4V parts.

13 citations


Journal ArticleDOI
TL;DR: An equiatomic low-density high-entropy alloy (LDHEA) was synthesized by mechanical alloying (MA) and consolidated by spark plasma sintering (SPS) techniques as discussed by the authors.
Abstract: An equiatomic Mg20Al20Si20Cr20Fe20 (at.%) low-density high-entropy alloy (LDHEA) was synthesized by mechanical alloying (MA) and consolidated by spark plasma sintering (SPS) techniques. The phase identification, chemical composition, fine microstructural features and thermal stability of the mechanical alloyed powder and the spark plasma sintered (SPSed) compacts were discerned through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) techniques. The LDHEA powder after mechanical alloying for 60 h exhibited a nanocrystalline BCC phase (a = 0.2887 ± 0.005 nm) as a major one along with the minor fraction (~ 3%) of undissolved Si. The 60-h milled powder was consolidated through SPS at 800 ℃ (1073 K). The SPSed sample exhibited the presence of a major B2-type AlFe phase (cP2; a = 0.2889 nm) along with a parent disordered BCC phase and a minor amount of Al13Fe4 (mC102; a = 1.549 nm, b = 0.808 nm, c = 1.248 nm), β-Al3Mg2 (cF1168; a = 2.824 nm) and Cr5Si3 (tI32; a = 0.917 nm, c = 0.463 nm) phases. Attempts were made to explore the mechanical properties of the LDHEA through microindentation techniques. The hardness and yield strength were evaluated to be ~ 7 GPa and ~ 2100 MPa respectively. The density of the sintered sample was found to be around 4.38 g cm−3, which is around 99.98% of the theoretical density. The phases evolved during MA and SPS were explained with the help of the thermodynamic parameters and property diagrams generated through the CALPHAD approach using Thermo-Calc software.

13 citations


Journal ArticleDOI
TL;DR: In this article, a microstructural examination exposed the presence of ferrite, intragranular austenite, Widmanstatten austenites, grain-boundary Austenite and secondary Austenites.
Abstract: The oil and gas industries have been extensively utilizing 25Cr super duplex stainless steels because of their excellent mechanical properties and corrosion resistance. Wire arc additive manufacturing technology was employed to fabricate thin wall using ER2594 filler wire. The microstructural examination exposed the presence of ferrite, intragranular austenite, Widmanstatten austenite, grain-boundary austenite and secondary austenite. It was found that the austenite-ferrite fraction varied across the wall due to the complex cyclic thermal history during deposition. Detrimental phases such as sigma-σ or lambda-λ were not observed due to lower heat input and suitable inter-pass temperature. Micro-hardness measurements showed the gradual variation of hardness along the built direction (281–310HV0.2). Tensile specimens exposed anisotropy, and the tensile properties were better than the wrought counterparts and meet the minimum requirements as mentioned in ASTM A240/A240M-20a and ANSI/NACE MR0175/ISO 15156-1:2015.

13 citations


Journal ArticleDOI
TL;DR: In this article, the effect of various micro-structural features of the Ti2AlNb intermetallics on room temperature properties, such as strength, ductility, and fracture mechanisms, was analyzed.
Abstract: Ti2AlNb intermetallics are promising next-generation aerospace materials. Advancement in non-conventional manufacturing methods has made the fabrication of these intermetallics economical. However, post-heat treatments are required to obtain desired mechanical properties, which further depend on the microstructural features of the intermetallics. Extensive studies have been conducted to understand the relation between mechanical behavior and microstructural features of this intermetallic. This review presents the effect of various microstructural features of (a) fully B2 and α2 + B2, (b) fully lamellar, (c) bimodal lamellar, (d) equiaxed and duplex, and (e) plate-like O phase on room temperature properties, namely strength, ductility, and fracture mechanisms. Moreover, the review emphasizes the special microstructural features that are required to enhance the mechanical properties of the alloy.

12 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of cutting parameters and insert types on the surface roughness and cutting force components were investigated during hard turning of high chromium AISI D2 tool steel under dry cutting conditions.
Abstract: In this experimental study, the effects of cutting parameters and insert types on the surface roughness and cutting force components were investigated during hard turning of high chromium AISI D2 tool steel under dry cutting conditions. Three different cutting speeds, feed rates, and cutting depths were chosen as machining parameters, while cubic boron nitride and ceramic inserts with two different nose radii were selected as tool material. The design of the experiment was carried out based on the Taguchi L36 mixed orthogonal array. The response surface method was used to establish the relation between input and output parameters. Analysis of variance was performed to show the most significant parameters on the response. In addition, an artificial neural network was implemented for output modeling. The results revealed that surface roughness was mainly affected by the feed rate with almost 90.53%. Following feed rate, the nose radius was also significant on the surface roughness. Based on the results, the cubic boron nitride insert exhibited better performance than the ceramic insert in terms of minimum surface roughness. The cutting force components were mostly affected by the insert type. Cubic boron nitride insert caused greater forces during machining compared to the ceramic insert. The results revealed that the artificial neural network and response surface methodology exhibited very good accuracy with experimental data. However, the artificial neural network shows better accuracy and can predict the responses with 99.51% accuracy.

12 citations


Journal ArticleDOI
TL;DR: In this article, an experimental analysis done on dry sliding wear behavior of aluminium matrix composites reinforced with WC (tungsten carbide) particles is presented. And the derived optimal wear properties to improve the sliding wear performance of the composites through a novel hybrid (GRA integrated TLBO) multi-response optimization approach are in a closer correlation with the experimentally measured values.
Abstract: This investigation deals with an experimental analysis done on dry sliding wear behaviour of aluminium matrix composites reinforced with WC (tungsten carbide) particles. The composites were processed through powder metallurgy (P/M) technique with the addition of various fractions of WC particles. Results of scanning electron microscope (SEM) examinations and XRD analysis showed better dispersion of the reinforced particles and good matrix–reinforcement interface integrity. The results of dry sliding wear tests conducted on composite samples were analysed for varied conditions of WC volume fraction and sliding distance. The wear properties of composites were significantly affected by the variation of the WC volume percentage (5–25%). Smother wear tracks and closely spaced grooves on the composite pin worn surfaces were found for higher volume fraction WC particles. The postulated regression models for prediction of wear behaviour approximate their experimental values with an estimated error from 1.97 to 6.56%. The derived optimal wear properties to improve the sliding wear performance of the composites through a novel hybrid (GRA integrated TLBO) multi-response optimization approach are in a closer correlation with the experimentally measured values. Also, wear performance predicted values through hybrid multi-response optimization are closer to their validation experimental results compared with the predicted values through TLBO and GRA approaches. The derived optimal set of wear properties are 1.921 mm3/m wear rate and 0.292 coefficient of friction at 15 vol% of WC, 10 N applied load, 775 m sliding distance, and 1 m/s sliding velocity. The surfaces of the composite samples tested at the derived set of optimal wear behavioural parameters were also examined through SEM and analysed.

12 citations


Journal ArticleDOI
TL;DR: In this paper, a surface modification of high-strength aluminium alloy 7075-T6 by plasma electrolytic oxidation (PEO) and type II hard anodization (HA) is presented.
Abstract: Surface modification of high-strength aluminium alloy 7075-T6 by plasma electrolytic oxidation (PEO) and type II hard anodization (HA) is presented in the current work. PEO-based ceramic oxide coatings were fabricated by employing an alternating current (AC) power source with a current density of 300 mA/cm2. The concentration effect of electrolytes on the alumina coatings was investigated and optimized comprehensively. Three separate aqueous electrolytes with 1:3, 1:1 and 3:1 proportions of sodium silicate (Na2SiO3) and potassium hydroxide (KOH) were utilized to evaluate optimum electrolyte concentration for obtaining desired AC-PEO coatings. X-ray diffraction (XRD) was utilized to investigate the phase composition of the coatings. Field emission scanning electron microscopy (FESEM) was employed to investigate the surface and cross-sectional characteristics of oxide coatings. Scratch testing was used to assess the oxide coatings' adhesion ability, and potentiodynamic polarization (PDP) was utilized to assess the coatings' corrosion behaviour in a 3.5 wt% aqueous NaCl solution. Among the AC-PEO and HA coatings, the AC-PEO specimen fabricated with equal ratios of sodium silicate and KOH concentration (Na2SiO3:KOH 1:1) showed excellent adhesion strength (critical load, Lc = 41.5 N) along with the remarkable corrosion resistance (corrosion current density, icorr = 5.63 × 10–6 mA/cm2).

11 citations


Journal ArticleDOI
TL;DR: In this article, a two-stage stir casting (melt stirring) technique is adopted to produce the composites, and the weight percentage of reinforcement is maintained at 9, 12, and 15 to know the effect of varying weight percentage on microstructure and wear behavior.
Abstract: The current research work primarily focuses on synthesizing and exploring Al2014 alloy microstructure and wear behavior reinforced with 20 μm Al2O3 (alumina) particles. A novel two-stage stir casting (melt stirring) technique is adopted to produce the composites, and the weight percentage of reinforcement is maintained at 9, 12, and 15 to know the effect of varying weight percentage on microstructure and wear behavior. To achieve better dispersion, alumina particles have been introduced in two stages. X-ray diffraction (XRD) and electron microscope/energy-dispersive spectroscope (EDX) are used to characterize the prepared composites. In the Al2014 matrix, microstructural characterization showed a fairly uniform dispersion of Al2O3p. The presence of alumina is confirmed by the XRD pattern carried out on the produced composite (Al2014-15 wt.% Al2O3p). Wear properties of as-cast Al2014 alloy and composites (Al2014-Al2O3p) at 9, 12, and 15 wt.% have been studied. Dry sliding wear tests have been conducted over a load range of 9.81 N-49.05 N and sliding speed of 100–600 RPM using pin-on-disk machine. Results revealed the frictional coefficient of as-cast Al2014 alloy and produced composites increase with an increase in load up to 49.05 N. Nevertheless, the frictional coefficient of both as-cast Al2014 alloy and produced composite increase continuously by increasing the speed. The wear rate of both Al2014 matrix alloy and Al2014-Al2O3 reinforced composite increase with the increase in load and sliding speed. To know the possible wear mechanisms, worn surface and wear debris have been studied by using electron microscopy and EDS examination to specify the formation of the oxides.

Journal ArticleDOI
TL;DR: In this paper, flow curves of an equiatomic Ti-Ni shape memory alloy after deformation by compression in the temperature range from 100 to 900°C at a strain rate of 1 s−1 and up to a true strain (e) of 0.9 were obtained.
Abstract: In the present work, flow curves of an equiatomic Ti–Ni shape memory alloy after deformation by compression in the temperature range from 100 to 900 °C at a strain rate of 1 s−1 and up to a true strain (e) of 0.9 were obtained. The phase composition, mechanical and functional properties after compression to e = 0.5 were studied. The boundaries of the temperature ranges of the development of dynamic softening processes were determined, as follows: dynamic recovery in 100–300 °C range; dynamic polygonization in 300–500 °C range and dynamic recrystallization above 500 °C. An optimum deformation temperature range in terms of accumulation of high strains and achieving improved functional properties is 300–500 °C. It has also been found that post-deformation annealing at temperatures above the deformation temperature leads to the decrease in the B2-austenite lattice defectness and to a significant increase in shape recovery characteristics.

Journal ArticleDOI
TL;DR: Inconel alloys are one of the materials of choice for high temperature applications whether it is aerospace, nuclear or gas turbine as discussed by the authors, due to their excellent mechanical and non-corrosion properties even under harsh environments at elevated temperatures.
Abstract: Inconel alloys are one of the materials of choice for high temperature applications whether it is aerospace, nuclear or gas turbine. This is due to their excellent mechanical and non-corrosion properties even under harsh environments at elevated temperatures. Joining Inconel alloys through conventional fusion welding techniques have posed many different problems and hence, solid state joining processes could well be an alternative welding method for these alloys, wherever the design permits. Friction welding being a solid state welding process, is well established for its capability of producing high quality welds and joining dissimilar metals. In this paper, Inconel alloys are introduced initially, and then friction welding in general has been discussed. Thereafter, the published works on the friction welding of Inconel alloys are reviewed with an emphasis on microstructural and mechanical properties of similar and dissimilar Inconel weld joints.

Journal ArticleDOI
TL;DR: In this article, the importance of post AM double aging heat treatment (HT) of alloy Inconel 718 (IN718) fabricated through laser-based powder bed fusion process (L-PBF) was delivered.
Abstract: Manufacturing defects, heterogeneous microstructure, and micro-segregation of secondary laves phases are the major issues to be resolved during the fabrication of alloy Inconel 718 (IN718) fabrication through metal additive manufacturing (AM). The present study delivers the importance of post AM double aging heat treatment (HT) of alloy IN718 fabricated through laser-based powder bed fusion process (L-PBF). Initially, the as-built IN718 sample was subjected to solution annealing at 980 °C for the duration of 1 hour followed by air cooling. Then, the L-PBF sample was subjected to double aging at 720 °C for 8 hours followed by furnace cooling to 620 °C in 2 hours. The specimen was kept at 620 °C for 8 hours and then cooled to room temperature. The beneficial influence of HT on the closure of AM-induced manufacturing defects such as pores and voids, microstructural changes, and microhardness have been reported. As-built microstructure showed the presence of heterogeneous columnar dendrites along the build direction with the presence of a large number of laves phases in the interdendritic regions. HT microstructure resulted in the formation of homogeneous austenite gamma (γ) matrix in which the strengthening phases such as gamma prime (γ′) (Ni3 (Al, Ti)) and gamma double prime (γ″) (Ni3Nb) were observed. As a result of HT, laves phases ((Ni, Fe, Cr)2·(Nb, Mo, Ti)) were dissolved in the grain interiors and precipitated in the grain boundaries as delta (δ) phase (NbNi3). The δ phase in the grain boundaries arrested the grain boundary dislocation, as well as grain growth, and revealed the relatively finer and homogenous grain structures. Further, a Micro-computed tomography (micro CT) examination revealed the absence of AM-induced pores after HT. The hardness of the heat-treated samples was increased to 35% and it showed an increase in hardness from 417 to 564 HV. Dimensional analysis was performed on the alloy IN718 to study the effect of thermal loading. The volumetric shrinkage of 3.084% was noted as a result of heat treatment at the micron-scale.

Journal ArticleDOI
Shaopeng Gu1, Liang Yu1, Guanghua Wen1, Ping Tang1, Zhe Wang1, Gao Zhubing 
TL;DR: In this article, the qualitative and quantitative analysis of volatiles in the most commonly used CaO-SiO2-CaF2-Na2O slag was conducted with thermogravimetric analyzer-mass spectroscopy (TG-MS), X-ray diffraction (XRD), scanning electron microscope with energy-dispersive spectroscopic (SEM-EDS) and FactSage, followed by giving the mechanism of fluorine volaticles in mold fluxes during the actual casting process.
Abstract: The volatilization problem of mold fluxes extremely affects their physicochemical properties and then the quality of steel shells and casting process Therefore, in this paper, the qualitative and quantitative analysis of volatiles in the most commonly used CaO–SiO2–CaF2–Na2O slag was conducted with thermogravimetric analyzer–mass spectroscopy (TG–MS), X-ray diffraction (XRD), scanning electron microscope with energy-dispersive spectroscopy (SEM–EDS) and FactSage, followed by giving the mechanism of fluorine volatiles in mold fluxes during the actual casting process The results showed that the fluorine volatiles were formed when the temperature was higher than 1000 °C The species of fluorine volatiles were SiF4 and NaF Moreover, the total volatiles content of fluorine for sample B with Na2O was 941%, being much larger than that of 153% for sample C without Na2O For sample B, the content of NaF was much larger than that of SiF4 It was because of the reaction between Na2O and CaF2 SiF4 with a low boiling point of − 65 °C could pass through the slag layer and enter air directly However, when NaF passed through the sinter layer or powder slag layer, NaF would convert into liquid or solid state, reenter molten slag and continuously repeat this process due to their high melting point of 993 °C

Journal ArticleDOI
TL;DR: In this paper, the commercially pure magnesium (Mg) was successfully processed through equal channel angular pressing (ECAP) at a set of warm temperature and back pressure up to four passes in different routes.
Abstract: The commercially pure magnesium (Mg) was successfully processed through equal channel angular pressing (ECAP) at a set of warm temperature and back pressure up to four passes in different routes. The microstructural, mechanical and wear behavior has been investigated with respect to the number of passes and the processing route. The samples have displayed substantial grain refinement, improved mechanical properties and wear resistance after the ECAP process. The fractographs of tensile samples confirmed fracture mode as a ductile–brittle mixed fracture. The X-ray line profile analysis demonstrates that modifications in the microstructure after ECAP contribute to the improved mechanical properties. The sample processed in route BC exhibits improved mechanical and wear properties owing to its refined microstructure and maximum microhardness.

Journal ArticleDOI
TL;DR: In this article, the effects of pre-deformation amount on microstructure and tensile properties during RRA heat treatment on Al-7075 alloy with T651 heat treatment were investigated.
Abstract: In this study, microstructural transformations, hardness and tensile properties of Al-7075/T651 alloy were investigated by applying different RRA (retrogression and re-aging) heat treatment procedures. The conventional RRA method involves 10 min of retrogression of the sample at 200 °C, followed by room temperature quenching and re-aging at 120 °C for 2–32 h, respectively. RRA heat treatment applied with pre-deformation effect was carried out with two different methods and deformation rates. Thus, the effects of pre-deformation amount on microstructure and tensile properties during RRA heat treatment on Al-7075 alloy with T651 heat treatment were investigated. Distribution of secondary phases, dislocation density, micro-strain and interplanar peaks were calculated by XRD analysis. During the RRA heat treatment, the break elongation value of the alloy increased by up to 20% with the applied pre-deformation amount of 5%.

Journal ArticleDOI
TL;DR: In this paper, Al7010/B4C/BN hybrid metal matrix nanocomposites with varying weight percents (wt%) of 0, 0.5, 1.0 and 1.5 of B4C and BN nanoparticles were prepared by ultrasonic assisted stir casting technique.
Abstract: In the present investigation, Al7010/B4C/BN hybrid metal matrix nanocomposites with varying weight percents (wt%) of 0, 0.5, 1.0, 1.5, 2.0 and 2.5 of B4C and BN nanoparticles were prepared by ultrasonic-assisted stir casting technique. For the prepared composites, the microhardness and the tribological characteristics were reported. The wear behavior was determined under normal loads of 10, 20, 30 and 40 N and at sliding speeds of 0.5, 1.0 and 1.5 m/s, respectively. The results showed an increase in wear resistance and decrease in friction coefficient with the addition of the nanoparticles. The wear rate and friction coefficient increased with increase in normal load and sliding speed. The scanning electron microscope (SEM) images revealed uniform dispersion of the reinforcement particles in the composite. The wear specimens showed adhesion and plowing behavior at lower loads and delamination at higher load.

Journal ArticleDOI
TL;DR: In this article, three-dimensional isothermal steady-state flow simulations, residence time distribution analysis and inclusion transport simulations of tundish flow are conducted, and the simulation results are validated with experimental measurements reported in literature.
Abstract: In continuous casting process, cleanliness of steel can be improved and maintained by promoting the inclusion separation inside the tundish by various means; tundish flow optimization using arrangement of flow control devices inside the tundish is one among them. Three-dimensional computational fluid dynamics simulation of tundish flow is an efficient way to investigate the arrangement of flow control devices. In the present work, three-dimensional isothermal steady-state flow simulations, residence time distribution analysis and inclusion transport simulations of tundish flow are conducted. All the simulation results are validated with experimental measurements reported in literature. Subsequently, the simulations are extended for a non-isothermal flow of the existing tundish in the plant and an additional flow control device, namely a weir with appropriate dimensions is proposed which indicated better steel flow in the tundish with more inclusion separation efficiency as compared to the existing bare tundish.

Journal ArticleDOI
TL;DR: In this paper, spheroidal graphite cast iron (GGG-40) was employed as reinforcement material in tin bronze (CuSn10) matrix system, and the results of the analyses revealed that increased ultrasonic cleaning time improves the consolidation quality of metallic chips and provides successful covering of GGG-40 chips by the CuSn10 chips as a result of better structural integrity.
Abstract: The aim of this study is to produce composite materials by recycling metallic chips, which are found in industry as a large amount of waste. In addition, it is aimed to investigate the effect of ultrasonic cleaning process as the consolidation behavior and mechanical properties of bulk material directly depend on the cleaning of waste metallic chips. In the present investigation, spheroidal graphite cast iron (GGG-40) was employed as reinforcement material in tin bronze (CuSn10) matrix system. GGG-40 and CuSn10 chips were cleaned by ultrasonic agitation in water for 20 and 40 min. Consolidation of the cleaned metallic chips was achieved with a hot press by applying 820 MPa pressure under 450 °C, and the cylindrical and prismatic metal matrix composite materials with different reinforcement ratios were successfully produced. Energy-dispersive X-ray and scanning electron microscopy analyses were carried out to determine the amount of the oxide removed from the surfaces of chips. The mechanical properties of the samples were determined by hardness, porosity, compression and three-point bending tests. According to the results of the analyses, it was found that CuSn10 surfaces were cleaned from 20%, 50% and GGG-40 surfaces from 35%, 39% oxides during 20- and 40-min cleaning time, respectively. In addition, the results of the mechanical tests revealed that increased ultrasonic cleaning time improves the consolidation quality of metallic chips and it provides successful covering of GGG-40 chips by the CuSn10 chips as a result of a better structural integrity. New machinery parts with high mechanical properties can be produced as a result of recycling of the metallic chips which are available as waste in industry by appropriate cleaning process and this situation makes this study more innovative, economical and environmentally friendly research.

Journal ArticleDOI
TL;DR: In this paper, the effect of the percentage of stearic acid (SA) is investigated on the density, strength, hardness, rheological properties, and microstructure of a part made by 4605 low-alloy steel powder using the MIM process.
Abstract: Nowadays, the metal injection molding (MIM) process is a manufacturing method to produce complex shape components. Feedstock preparation in this process is vital because produced feedstock defects can be detrimental in the following processing steps. In this study, effect of the percentage of stearic acid (SA) is investigated on the density, strength, hardness, rheological properties, and microstructure of a part made by 4605 low-alloy steel powder using the MIM process. For this reason, feedstock with different percentages of SA from 1 to 17% has been produced. Mechanical and physical properties show that SA, as a surfactant, has two impacts on the results. SA from 1 to 9% improves the powder particle’s distribution in the binder system and increases the strength and density of the sintered bodies. The results also indicate that with more surfactant growth, the density and strength dramatically decrease due to lower carbon in the sintered parts. The carbon content determines the final sample’s microstructure, which has a substantial influence on the properties. Besides, it can be inferred from the results that the hardness lessens with a gentle slope as the amount of SA in the binder system increases. From the perspective of rheological properties, more SA results in higher sensitivity of feedstocks to the shear rate.

Journal ArticleDOI
TL;DR: In this paper, the flexural properties of inter-ply hybrid polymer composites are investigated and post-failure analysis of composites using a scanning electron microscope is done to understand the fractographic behavior of the samples.
Abstract: Advanced fiber-reinforced polymer composites are stronger, durable and lighter than their metallic counterparts. Inter-ply hybrid polymer composites are formed by more than one type of fiber plies reinforced in the same matrix. The durability and integrity of the altered stacking sequence and hybrid ratio of such composites at low temperature conditions have not been widely explored. In this research work, flexural behavior of cryogenic conditioned glass and/or carbon fibers-based hybrid composites has been studied. Substituting two glass fiber plies with those of carbon on the top side of glass/epoxy (GE) composite, denoted as (C2G3), achieved the maximum flexural strength of 491.94 MPa (27.82% higher than unconditioned neat GE composite) after 8 h of conditioning, and the highest flexural modulus of 33.52 GPa was attained by C1G3C1 composite. A detailed analysis of the effect of conditioning duration and stacking sequence of the hybrids on the flexural properties was done and the underlying mechanisms were discussed. Post-failure analysis of composites using a scanning electron microscope was done to understand the fractographic behavior of the samples. Finally, elemental analysis was used to measure nitrogen incorporation within the matrix as a function of conditioning duration.

Journal ArticleDOI
TL;DR: In this paper, the authors address some of the key technical issues that are currently limiting the prolific usage of additive manufacturing as a successful vehicle for accelerated progress in turbine engine performance, and present a review of these issues.
Abstract: Gas turbine engine advancements have been enabled by innovation in materials and manufacturing technologies. The evolution of additive manufacturing (AM) has changed the face of direct digital technologies for the rapid production of models, prototypes, and functional parts including repair and maintenance for turbine engines. Metal 3D printing is poised to be an enabler for the next industrial revolution in enabling advancements in turbine engine performance. While there has been tremendous efforts on research and development in utilizing this versatile technology, the number of qualified metallic parts that are running in the engine has not been commensurate with the applied research and development efforts and the benefits that the AM technology offers. This review addresses some of the key technical issues that are currently limiting the prolific usage of AM as a successful vehicle for accelerated progress in gas turbine engines.

Journal ArticleDOI
TL;DR: In this article, a gas metal arc welding with cold metal transfer (GMAW-CMT) process is used for joining dissimilar thickness of dissimilar metals for achieving higher mechanical strength by using properties of both the metals.
Abstract: Nowadays, CMT is used for joining dissimilar thickness of dissimilar metals for achieving higher mechanical strength by using properties of both the metals. Joining of dissimilar aluminium alloys with dissimilar thickness by using gas metal arc welding with cold metal transfer (GMAW-CMT) process, is the primary objective of this work. CMT butt joining of 6061-T6 (3.18 mm) and 6082-T6 (2 mm) aluminium alloys was carried out by using ER4043 (Al–5%Si) wire. Mechanical properties and microstructural characterization were carried out for the weld bead. Microstructural examination at different weld zones is studied using optical microscope and field emission scanning electron microscope (FESEM). Macro-structural images were captured to study the weld bead geometry in relation to heat input. Mechanical properties were examined by Vicker’s microhardness and tensile test (with reinforcement, that is, the actual profile of the bead and without reinforcement, that is, the profile of bead are flattened to the surface of the plate). The residual stresses were measured using high-resolution X-ray diffraction (HR-XRD) method. Results showed significant changes in mechanical properties when heat input was in the range of 120–130 J/mm. Removal of reinforcement height improved almost 7–11% of tensile strength. Compressive residual stresses were experienced in the weldment. Comparatively cold metal transfer (CMT) showed better residual stress results than metal inert gas (MIG) welding at the same heat input.

Journal ArticleDOI
TL;DR: A review of the present understanding on high-density bulk metallic glass (BMG) composites with a specific emphasis on their application in kinetic energy (KE) penetrators is presented in this paper.
Abstract: A review of the present understanding on high-density bulk metallic glass (BMG) composites with a specific emphasis on their application in kinetic energy (KE) penetrators is presented. The paper deals with materials requirement for producing KE penetrator and the need to use high-density BMG to enhance the depth of penetration using the concept of “self-sharpening” behavior caused by shear band formation. The initial sections have been devoted to the description of different BMGs, their formability, processing and mechanical properties. This is followed by a brief account on the evolution of high-density BMG, their composites and their possible application in ammunition. Finally, the contribution of the present group in light of processing and evaluation of high-density BMG composites for above-mentioned application have been highlighted.

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TL;DR: In this paper, a hybrid artificial neural network (ANN) coupled GA approach was used to optimize the multi-objective characteristics of wire electrical discharge machining (WEDM) in SLM-fabricated AlSi10Mg.
Abstract: This work attempts to optimize the multi-objective characteristics of wire electrical discharge machining (WEDM) in SLM-fabricated AlSi10Mg through a hybrid artificial neural network (ANN) coupled genetic algorithm approach. The SLM is unambiguously one of the most effective commercially viable successful additive manufacturing (AM) technologies that have the potential to replace many traditional methods of manufacturing. However, the highly intricate metallic support structures created in SLM are too strong to be eliminated by hands for which precision machining operations such as WEDM are widely employed for post-processing of SLM–AlSi10Mg. The Taguchi experimental design, considering the three most influencing factors, is performed to obtain micro-hardness and surface roughness results. The input factors for optimization are discharge current, discharge voltage, and pulse time-on in the WEDM process. The multi-objective optimization is performed using the ANN coupled GA approach where the ANN model has been generated first and the results of the best model are fed to GA for optimization. For this, five variants of three-layered, multi-perceptron models with feed-forward (BP) neural structures are also developed. The current model is supplemented with a Levenberg–Marquardt algorithm that uses logarithmic sigmoid (logsig) and linear (purelin) transfer functions. Finally, the response values from the best ANN model (3–10–2) are employed for multi-objective optimization using GA. The present study establishes the following optimized process parameters: 12 A discharge current, 42 V discharge voltage, and 12 µs time-on for maximized micro-hardness of 478 VHN and minimized surface roughness of 4.3 µm, both with greater than 98% confidence level. The present study reports briefly phase characterization such as the presence of Si particles, α-Al, and Mg2Si phases on the recast surface. The surface quality of the optimized specimen exhibits superior surface quality than its other experimental counterparts.

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TL;DR: In this article, a 90% Cr3C2-10% NiCr-based laser clads were developed with and without preheating the substrate T91, where the substrate was preheated at 200°C, 400°C and 600°C temperature before clad deposition.
Abstract: High cooling speed in laser cladding process yields excellent metallurgical and mechanical properties. Indeed, this attribute along with the process’s additive nature contributes significantly to the development of thermal stresses that are the major cause of any possible crack and delamination formation across the deposition. This limitation is more common for additive materials such as chromium carbide which are crack-sensitive by nature during most of the hard facing process. In the current work, A 90 wt% Cr3C2–10 wt% NiCr-based laser clads were developed with and without preheating the substrate T91. In the case of preheating, the substrate was preheated at 200 °C, 400 °C, and 600 °C temperature before clad deposition. Liquid dye penetration test was carried out on the developed composite clads, whereas 20 numbers of cracks per unit length were observed on without preheated substrate. The microstructure studies revealed that the preheated substrates have shown a crack-free structure as compared to those without preheating of the substrate. The clad height, heat-affected zone, and dilution rate were found reliable in the case of cladding developed at preheated temperature (200 °C) as compared to higher preheated temperature (400 °C and 600 °C). Energy-dispersive X-ray spectroscopy study cleared that the chromium-rich phases were more segregated with iron and nickel elements on the developed clad on the preheated surface as compared to the surface developed on without preheating of the substrate. The average microhardness of the developed composite laser clads with and without preheating of the substrate was 802 ± 94 HV and 878 ± 68 HV, respectively. This was found to be much higher than the substrate microhardness (439 ± 12 HV).

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TL;DR: In this paper, an unsteady-state mathematical model was developed to describe the moisture transport phenomena during the iron ore sintering, and the model was then validated using experimental data from laboratory Sintering pot tests.
Abstract: The cold permeability of a sinter bed is a complex function of the granules’ effective mean diameter and bed moisture. The binding force provided by moisture before fusion commences crucial in determining the strength of a sinter. However, excess moisture is detrimental to the propagation of the heat front, because it reduces the bed’s permeability. The source of moisture can be either the inherent moisture in the bed or from the incoming gases due to suction in the bottom of the bed. An unsteady-state mathematical model was developed in the current study to describe the moisture transport phenomena during the iron ore sintering. The model was then validated using experimental data from laboratory sintering pot tests. Using the help of the model, the effect of humidity on the moisture characteristics was then investigated. The temperature profiles revealed that the change in the solid temperatures was less than 5% with increasing humid conditions.

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TL;DR: In this paper, a solid cylindrical AA7075 aluminum alloy bar and some SiC powder has been produced by the process of friction stir back extrusion (FSBE) to examine the microstructural properties of samples, both the scanning electron microscopy and optical microscopy were applied.
Abstract: Friction stir back extrusion (FSBE) is a newfangled method to produce high strength tubes with a fine-grained structure. In the following experiment, using a solid cylindrical AA7075 aluminum alloy bar and some SiC powder, the Al-SiC composite tube has been produced by the process of FSBE. To examine the microstructural properties of samples, both the scanning electron microscopy and optical microscopy were applied. Microhardness and tensile tests were also used to assure mechanical properties of the tubes. Furthermore, the phase analysis of samples was carried out via the X-ray diffraction technique. It was observed that SiC particles were almost distributed homogeneously among the aluminum phase. In addition, grains sizes of the composite tube were decreased in comparison with the aluminum tube. The XRD pattern analysis of the composite specimen demonstrated that the peaks of Al and SiC appear as the main phase and then new phases of Al4C3 and Al4SiC4 will emerge subsequent to the process.

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TL;DR: In this paper, a three-layer Ni-Cr-Mo clads was used for carbon steels in the oil and gas industry due to the high resistant corrosion. But the results of chemical analysis across some dendrites and interdendritic regions confirmed that the contents and distribution of secondary phases were insignificant.
Abstract: Ni–Cr–Mo clads are commonly used on carbon steels in the oil and gas industry due to the high resistant corrosion. In this study, a three-layer Ni–Cr–Mo clad was deposited using the GMAW process. The welding current of 200 A, the welding speed of 35 cm/min, and the electrode extension of 20 mm, as well as the torch angle of 25°, are utilized to obtain a low dilution. The results showed that Fe content in the second and third layers of the clad was below 2 wt%. The segregation of Nb and Mo to interdendritic regions contributed to the formation of secondary phases, such as Laves and MC carbide precipitates. The results of chemical analysis across some dendrites and interdendritic regions confirmed that the contents and distribution of secondary phases were insignificant. Also, the transition region where the chemical composition significantly changes to reach the composition of the first layer of the clad is apparent. The microstructure of this region changes from the planar to cellular. The corrosion behavior of the clad was investigated, and it was found that corrosion resistance is not affected when the Fe content is restricted to below 2%. A passive layer consisting of Mo, Nb, Ni and Cr with O is formed on the corroded surface.