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Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs. [ABSTRACT FROM AUTHOR]

Conventional heat treatment is not capable of converting a sufficient amount of retained austenite into martensite in high-carbon or high-carbon and high-alloyed iron alloys. Cryogenic treatment induces the following alterations in the microstructures: (i) a considerable reduction in the retained austenite amount, (ii) formation of refined martensite coupled with an increased number of lattice defects, such as dislocations and twins, (iii) changes in the precipitation kinetics of nano-sized transient carbides during tempering, and (iv) an increase in the number of small globular carbides. These microstructural alterations are reflected in mechanical property improvements and better dimensional stability. A common consequence of cryogenic treatment is a significant increase in the wear resistance of steels. The current review deals with all of the mentioned microstructural changes as well as the variations in strength, toughness, wear performance, and corrosion resistance for a variety of iron alloys, such as carburising steels, hot work tool steels, bearing and eutectoid steels, and high-carbon and high-alloyed ledeburitic cold work tool steels. [ABSTRACT FROM AUTHOR]

To increase the coating thickness and service life of the FeNiCrMo coating, a plasma transferred arc (PTA) double-track alloying technique was employed to enhance the surface triboperformance of the ductile iron. Optical microscopy (OM), X-ray diffraction (XRD), electron probe X-ray microanalyzer (EPMA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers hardness tester, and tribological tester were subsequently used to evaluate the effect of the double alloying treatment tracks on the microstructure and triboperformance of the coating. The results indicate that the content of the cementite in the sample with a double-track treatment increases 3.90 wt.% and the content of the martensite decreases 13.04 wt.% compared with the sample with a single-track treatment, which results in the maximum microhardness of the sample fabricated by double track increasing from 837 ± 10 HV0.2 for the sample fabricated by single track to 871 ± 7 HV0.2. Thus, the wear rate is lower than that of the sample with a single-track treatment. In addition, the distribution of alloying elements is more uniform and coating thickness is higher in the double track than those of the single-track-treated one. Therefore, the double-track PTA alloying treatment is favored for hardfacing ductile iron with a FeNiCrMo alloy coating due to its enhanced triboperformance and longer service life. [ABSTRACT FROM AUTHOR]

The current research work presents a detailed study of the development and wear performance of Al2O3 reinforced AZ91 Magnesium metal matrix composites. The fabrication of composites was performed using the ultrasonic-assisted stir casting process with optimized parameters. The Al2O3 reinforcement powder was varied in wt% of 0.75, 1.5, and 2.25, respectively. Different parametric combinations of stirrer speed, ultrasonic power, and reinforcement concentration were used to fabricate the composites as per the Taguchi L9 design matrix. These parameters were found to influence the distribution of the reinforcement particulates, resulting in the varying microstructure and wear resistance of the composites. The wear behaviour of composites was examined against the rotating EN-32 counterface steel disc of a pin-on-disc tribometer. The SEM, XRD, and EDX analyses were performed to analyze their surface morphologies, microstructures, phases, and elemental compositions. The enhancement in wear resistance was attributed to the uniform dispersion of particulates owing to the ultrasonic agitations. The microstructural images of the worn-out specimens elucidated the formation of wear tracks on the composite surface, which were caused by adhesion, micro-cutting of the soft matrix, oxidation, and delamination during sliding wear testing. The material removal has also occurred due to the pull-out of Al2O3 reinforcement particles and eruption of soft AZ91 Mg matrix. The composite developed at higher reinforcement concentration has shown a relatively smoother surface with light wear tracks and small agglomerations. [ABSTRACT FROM AUTHOR]

Due to the engine's start/stop system and a sudden increase in speed or load, the development of alloys suitable for engine bearings requires excellent tribological properties and high mechanical properties. Including additional elements in the Al-rich matrix of these anti-friction alloys should strengthen their tribological properties. The novelty of this work is in constructing a suitable artificial neural network (ANN) architecture for highly accurate modeling and prediction of the mechanical properties of the bearing aluminum-based alloys and thus optimizing the chemical composition for high mechanical properties. In addition, the study points out the impact of soft and more solid phases on the mechanical properties of these alloys. For this purpose, a huge number of alloys (198 alloys) with different chemical compositions combined from Sn, Pb, Cu, Mg, Zn, Si, Ni, Bi, Ti, Mn, Fe, and Al) were cast, annealed, and tested for determining their mechanical properties. The annealed sample microstructure analysis revealed the formation of soft structural inclusions (Sn-rich, Sn-Pb, and Pb-Sn phases) and solid phase inclusions (strengthened phase, Al2Cu). The mechanical properties of ultimate tensile strength (σu), Brinell hardness (HB), and elongation to failure (δ) were used as control responses for constructing the ANN network. The constructed network was optimized by attempting different network architecture designs to reach minimal errors. Besides the excellent tribological characteristics of the designed set of alloys, soft inclusions based on Sn and Pb and solid-phase Cu inclusions fulfilled the necessary level of mechanical properties for anti-friction alloys; the maximum mechanical properties reached were: σu = 197 ± 7 MPa, HB = 77 ± 4, and δ = 20.3 ± 1.0%. The optimal ANN architecture with the lowest errors (correlation coefficient (R) = 0.94, root mean square error (RMSE) = 3.5, and average actual relative error (AARE) = 1.0%) had two hidden layers with 20 neurons. The model was validated by additional experiments, and the characteristics of the new alloys were accurately predicted with a low level of errors: R ≥ 0.97, RMSE = 1–2.65, and AARE ˂ 10%. [ABSTRACT FROM AUTHOR]

This study has compared the performance of cryogenically processed EN 52 Silchrome valve steel with untreated material. After completing the standard heat treatment process, EN 52 steel material specimens are subjected to a deep cryogenic process with varying soaking temperatures. The parameters of the deep cryogenic procedure were changed to find the best wear qualities. The key features of valve steel, such as microstructure, mechanical, and wear behaviour are evaluated by conducting a test study. The evolution of wear mechanisms after enhancing qualities of EN 52 steel is studied using scanning electron microscopy. The mechanical and wear behaviour improved due to factors such as fine carbide precipitation, conversion of residual austenite, and carbide refining formed after cryogenic treatment. With a maximum reduction in wear rate of up to 45%, the deep cryogenic treatment of EN 52 steel with a soaking temperature of −140 °C was the ideal parameter. All three cryo-treated samples had better properties than the untreated EN 52 valve steel. [ABSTRACT FROM AUTHOR]

The Taguchi-Grey relational method was used to determine the optimal setting of wear behavior of Al–Si–Mg alloy reinforced with synthesis carbon nanotube derived from rice husk (CNTs-derived RH) and periwinkle shell nanoparticle (PWSnp) nanocomposites for friction material. The applied load, sliding speed, sliding time, and abrasive mesh were the wear parameters, and coefficient of friction and wear rate were used in the multi-response for the study. The minimum coefficient of friction and wear rate were obtained at the optimal parameter of applied load (20 N), sliding speed (1.5 m/s), sliding time (60 min), and abrasive mesh (1000 grit). The coefficient of friction rises as applied load increases and decreased with an increase in sliding speed, sliding time, and abrasive mesh. The Taguchi-Grey approach can be used in multi-response optimization of Al–Si–Mg/CNTs-derived RH and PWSnp nanocomposites since the experimental values are within the limit of predicted values. Hybrid nanocomposites of A356 alloy 0.5 wt% CNTs derived from RH and PWSnp can be used in brake applications. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of two heat treatments on the microstructure, the tensile and the fatigue properties of a powder metallurgy tool steel that has undergone two heat treatments: quenching and multiple tempering (conventional for powder metallurgy tool steel), and quenching and multiple tempering with an intermediate cryogenic step at −80 °C (new solution). The findings of the research indicated that the new heat treatment promotes the development of a homogeneous distribution of carbides in the martensitic matrix, with an increase of about 10% in tensile strength and about 7% in elongation to failure. This combination of exceptional strength with a high degree of toughness leads to an improvement in the fatigue behaviour of the steel, which exhibits a higher unnotched and notched fatigue strength (about 15% and 25% respectively) and a lower fatigue notch factor (about 15%) compared to conventionally heat-treated steel. These results highlight that the powder metallurgy tool steel, with the new heat treatment, could be a viable option for the production not only of tools and dies, but also for high-performance automotive components, including even those with complex geometries, such as camshafts or crankshafts. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of TiB2 on the tribological properties of CuSn10Bi3 bimetallic bearing materials. CuSn10Bi3 samples with different contents of TiB2 were fabricated by powder sintering technology. Their metallographic structures and tribological characteristics under different working conditions were analyzed and compared. The results showed that TiB2 refined the copper alloy grains, passivated the grain boundary edges, and reduced the surface porosity of the sample. When the content of TiB2 was 1%, the wear rate under different oil conditions (oil-rich, oilless, and dry friction) was reduced by 42–95%. The sharp decrease in the wear rate was attributed to the enhancement of the micrograin structure of the copper alloy matrix material by TiB2 hard particles with antiwear properties and the high hardness and high wear resistance of TiB2. The wear tracks were analyzed using scanning electron microscopy and energy-dispersive spectroscopy, and it was concluded that the addition of TiB2 enhanced the wear resistance. [ABSTRACT FROM AUTHOR]

This study investigated the effects of Deep Cryogenic Treatment (DCT) on machinability, hardness, and microstructure in dry turning process of AISI 4140 (48-51 HRc) tempered steels with ceramic cutting tools on the surface roughness (Ra). DCT process of steels has shown significant improvement in their mechanical properties. In this context, experiments were made with Taguchi L16 method and optimum values were determined. Three different values for each control factors as: different heat treated samples, cutting speeds (160, 200, 240, 280 m/min), feed rates (0.08, 0.12, 0.16, 0.20 mm/rev) were selected. As a result, the lowest Ra value was found to be 0.159 µm for the DCTT36 sample at a cutting speed of 240 m/min, a feed rate of 0.08 mm/rev. The optimum Ra value was the lowest for the DCTT36 sample compared to the other samples as 0.206 µm. The hardness values of the micro and macro were highest for the DCTT36 sample. Microstructural point of view Scanning Electron Microscopy (SEM) point of view, the DCCT36 sample showed that best results owing to its homogeneity. It was concluded that lower Ra values can be obtained with ceramic cutting tool in dry turning experiments according to the studies in the literature review. It is thought to be preferred as an alternative to cylindrical grinding process due to lower cost. [ABSTRACT FROM AUTHOR]

In the current study, the effect of different B4C additions (0, 2.5, 5, and 10 wt%) on the microstructural, solidification behavior, mechanical, and tribological properties of Al-20%Mg2Si composite were studied by means of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Vickers hardness, tensile, and dry sliding wear tests. The cooling curve thermal analysis (CCTA) approach was utilized to monitor the influence of B4C particles on the solidification behavior of Al-20%Mg2Si composite. The results revealed that the addition of B4C particles up to 10 wt% reduced the nucleation temperature (TN) and growth temperature (TG) of the primary Mg2Si phase. Moreover, the proper amount of B4C added to Al-20%Mg2Si composite has a significant effect on the microstructural alteration, mechanical, and tribological properties of the composite. The mean size of primary Mg2Si in Al-Mg2Si composite was 47 μm, in which with the addition of 5 wt% B4C, the particle size decreased to 33 μm. The highest UTS (217 MPa) and El% (7%) was achieved in Al-20%Mg2Si-5%B4C hybrid composite. The cast Al-20%Mg2Si composite revealed the brittle mode of fracture with some cleavage characterization, in which with the addition of 5%B4C, the fracture mode altered to a more ductile fracture. The wear results revealed that the Al-20%Mg2Si-5%B4C hybrid composite has the highest wear resistance with the lowest wear rate (0.46 mm3/Km) and friction coefficient (µ = 0.52) under 20 N applied load compared to other fabricated composites with mild abrasion as the governed wear mechanism. [ABSTRACT FROM AUTHOR]

Cyclic cryogenic treatment, a major cycle accompanied by zero or more subsidiary cycles, was conducted on the hardened 42CrMo steel using orthogonal design method to investigate the effect of different parameters (cryogenic temperature, holding time, and cycles number) of cryogenic treatment on wear resistance and impact toughness of the steel. Range analysis was performed to obtain the influencing order of the three parameters and their optimum values. The results show that after cryogenic treatment, the steel exhibits higher wear resistance and impact toughness, whereas no significant change in hardness. For wear resistance, the influencing order of parameters is cryogenic temperature, holding time, and cycles number, and the optimum values of the parameters are −160°C, 24 h and two cycles, respectively. For impact toughness, the influencing order of parameters is cryogenic temperature, cycles number, and holding time, and the optimum values are −120°C, 24 h and three cycles, respectively. The wear topography and fracture topography were examined using scanning electronic microscopy (SEM) to investigate the wear mechanism and fracture mechanism of the steel after cryogenic treatment, respectively. The results show that after cryogenic treatment, the wear mechanism is the combination of abrasive wear and adhesive wear with oxidative wear, and the fracture mechanism is a quasicleavage fracture. The microstructure was also examined by SEM to investigate the influencing mechanism of cryogenic treatment for improving wear resistance and impact toughness of the steel. It suggests that more precipitation of fine carbides dispersively distributed in the matrix is responsible for the beneficial effect of cryogenic treatment on wear resistance and impact toughness of the steel. [ABSTRACT FROM AUTHOR]

he purpose of the current metallurgical work is to analyse the mechanical property alteration and microstructure evaluation of Al6061 hybrid composites by age hardening treatment using three different aging temperatures. Al6061 hybrid composites reinforced with B4C and SiC particles have been manufactured using two-stage stir casting method. The optical micrographs were analysed for the dispersivity of the reinforcements in the matrix. To assure the type of reinforcements in the matrix SEM analysis was carried out. It was found that during solutionising and aging at 100, 150 and 200°C, presence of SiC and B4C particles in the hybrid Al6061 matrix composites showed substantial improvement in hardness compared to that of the base alloy. Transmission electron microscopy (TEM) was used to identify the intermetallic phases, morphology and orientation of the particulates responsible for the peak aging behaviour. It was observed that while aging at 100°C excellent peak hardness values are observed in the composite group with well-distributed fine precipitates of Mg2Si along grain boundaries as well as within the grains. The composition Al6061-3B3S composites showed an additional secondary intermetallic phase viz., α-Al12Fe3SiMg along with Mg2Si, which is responsible for the superior aging behaviour over other compositions. [ABSTRACT FROM AUTHOR]

The consequences of key process parameters of cryogenic treatment (i.e. holding time and temperature) on the average coefficient of friction and wear rate in dry sliding condition at different level of load (60, 80, 100, 120 & 140 N) and sliding velocity (0.628, 0.942, 1.257, 1.571 & 1.885 m/s) have been explored through cubic regression mathematical modeling technique. An average error of 1% and 9.9% has been observed in the experimental and model given values for coefficient of friction and wear rate. Mathematical model equation capability is within the range of 95% confidence level. Moreover, desirability function approach has been employed to find out the process parameter to have lower wear resistance. Worn out samples have been examined with field emission scanning electron microscope (FESEM) and reveals that the operative mechanism for wear is delaminating and rupturing of matrix. [ABSTRACT FROM AUTHOR]

This paper compares some of the key machinability aspects acquired during milling of Ti6Al4V titanium alloy with uncoated and coated cryogenically treated end mills. Tool wear, coefficient of friction, cutting force, and chip morphology were the major criteria considered. Ti6Al4Vis one of the titanium alloys that are widely used in aerospace and biomedical applications; however, it has a poor machinability and tribological properties. To evaluate the performance of cryogenically treated end mills, milling operations using a force dynamometer and dry sliding tests were conducted. The milling operations were conducted with a cutting speed of 90 m/min, a feed rate of 0.11 mm/tooth, a 1-mm axial depth of cut, and a 10-mm radial depth of cut under dry cutting conditions. The dry sliding tests were conducted using a tribometer with a ball-on-disk geometry under 10 N load and a speed of 5 cm/s. The milling test results showed that flank wear, chipping, and tool breakage were the wear mechanisms of the end mills. The cutting force measurements and the dry sliding tests showed that the cutting force and friction force values decreased when the cryogenic treatment time increased. As a result of the study, tools treated cryogenically for 36 h showed the best performance for the cutting force, friction force, and tool wear criteria. These improvements were characterized with hardness, fracture toughness, scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses. [ABSTRACT FROM AUTHOR]

Experimental study of the effect of wear parameters on the wear behaviour of A356 alloy reinforced with cow horn particles (CHp) produced by spark plasma sintering was investigated. Experiments were conducted based on the plan of experiments generated through Taguchi's (L9) technique. Tribometer was used for the wear test and Scanning electron microscope was used to analyse the worn scar of the samples. The results shows that, A356 alloy reinforced with CHp exhibited better dry sliding wear resistance than the unreinforced alloy. Wear rate decreased as the amount of CHp reinforcement increased in the matrix. It was found that, the optimum level of the factors with minimized the wear loss were obtained at: wt%CHp (20%), applied load (10 N), sliding velocity (3 m/s) and sliding distance (2000m). It can be seen that the wear track of the sample are (D = 0.81 andL = 42.85 mm) and (D = 0.54 and L = 27.03 mm) for A356alloy and composites at optimum condition respectively. The results showed that the addition of cow horn particles as reinforcing materials in A356 alloy composites increased the wear resistance of the composites greatly. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to investigate the microstructure, hardness and tribological properties of hypoeutectic (Al-7Si) matrix reinforced with fixed quantities of 3 Wt.% graphite (Gr) and x Wt.% SiCp (x = 3, 6 and 9) hybrid composites. Design/methodology/approach – The composites were fabricated by stir cast technique. The microstructure, hardness and tribological measurements were carried out on the base alloy and composites. The tribological investigation was carried out on pin-on-disc wear testing machine under dry sliding condition. Findings – The wear rate decreases with the increase of SiCp into A356-3Gr composites. The composite containing A356-9SiCp-3Gr had better hardness and good wear resistance compared to the base alloy. Scanning electron microscope (SEM) and electro dispersive spectrometry (EDS) images were used to study the reinforcement distribution and worn-out surface of the specimens. Originality/value – The present paper brings out a clear picture of the various events that take place under the worn-out surfaces leading to the generation of mechanical mixed layer. [ABSTRACT FROM AUTHOR]

In this study, the effects of deep cryogenic treatment (DCT) on the wear resistance of AISI 52100 bearing steel were investigated. For this purpose, a number of bearing steel samples were held for different times (12, 24, 36, 48, 60 h) at deep cryogenic temperatures (−145 °C). The wear experiments were carried out in a ball-disk arrangement, by applying loads of 10 and 20 N and a sliding velocity of 0.15 m/s. After conducting the experimental studies, 36 h was found to be the optimal holding time. At this holding time, the wear rate and friction coefficient were decreased, while the hardness reached to maximum values. It was observed that DCT led to significant microstructural changes, which resulted in improved tribological properties. [ABSTRACT FROM AUTHOR]

The present investigation focused on abrasive waterjet cutting (AWJC) of natural fibre reinforced nano clay filled polyester composites with the objectives of maximizing material removal rate (MRR) and minimizing the kerf taper (KT) and surface roughness (Ra). The influence of nano clay addition, traverse speed (TS), jet pressure (JP) and stand-off distance (SOD) on the AWJC characteristics of fabricated composite laminates are investigated. The natural fibre reinforced composite (NFRC) laminates are fabricated through hand lay-up technique through varying the wt% of nano clay fillers (0, 1 and 2). The AWJC experiments are planned and rigorous experiments were performed by adopting box-behnken design approach. The relative consequence of process variables on response features and quadratic regression models were assessed through analysis of variance (ANOVA). Further, multiple response optimization is carried out using statistical desirability technique to enhance the cut quality characteristics. The optimal AWJC parameters such as JP of 316.24 MPa, SOD of 2 mm and TS of 304.24 mm/min with 1.15 wt% of nano clay addition are determined. Microstructure of cut surface is examined to ascertain the morphological behaviour of AWJC surfaces with different processing conditions. [ABSTRACT FROM AUTHOR]

In the present investigation, the microstructural and mechanical properties study of A356 alloy have been discussed. The microstructural aspect of cast A356 alloy employed in the present study is strongly dependent on the grain refinement (Ti and B) and modification (Sr). The mechanical properties such as PS, UTS, %E, %R, YM and VHN have been investigated. This paper deals with the combined effect of grain refinement and modification, which improves the overall mechanical properties of the alloy. It is also a well-known fact that the mechanical properties of cast A356 alloy were improved by subjecting suitable melt treatment such as grain refinement, modification and mould vibration, etc. The quality of castings and their properties can be achieved by refining of α-Al dendrites in A356 alloy by means of the addition of elements such as Ti and B which reduces the size of α-Al dendrites, which otherwise solidifies with coarse columnar α-Al dendritic structure. In addition, modification is normally adopted to achieve improved mechanical properties. Metallographic studies reveal that the structure changes from coarse columnar dendrites to fine equiaxed ones on the addition of grain refiner and further, plate like eutectic silicon to fine particles on addition of 0.20% of Al-10Sr modifier. The present result shows that a reduction in the size of α-Al dendrites, modification of eutectic Si and improvement in the mechanical properties were observed with the addition of grain refiner Al-3Ti, Al-3B and modifier Al-10Sr either individual addition or in combination. The change in the microstructure from coarse columnar α-Al dendrites to fine equiaxed dendrites and plate like eutectic silicon to rounded particles leads to improved mechanical properties. [ABSTRACT FROM AUTHOR]

The growing demand for composite materials with improved properties is attracting a lot of attention from industries such as automotive, aerospace, military, aviation, and other manufacturing. Aluminium metal matrix composites (AMMCs), with various reinforcements such as continuous/discontinuous fibers, whiskers, and particulates, have captured the attention due to their superior tribological, mechanical, and microstructural characteristics as compared to bare Al alloy. AMMCs have undergone extensive research and development with different reinforcements in order to obtain the materials with the desired characteristics. In this paper, we present a review on AMMCs produced through stir casting routes. This review focuses on the following aspects: (i) different reinforcing materials in AMMCs; (ii) microstructural study of reinforced metal matrix composites (MMCs) through stir casting. Both reinforcing micro- and nanoparticles are focused. Micro- and nanoreinforced AMMCs have the attractive properties of combination such asthe low-weight-to-high-strength rati and, low density; (iii) various tribological and mechanical properties with the consideration of different input parameters; (iv) outlook and perspective. [ABSTRACT FROM AUTHOR]

Cryogenic treatment is a supplemental structural and mechanical properties refinement process to conventional heat treatment processes, quenching, and tempering. Cryogenic treatment encourages the improvement of material properties and durability by means of microstructural alteration comprising phase transfer, particle size, and distribution. These effects are almost permanent and irreversible; furthermore, cryogenic treatment is recognized as an eco-friendly, nontoxic, and nonexplosive process. In addition, to encourage the application of sustainable techniques in mechanical and manufacturing engineering and to improve productivity in current competitive markets, cryo-treatment can be considered as a promising process. However, while improvements in the properties of materials after cryogenic treatment are discussed by the majority of reported studies, the correlation between microstructural alteration and mechanical properties are unclear, and sometimes the conducted investigations are contradictory with each other. These contradictions provide different approaches to perform and combine cryogenic treatment with pre-and post-processing. The present literature survey, mainly focused on the last decade, is aimed to address the effects of cryogenic treatment on microstructural alteration and to correlate these changes with mechanical property variations as a consequence of cryo-processing. The conclusion of the current review discusses the development and outlines the trends for the future research in this field. [ABSTRACT FROM AUTHOR]

Through a combination of 3D representative volume element (RVE) and the metallo-thermo-mechanical coupling finite element (FE) analysis, a multiscale model was established to explore the localized characteristics of microstructure and stress evolution during deep cryogenic treatment (DCT). The results suggest that after cooling to near −160 °C, the largest intensity of martensite is formed, but the retained austenite cannot be eliminated completely until the end of DCT. The driving force for the precipitation of fine and uniform carbides during DCT is provided by the competition between the thermal and phase transformation stresses. Compared with the thermal stress, the phase transformation stress during DCT plays a more significant role. At the interface between retained austenite and martensite, a reduction of around 15.5% retained austenite even induces an obvious increase in the phase transformation stress about 1100 MPa. During DCT, the maximum effective stress in RVE even exceeds 1000 MPa, which may provide a required driving force for the precipitation of fine and homogeneously distributed carbide particles during DCT. [ABSTRACT FROM AUTHOR]

The 2024 nanocomposite reinforced with Al2O3 nanoparticles was fabricated by the ultrasonic assisted semisolid stirring (UASS) method and rheoformed into a cylinder component. Microstructure, mechanical properties, and wear behavior of the rheoformed composite components were investigated. The results showed that the composite components with complete filling status and a good surface were rheoformed successfully. The deformation of semisolid slurries was mainly dominated by flow of liquid incorporating solid grains (FLS), sliding between solid grains (SSG), and plastic deformation of solid grains (PDS). Mechanical properties of the rheoformed composite components were influenced by stirring temperature, stirring time, and volume fraction of Al2O3 nanoparticles. The optimal ultimate tensile strength (UTS) of 358 MPa and YS of 245 MPa were obtained at the bottom of the rheoformed composite components after a 25-min stirring of composite semisolid slurry with 5% Al2O3 nanoparticles at 620 °C. Enhancement of mechanical properties was attributed to high density dislocations and dislocation tangles and uniform dispersed Al2O3 nanoparticles in the aluminum matrix. Natural ageing led to the occurrence of needle-like Al2CuMg phase and short-rod-like Al2Cu phase. UTS of 417 MPa and YS of 328 MPa of the rheoformed composite components were achieved after T6 heat treatment. Improvement of mechanical properties is due to the more precipitated needle-like Al2CuMg phase and short-rod-like Al2Cu phase. Wear resistance of the rheoformed composite components was higher than that of the rheoformed matrix component. Wear resistance of the rheoformed composite component increased with an increase in Al2O3 nanoparticles from 1% to 7%. A slight decrease in wear rate resulted from 10% Al2O3 nanoparticles due to greater agglomeration of Al2O3 nanoparticles. A combination mechanism of adhesion and delamination was determined according to worn surface morphology. [ABSTRACT FROM AUTHOR]

Natural fiber composite laminates are nowadays used in structural application such as aerospace, automobile and in sports goods because of their high strength to weight ratio and renewability. Hence the study of mechanical behaviors of natural fiber composites is very important in using these composite laminates for such specific applications. This project aims at identifying the mechanical properties of hybrid natural Jute/Kenaf fiber. The major drawbacks in natural fiber are its Resin incompatibility. Surface treatment of fiber is made to improve the interfacial bonding between the fiber and resin and to reduce the moisture absorption. Laminates are fabricated using Hand lay-up technique. Mechanical properties such as tensile, flexural, and Impact test for jute/kenaf hybrid laminates were obtained. Specimen preparation and Mechanical property testing were carried out as per ASTM standards. Micro structures of the different layer of hybrid specimens are scanned by the Scanning Electron Microscope. [ABSTRACT FROM AUTHOR]