To determine the relationships between operating conditions and tribological properties of Zn-30Al-3Cu alloy, its wear characteristics were investigated at wide ranges of oil flow rate, pressure and sliding velocity using a block-on-disk type test apparatus. The results are compared to those of SAE 660 leaded bearing bronze. Wear loss of these materials increased with sliding distance, pressure and sliding velocity, but decreased slightly with oil flow rate. The relationships between operating conditions and lubricated wear properties of Zn-30Al-3Cu alloy were determined by nonlinear regression analysis of the experimental data. Lubricated wear behavior of the zinc-based alloy was discussed in terms its microstructure and mechanical properties, and test conditions.

The Tungsten Inert Gas (TIG) welding processes one of the prevalent methods used for welding aluminum alloys. TIG welding is most commonly used due to its superiority in welding less dense materials. The most prevalent issues encountered with TIG welding aluminium alloys are porosity creation and cracking due to solidification, both of which result in lower mechanical properties. Because of the metal’s susceptibility to heat input, this occurs. The current work is the result of a desire to improve the mechanical properties of dissimilar aluminium metals: AA5052-H32 & AA5083-H111. The process parameters of TIG welding are optimized towards eliminating the previously discussed failure scenarios. Various optimization techniques exist towards obtaining optimizing processes such as Response Surface Methodology (RSM), Genetic Algorithm (GA), Artificial Neutral Network (ANN), Flower pollination algorithm, Taguchi method etc, The Taguchi method was chosen for the optimization of process parameters due to its inherent nature of solving problems of singular variance. The optimal parameters combination was determined i.e. welding current at 170 A, filler rod diameter 2.4 mm and Gas flow rate of 11 lpm. The optimized input parameter was used to TIG weld the confirmation specimen which are further investigated for mechanical and metallurgical characterizations. The parameters were optimized and the results indicate that the input current was found to be the most contributing towards improving mechanical properties over all the process parameters.

In this study, a hybrid surface composite of AA5083/SiC-Gr was produced by Friction Stir Processing (FSP). Reinforcement material each in 50:50 proportion was filled in the base matrix using holes method. Three different hybrid reinforcement volumes of 301.6 mm ³, 452.4 mm ³, and 603.2 mm ³ were prepared for surface composite. Optical and Scanning Electron Microscopy was used to check the quality of the prepared surface composite and homogeneous distribution of reinforcement was observed in the images. It was observed that due to better uniform distribution of reinforcement particles during 3 pass FSP, specimens with 301.6 mm ^3/ reinforcement volume showed enhanced microhardness and wear properties in comparison with the other specimens. Keywords: Surface Composites; Multi-pass; Friction Stir Processing; Reinforcement; Hybrid Composite

In this study, Hydroxyapatite (HAp) is extracted from the Rihu fish scales which are generally dumped as garbage. The aluminium composite was fabricated through the powder metallurgy technique by reinforcing HAp (0, 5, 10 and 15 wt%) as a reinforcement. The fabricated samples were sintered through microwave sintering at 530℃ for 15 min under an argon gas environment. The fabricated composites were subjected to X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis to confirm the constituting elements and to describe the reinforcement dispersion in the matrix. Uniform reinforcement dispersion was observed for the composite reinforces with 5%HAp, 10%HAp particles. The mechanical characterization results reveal that the Al-10% HAp composite exhibits a microhardness value of 123 ± 3 Hv and maximum ultimate tensile strength of 263 ± 10 MPa and 299 ± 9 MPa compression strength was obtained due to the presence of a strong bond among the aluminium and HAp particles.

The copper and copper alloys’ ingots have been subjected to structural observation in order to estimate the Peclet Number at which these ingots were solidifying. It was stated that the formation of columnar structure within the ingots occurred at a high Peclet Number, higher than the threshold value of this parameter, Pe = 500. The formulated relationships of the Growth Law correspond to a high Peclet Number due to application of the adequate development in series of the Ivantsov’s function. The Growth Law has been developed on the basis of the definition of the wavelength of perturbation which leads to the dispersion of the planar s/l interface. New definition of the index of stability connected with the behavior of solute concentration at the s/l interface has been delivered. The current definition is related to non-equilibrium solidification. The index can be easily calculated using some parameters delivered by a given Cu-X phase diagram. Physical meaning of the formulated Growth Law has also been presented.

The main focus of this work was the effect of chemical alkaline treatment on Himalayan nettle fibre extraction and the characterization analysis of surface-modified nettle fibre. Nettle fibre is an eco-friendly material naturally grown in the Himalayan hills of India, and it is replacing man-made fibres. The fibres are primarily bound to each other and, in turn, to the core of the plant with pectin, lignin, and gums, which begin to break down through fungal, bacterial, enzymes and chemical treatment action. The stem from the nettle plant is fibrous and has a high-quality fibre to develop nettle yarn, which is utilized to make clothes and handicrafts, mostly aimed at generating livelihood opportunities for the rural tribe’s people. This method of extraction is an effective chemical treatment for enhancing interfacial adhesion between nettle fibres and the epoxy, which is one of the significant challenges to their usage in textiles. In this paper, nettle fibres treated with chemicals such as 1% sodium hydroxide (NaOH), 0.5% sodium sulphite (Na2SO3), 0.05% ethylenediaminetetraacetic acid (EDTA), and 2% acetic acid (CH3COOH). The impact of bacterial and chemical treatments on nettle fibre and untreated nettle fibre was characterized by Fourier transform infrared spectroscopy (FTIR) analysis, which is used to study the functional elements, Scanning electron microscopy (SEM) images revealed that there is a fibre breaking mechanism and cross-section of yarn twist formation, physical and mechanical characteristics were then determined for fibre tensile strength, fibre length, Young’s modulus, elongation break, fineness, and moisture content.

This study aimed to investigate the effect of different coating processes on interlayer coating using ProCAST software and identify the preferred coating process so as to prepare an EH40/2205 composite plate with a coating interlayer of Ni-5 Fe-15 Co (wt.%) displaying good performance. The preparation and characterization tests were conducted to analyze the interlayer coating, the diffusion of elements at the bonding interface and the mechanical properties of the hot-rolled composite plate. The results showed that the coating rate increased linearly with an increase in the initial coating temperature, pressure difference and the width ratio of the suction layer. The interlayer coating was complete under the guidance of optimized process parameters, and the test results and simulations confirmed each other. The coated interlayer successfully blocked the diffusion of elements between the bonding surfaces. The tensile strength of the rolled composite plate was 580 MPa, which met the needs of the project. The tensile shear fracture occurred at EH40, which proved that the plate was well bonded.

The tensile properties and microstructures of ZL114A alloy component with a complex shape are investigated at room temperature and 200°C, using the tensile tests, scanning electron microscopy and electron backscattering diffraction. Both thin wall and thick structure exhibit excellent properties, of which max ultimate tensile strength and elongation at break reach 314 MPa and 2.5% at room temperature, respectively. The ultimate tensile strengths of thin wall are 40 MPa and 25 MPa greater than those of thick structure at room temperature and 200°C, respectively. Moreover, the eutectic Si phases of thin wall exhibit a predominantly spherical morphology while of the morphology of thick structure are rod-like, resulting in the different mechanical properties between thin wall and thick structure. The fracture morphologies of thin wall and thick structure are studied to explain the difference in performance between thin wall and thick structure.

The effect of aging time at 850°C for 300 s, 600 s, 1800 s, and 84600 s on the microstructural evolution and corrosion resistance of 2205 duplex stainless steel (DSS) was studied after cold rolling up to 60% of reduction. X-ray diffraction, scanning electron and transmission electron microscopy were used for microstructural characterization. The corrosion behavior was studied by cyclic potentiodynamic polarization (CPP) and electrochemical impedance technique (EIS) in 3.5% NaCl solution and the susceptibility to sensitization was investigated through the double loop electrochemical potentiodynamic reactivation (DL-EPR) test in 0.5 M H2SO4 + 0.1 M NaCl + 0.002 M KSCN solution. After cold working, increasing aging time led to an increase in sigma phase precipitation and a decrease in pitting corrosion resistance. However, the ultrafine microstructure had a beneficial influence on the self-healing effect in Cr and Mo depleted areas with the increasing of aging time, resulting in higher passivation ability. The DSS 2205 type was not susceptible to intergranular corrosion for the aged conditions applied.

Present study describes about the effect of coolant water flow rate and coolant water temperature underside cooling slope on structural characteristics of casted AZ91 Mg alloy. Here, over the cooling slope, hot melt flows from top to bottom. Additionally, under the cooling slope, coolant water flows from bottom to top. Slurry gets obtained at bottom of cooling slope by pouring AZ91 Mg melt from top of the slope. Coolant water flow rate with coolant water temperature underside cooling slope warrant necessary solidification and shear to obtain AZ91 Mg slurry. Specifically, slurry at 5 different coolant water flow rates (4, 6, 8, 10, 12 lpm) and at 5 different coolant water temperatures (15, 20, 25, 30, 35°C) underside cooling slope are delivered inside metal mould. Modest coolant water flow rate of 8 lpm with coolant water temperature of 25°C (underside cooling slope) results fairly modest solidification that would enormously contribute towards enhanced structural characteristics. As, quite smaller/bigger coolant water flow rate/temperature underside cooling slope would reason shearing that causes inferior structural characteristics. Ultimately, favoured microstructure was realized at 8 lpm coolant water flow rate and 25°C coolant water temperature underside cooling slope with grain size, shape factor, primary α-phase fraction and grain density of 63 µm, 0.71, 0.68 and 198, respectively. Correspondingly, superior mechanical properties was realized at 8 lpm coolant water flow rate and 25°C coolant water temperature underside cooling slope with tensile strength, elongation, yield strength and hardness of 250 MPa, 8%, 192 MPa and 80 HV, respectively.

This paper presents the results of research into the cross wedge rolling (CWR) process of axle forgings. The presented results concern the parallel rolling process with two wedges. The use of two parallel wedges is aimed at shortening the tool length (increasing productivity) and reducing the values of wedge opening angles and increasing the forming angles, so that the condition 0.04 ≤ tgαtgβ ≤ 0.08 is maintained to guarantee the highest quality forgings. The article analyses the influence of the design of the double wedge tool on the geometric correctness of the forgings obtained, the value of the failure criterion and the force parameters of the process. The results obtained show that the use of multi wedge tools improves rolling conditions by increasing productivity and reducing the tendency of the material to crack with appropriately selected tool parameters.

Processing of metal alloys in semi-solid state is a way of producing many near net-shape parts and nowadays is commercially successful. Particular behaviour of alloys in the partially liquid state, having non-dendritic microstructure, is a base for thixoforming processing. Processing materials in the semi-solid state concerns alloys with relatively wide solidification range. Thermodynamic modelling can be used as a one of a potential tools that allow to identify alloys with proper temperature range. It means that the key feature of alloys suitable for thixoforming is a widely enough melting range, allowing for precise control of material temperature. The data gathered from thermodynamics calculations can also pay off in the industrial thixoforming processes design. The goal of this paper is to identify copper alloys which can be successfully shaped in the semi-solid state. Apart to thermodynamic calculations, the observations on high temperature microscope was carried out. During experiments the solidus, liquidus and also deformation temperatures can be determined. An experimental work allows confirming results obtained within the confines of thermodynamic calculations and firstly to determine the deformation temperatures which are the optimal for shaping processes. The basic achievement of this work is an identification of copper alloy groups possible for shaping in the semi-solid state. At the first part of the paper, the basic criteria of suitable alloys were described. Next, both the solid fraction curves for copper alloys with different alloying elements using ProCAST software and the phase diagrams were determined to identify the solidification temperature ranges of these alloys. In the second part of these paper, the identification of the deformation temperatures was carried out with use of high temperature microscope observation.

The as-cast microstructure of ductile cast iron (DI) was investigated using light microscopy (LM) and SEM techniques. Further the influence of hot plastic extrusion at 1000°C with plastic strain in the range of 20-60-80% on the transformation of the as-cast microstructure and on the mechanical properties was studied. Besides this, the microstructure of DI subjected to hot extrusion after the fracture of the corresponding samples induced by compression tests was thoroughly investigated. It was found that compression had a dramatic influence on a shear deformation and hence shear fracture of the compressed samples. It was shown that the shear fracture of the hot deformed ductile iron is accompanied by the occurrence of a narrow zone of severe plastic deformation. The fracture surfaces of the extruded samples subjected to the tensile tests and the compression tests were examined.

Currently, one of the main challenges of civil engineering and science materials engineers is to develop a sustainable substitute for Ordinary Portland Cement. While the most promising solution is provided by the geopolymerisation technology, most of the studied geopolymers are based on natural raw materials (kaolin). The metakaolin is mainly preferred because of its rapid rate of dissolution in the activator solution, easy control of the Si/Al ratio, and white color. However, its high cost prevents it from being widely used in geopolymer composites or other materials that can become an industrial alternative for Ordinary Portland Cement. Several studies have shown that geopolymers with good performance can also be obtained from secondary raw materials (industrial wastes such as coal ash or slag). This explains why countries with rapidly developing economies are so interested in this technology. These countries have significant amounts of industrial waste and lack a well-developed recycling infrastructure. Therefore, the use of these by-products for geopolymers manufacturing could solve a waste problem while simultaneously lowering virgin raw material consumption. This study evaluates the effect of replacing different amounts of coal ash with sand on the microstructure of sintered geopolymers. Accordingly, scanning electron microscopy and energy dispersive X-ray analysis were involved to highlight the morphological particularities of room-cured and sintered geopolymers.

The coarse-grained heat-affected zone specimens of X80 pipeline steel were produced by welding thermal simulation under different heat inputs of 10, 30, and 55 kJ/cm to study the effects of heat input on microstructure evolution and corrosion characterization. The corrosion resistance of coarse-grained heat-affected zones was poorer than that of base metal due to less homogenous in the former. For 10 kJ/cm coarse-grained heat-affected zone, the corrosion resistance was poorer than the others due to the more adsorption hydrogen around the needle-like martensite/austenite constituents and greater galvanic driving force between the needle-like martensite/austenite constituents and ferrite. In carbonate/bicarbonate solution, better corrosion resistance for coarse-grained heat-affected zones was obtained when the heat input is 30 kJ/cm, which can be attributed to the severe coarse martensite/austenite constituents for 55 kJ/cm coarse-grained heat-affected zone. In the H2S environment, the better corrosion resistance for coarse-grained heat-affected zone was obtained when the heat input is 55 kJ/cm, which can be attributed to the protective effect of corrosion products. In addition, the high content of M/A constituents for 30 kJ/cm CGHAZ was good for hydrogen adsorption, which was adverse to the corrosion resistance in acid environments.

In this study, the microstructures and mechanical properties of X70 pipeline steels produced with varying Mo contents, accelerated cooling rate and intermediate slab blank thickness are systematically investigated. Results showed that the microstructures and mechanical properties of the X70 pipeline steels were strongly affected by Mo addition. The pearlite and proeutectoid ferrite formation is obviously inhibited in containing-Mo steel and the acicular ferrite (AF) is obtained in a wide range of cooling rates. With the increasing the cooling rates, the AF constituent amount increases. The grains can be refined by increasing the thickness of intermediate slab for enhancing the cumulative reduction rates, and meanwhile increase the number density of precipitates. It was proved by simulation and industrial trials that the low-alloy X70 pipeline steels can be produced increasing cooling rates and the thickness of intermediate slab without strength and toughness degradation which also reduce alloy cost.

In this work, a comparative study on the ballistic behaviour of friction stir processed AL6061 targets had been made. Base Metal AL6061 (BM) plates with 25 mm thickness were friction stir processed by adding Multi Walled Carbon Nano Tubes (MWCNT) and Graphene (G), producing AL6061-MWCNT and AL6061-G surface composites. Optical microscopy and microhardness test on BM, AL6061-MWCNT and AL6061-G samples were performed as per the standard procedure. It was noticed that uniform dispersion of ceramic particles and refined grains were obtained for the friction stir processed surface composites. From the microhardness test, it was perceived that friction stir processing had induced strengthening of surface composites, hence increasing the microhardness of AL6061-MWCNT and AL6061-G by ~60.3% and ~73.6% respectively. Also, ballistic experiments were conducted at 680±10 m/s by impacting Ø7.62×51 mm projectiles. AL6063 backing plates were placed to compare the ballistic behaviours AL6061-MWCNT and AL6061-G targets by depth of penetration. It was noted that the depth of penetration of AL6061-MWCNT and AL6061-G targets were 37.81% and 65.84% lesser than the BM target. Further, from the results of Post ballistic microscopy it was observed that the microstructure near and away from the penetration channel edge looks unchanged in BM target. However, the AL6061-MWCNT and AL6061-G targets showed considerable change in their morphology, by forming Adiabatic Shear Bands.

This study investigates the corrosion characteristics of Q235 steel and 16Mn steel in the sulfur-containing alkaline solution. The composition and the morphology of the corrosion products were analyzed by XPS and SEM respectively. The electrochemical behavior of Q235 steel and 16Mn steel was evaluated by potentiodynamic polarization curve and EIS. The results indicated that the corrosion rate of Q235 steel is greater than 16Mn steel in the early corrosion. Pitting and selective corrosion appeared on the surface of the two steels, and the surface product layer was granular and defective. XPS and EDS indicate that the structurally stable iron oxide is formed on the surface of the two steels. Electrochemical results show the corrosion kinetics of Q235 steel and 16Mn steel are simultaneously controlled by the charge transfer and ion diffusion, and the formation mechanism of corrosion products was clarified.

The aim of this paper is to evaluate the fatigue resistance of austenitic nodular cast iron and to compare it with other types of nodular cast irons. The austenitic nodular cast iron, used for the experiments, was alloyed by 13% nickel and 7% manganese (EN-GJSA-XNiMn13-7) to obtain an austenitic matrix. The microstructure was studied using light metallographic microscopy. Mechanical properties were investigated by tensile test, impact bending test and Brinell hardness test. Fatigue tests were carried out at sinusoidal cyclic push-pull loading at ambient temperature. The results of fatigue tests were compared with the fatigue properties of ferrite-pearlitic nodular cast iron and pearlite-ferritic nodular cast iron. Experimental results show that NiMn-type of austenitic nodular cast iron has lower tensile strength and hardness, but higher elongation and absorbed energy than the compared types of nodular cast iron. However, austenitic nodular cast iron has lower fatigue limit.

2 wt.% TiB2 (mean particle size: 400 nm) reinforced Al 7075 metal matrix composites (MMCs) fabricated through mechanical stirring and ultrasonic agitation integrated squeeze casting process were subjected to electrical discharge machining (EDM) after determining the physical and mechanical properties. EDM was conducted with Cu electrode tools to investigate influence of machining factors, i.e. peak current (IP), pulse on time (TON) and gap voltage (VG) on the tool wear rate (TWR), material removal rate (MRR) and average surface roughness (ASR) of the machined surfaces. All the three responses increased on increasing IP and TON, but reduced on increasing VG. The machined surfaces were studied through scanning electron microscope (SEM). Significance of the EDM parameters on the individual responses were studied using analysis of variance (ANOVA) and regression models for the responses were developed using response surface method (RSM). The responses under consideration were optimized simultaneously using Taguchi embedded weighted principal component analysis (WPCA), which resulted the parametric combination of 4A (current), 100 μs (pulse duration) and 75V (voltage) was the optimal setting for the multi-criteria decision problem. Finally, the result of optimization was validated by conducting some confirmatory experiments.

In this scientific paper it is presented the statistical analysis of the experimental data obtained by the study of the influence of the cutting parameters exerted in end-milling process on the surface roughness. The surface roughness parameter is measured in the cutting feed direction and against it. The parameters of the cutting process, the number of levels and their values were established. Based on these parameters, the research was designed on a complete factorial experiment, randomized with seven blocks. The surface roughness values were measured using a roughness tester. The research method used involved the Romanovski test. The aim of this test was to identify the data affected by aberrant errors, to remove them from the samples and then to repeat the tests for the remaining data strings until all values met the conditions imposed by the test.

In this research, Graphene nanoplatelets (GNP) reinforced epoxy nano composites were fabricated via magnetic stirrer and ultra sonification assisted hand layup method. The impact of different weight percentage of GNP (0, 0.25, 0.50, and 1.0%) on different characteristics of nano composites was evaluated. The microstructure analysis of developed nano composite was determined by Field emission scanning electron microscopy. It was examined that epoxy nano composites containing 0.5 wt.% GNP have the highest tensile, flexural, and impact strength compared to neat epoxy. The reduction in tensile and flexural strength is achieved at 1% of GNP. Adding more nanofiller to a certain limit causes non-uniform dispersion and agglomeration of nanoparticles, which results in a reduction in properties. The 1% GNP reinforced nano composite has the highest value of shore hardness.

The aim of this paper was to analyze the impact of varying zirconium addition on selected properties of AlSi5Cu2Mg alloy. The results of this research showed that zirconium addition in the range of 0.05 to 0.20 wt. % caused a decrease in ultimate tensile strength and yield strength of the experimental alloys after T7 heat treatment, probably due to the formation of primary Al3Zr intermetallic phases. These phases were observed as an individual plates or as a formation of two crossed plate-like phases. Potentiodynamic polarization tests in 3.5% NaCl solution revealed that addition of Zr had a positive effect on thermodynamic corrosion stability of the AlSi5Cu2Mg alloy due to shift of the corrosion potential to a more positive values for all as-cast samples. Addition of Zr in the as-cast alloys improved corrosion kinetics by lowering of corrosion current density.

A simple methodology was used for calculating the equivalent strain values during forming the sample alternately in two mutually perpendicular directions. This method reflects an unexpected material flow out of the nominal deformation zone when forming on the MAXStrain II device. Thus it was possible to perform two temperature variants of the simulation of continuous rolling and cooling of a long product made of steel containing 0.17% C and 0.80% Mn. Increasing the finishing temperature from 900°C to 950°C and decreasing the cooling rate from 10°C/s to 5°C/s led to a decrease in the content of acicular ferrite and bainite and an increase in the mean grain size of proeutectoid ferrite from about 8 µm to 14 µm. The result was a change in the hardness of the material by 15%.