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This work emphasizes the investigation that was carried out on SiC powder reinforced Al–Si–Mg ternary alloy TIG weld composite for analyzing, predicting and optimizing the hardness using Taguchi and Response Surface Methodology (RSM). The study focused on optimizing the TIG welding parameters viz, welding current, welding speed, SiC wt.% and gas flow rate for the hardness of composite using RSM. Samples prepared with varying weight percentages of SiC (8,10,12) were subjected to the TIG welding process using ER5356 filler material. A second-order response surface model for hardness is established from experimental data. The predicted as well as measured values are fairly close by, which specifies that the established model can be well utilized to predict the hardness with 95% confidence intervals. Using such a model, one can achieve significant savings in time and cost. The signal to noise ratio of process parameters analysis shows that reinforcement quantity in the composite has the maximum ranking weightage (statistical influence 72.72%) followed by welding current (22.98%), other parameter effect is negligible. The 3D surface plot reveals that maximum hardness lies in the region obtained with the welding current of 210–220 A with 10– 12 wt.% SiC and above. From the confirmatory experiments for hardness, it is seen that the experimental and mathematical model results were found fairly with a close agreement. [ABSTRACT FROM AUTHOR]

This work emphasizes the optimization of preheating temperature of TiB2 reinforcement powder with LM4 composites, and statistical analysis for predicting hardness improvement during aging treatment using ANOVA, are illustrated in this article. A two-stage stir casting procedure was used to fabricate LM4 + TiB2 (1, 2 and 3 wt.%) composites. The impact of preheating TiB2 reinforcement powder at various temperatures such as 600, 500, 450, 350 and 250 °C, to attain uniform distribution of reinforcements in the matrix was studied. Optical microstructure analysis clearly shows that the optimum preheating temperature of TiB2 powder for effective preparation of composites is 350 °C for 30 min without agglomeration of reinforcement particles. After successful preparation of composites, the as-cast samples were subjected to single-stage and multistage solutionizing treatments and then artificially aged at 100 and 200 °C to obtain peak hardness. Micro Vickers Hardness test was done to calculate the hardness of both age hardened LM4 alloy and its composites and results were analyzed. An increase in wt.% of TiB2 (1–3%), the hardness of composites increased, and multistage solutionizing treatment followed by artificial aging at 100 °C was proven to achieve the highest peak hardness value for LM4 + 3 wt.% TiB2 composites. Compared to as-cast LM4 alloy, 80–150% increase in hardness was observed when aged at 100 °C and 65–120% increase in hardness was observed at 200 °C during SSHT and MSHT, respectively. ANOVA was performed with wt.%, solutionizing type, aging temperatures as factors, and peak hardness as the outcome. From the results, it can confirm that all three factors contributed effectively for achieving the peak hardness. R2 value validates that the factors account for 100% of the variance in the hardness results. [ABSTRACT FROM AUTHOR]

In this article, aspects related to A319 (AlSi5Cu3) and A356 (AlSi7Mg) alloy are covered owing to their prominent role in the automotive and aerospace industries. It is important to collect overall information related to these alloys and process them so that the material properties can be improved easily in the future by the addition of various trace metallic elements such as Mg, Sr, Sc, Cu, No, Ti, B, Mn, V, Zr and Ca. The addition of Mg (up to 0.45 wt.%) has been identified as the best way to improve tensile properties. It has also been identified that Sr addition modifies eutectic Si morphology and increases tensile properties. The presence of Cu causes the formation of Al2Cu which must be taken care of with proper treatments. Ni addition reduces the effect of Fe phases, and Sc addition improves the tensile properties. Various methods that can be used to produce the alloys mentioned above, related heat treatment processes, and parameters were briefly discussed. The influences of various reinforcements, modifiers, and grain refiners are presented. Solution heat treatment is implemented to dissolve intermetallic phases and the various parameters for aging treatment, cooling rate, and temperature to be used to improve the mechanical properties are also discussed. Among the various heat treatment processes, two-stage solutionizing treatment outperforms single and triple stage treatment processes in terms of improving the mechanical properties. [ABSTRACT FROM AUTHOR]

Steel is a versatile metal, got a wide range of applications in all the fields of engineering and technology. Generally, low carbon steels are tough and high alloy carbon steels are hard in nature. Certain applications demand both properties in the same steel. Carburization is one such technique that develops hard and wear resistant surfaces with a soft core. The objective of this work is to study the influence of post carburizing treatment (normalizing) on three grades of steels (EN 3, 20MnCr5, and EN 353). Post carburizing treatments are necessary to overcome the adverse effects of carburization alone. Here carburization was carried out in the propane atmosphere by heating the gas carburizing furnace to 930 °C for more than a day. Normalizing was carried out at 870 °C for 1 h and cooled in air. Tensile, hardness, Charpy impact tests along with SEM (scanning electron microscopy) and EDAX (energy dispersive X-ray analysis) were conducted to analyze the phase transformation, failure mode analysis in all the samples. Carburized steels displayed the formation of ferrite, pearlite, and sometimes bainite phases in the core and complete coarse pearlite in the case regions, whereas in the post carburized steels, increased amount of ferrite, fine pearlite, and bainite in the core and fine pearlite with traces of bainite in the case region was observed. Normalizing also refines the grain with increased UTS (ultimate tensile strength), hardness, and impact resistance. EN 353 showed higher UTS among the steels with 898 MPa after carburization and 1370 MPa after normalizing treatment. Maximum hardness of 48 HRC was observed in 20MnCr5 and toughness was superior in EN 3 with energy absorbed during test i.e., 8 and 12 J before and after normalizing treatment. Based on the fracture surface analysis, in EN 353 steel, a finer array of dimples with voids and elongated bigger clustered dimples containing ultrafine dimples array are observed in the core and case respectively during carburizing whereas, more density of river pattern and cleavage failure (brittle) are observed in the core and case respectively after post carburizing (normalizing) treatment. There is a reduction in the ductility of the steels after post carburizing treatment. It was observed that normalizing treatment produces superior mechanical properties in the carburized steels by grain refinement and strong microstructures like bainite. Normalizing as post carburizing treatment can be recommended for engineering applications where ductile core and hard surface are of great importance. [ABSTRACT FROM AUTHOR]

• Marine glass fiber reinforced composites are drilled. • The effects of seawater treatment on the increase in drill-induced delamination failure are investigated. • Different material thicknesses (6, 8, and 10 mm) and immersion times (20, 40, and 60 days) were examined. • The significance of spindle speed as an input deciding parameter is emphasized. • The increase in peel up delamination failure seen after 60 days of seawater immersion was 290.22, 305.86 and 250.81 %. • The increase in the push down delamination failure seen after 60 days of seawater immersion was 69.48, 76.38 and 64.28 % in 6, 8 and 10 mm composites. Composite materials, particularly glass fiber reinforced polymer (GFRP) composite, have established a strong presence in the marine industry. Its marine applications range from constructing massive naval vessels to constructing simple fishing boat hulls. Previous research has established that seawater aging has a detrimental effect on the physical and mechanical properties of GFRPs. Additionally, drilling composites are known to cause delamination damage, resulting in a high failure rate. Since composite components are assembled with fasteners, drilling operations are unavoidable. Thus, the current study examines the effect of seawater aging at a macroscopic level while considering the input parameters spindle speed and feed and material thickness and the response variables as peel-up and push-down delamination damages. The result indicated higher failure rates in the seawater-treated composites than in untreated composites. The maximum damages were seen in the 60 days of immersed composites, wherein the peel-up delamination damage increased by 290.22, 305.86, and 250.81 %, and the push-down delamination damage increased by 69.48, 76.38, 64.28 % in 6, 8 and 10 mm composites, respectively. The combinational effect of seawater degradation of GFRP composites and the damages caused by the cutting forces (function of speed and feed) attribute to the failure rate increase concerning the drilling-induced delamination damages in the composites. In addition to investigating the effect of seawater immersion on damages, the study also provides the regression analysis-based mathematical model having high goodness of fit and predicting capability to determine the damages for the given values of input variables. [ABSTRACT FROM AUTHOR]

Epoxy resins are prone to serious moisture absorption inspite of their inherent advantages, which can be mitigated by the incorporation of montmorillonite nanoclay that provide tortuous path to flow of moisture. Moisture absorption studies of epoxy clay nanocomposites is carried out, to analyse the effect of nanoclay content, immersion media and immersion temperature. Nanocomposites prepared in 0.5, 1 and 1.5 wt% using magnetic stirring and ultrasonication and neat epoxy specimen were immersed in distilled water and artificial seawater maintained at 28 and 38 °C till saturation. Fick's and Langmuir's models were applied to calculate the kinetic parameters from the water absorption graphs. Atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope with energy dispersive X-ray (SEM–EDX) characterizations were performed. Diffusivity is least for nanocomposite containing 0.5 wt% nanoclay at both temperatures in both medium. However, it is least when the medium is distilled water. As the temperature of immersion medium increases, the diffusivity also increases. Saturation moisture uptake increased with increase in nanoclay content, because of the residual hydrophilic nature of nanoclay. AFM and XRD analysis revealed better dispersion and exfoliated structure of nanoclay respectively at 0.5 wt% loading. FTIR spectroscopy was applied to identify the chemical bonds that helped in proposing the reaction mechanism of the nanocomposite synthesis. Spectra comparison of dry and wet specimens complimented the moisture absorption data by showing lower infrared transmittance in wet specimens. With Increase in nanoclay content, the transmittance decreased corresponding to increase in saturation moisture uptake for distilled water immersed specimens. SEM–EDX analysis distinguished between the cations entered from the artificial seawater and cations that were still present in the nanoclay. [ABSTRACT FROM AUTHOR]