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Go to Editorial ManagerThis study is focused on the assessment of the effects of Sulphur percentage in submerged arc welded API 5L X60 steel under conditions simulated to crude oil environments on its mechanical properties and microstructure. This involved immersing welded specimens in distilled water containing high (0.3250 ml/4L distilled water) and low (0.25 ml/4L distilled water) Sulphur concentrations for four weeks, while unimmersed samples were used as controls for comparison between the two groups of samples. The related experiments were tensile test, hardness measurements, SEM and EDS analyses and XRD analysis. The most mechanically degraded was the high- Sulphur group (H-group); yield strength of 441 MPa (17% loss) and ultimate tensile strength of 506 MPa (11% loss). For the low-sulfur group (L-group), reductions were more moderate: 467 MPa and 523 MPa, respectively. Weld metal (WM) and HAZ hardness values in the H-group were 203 HB and 208 HB, respectively, while those of the L-group were 208 HB and 214 HB. The H-group created a non-protective mixed layer of acicular iron oxides and iron sulfides (FeS) with respect to the microstructural aspects, whereas the L-group developed a thin protective film of iron oxide free from sulfides. Welding parameters were investigated for their effect on the corrosion rate and mechanical properties.
The aim of this work is to experimentally study the influence of fiber prestress and curing temperature on the tensile and flexural properties of carbon fiber-epoxy composite. Adaptive Neuro-Fuzzy Inference System model was used to predict the effect of fiber prestress and curing temperature on the tensile strength, tensile modulus, flexural strength and flexural modulus of carbon fiber-epoxy composite. It was found that, the best membership functions for predicting the tensile strength, tensile modulus and flexural modulus are Gaussian membership functions with 4 number of membership function, and for predicting the flexural strength are generalized bell membership functions with 4 number of membership functions. From the comparison between the experimental and predicted results of carbon fiber-epoxy composite properties, it is found that the prediction results of this model show a good agreement with experimental results.
The present work aims to build mathematical models based on experimental data to estimate the mechanical properties of submerged arc weldment. AISI 1020 low carbon steel plates 16mm thickness were welded according to orthogonal array in order to establish the relationship between input parameters (welding current, Arc voltage and welding speed) and output parameters (ultimate tensile stress, yield stress, impact energy and hardness) by submerged arc welding (SAW) process. The relationship between input and output parameters for the welding process are conducted using two suitable mathematical models the first one based on regression analysis, while the second one based on multi input single output ANFIS model for estimation of some mechanical properties of the welded plates. It was found that ANFIS results are closer to the experimental results than regression results. The optimal parameters (which give a maximum value of ultimate tensile strength (UTS), yield stress and impact energy; 446 MPa, 318 MPa and 213 J) are welding current is (380 Amp), Arc voltage is (25 V) and welding speed is (40 cm/min), while the maximum value of hardness number is (228 HV), when current welding is (380 Amp), Arc voltage is (25 V) and welding speed is (25 cm/min).
This work deals with the effect of using Recycled Concrete Aggregate (RCA) as a partial replacement of coarse aggregate in Self-Compacting Concrete (SCC), on the structural behavior (flexure and shear) of reinforced concrete one-way slabs. To the authors’ knowledge, this study is one of limited studies concerning the behavior of recycled aggregate concrete one-way slabs subjected to line loading with significant replacement of conventional aggregates by recycled concrete aggregate (up to 75 %). Three replacement ratios were considered: 25 %, 50 %, and 75 %. The mixes (with natural stone coarse aggregate, NCA) have an averaged compressive strength of ($F_{cu} = 42 \text{ MPa}$) at the age of 28 days with a tolerance of ($\pm 1.5 \text{ MPa}$). While, the mixes (with RCA) have an averaged compressive strength of ($38.5, 36.5, \text{ and } 34 \text{ MPa}$) for the three replacement ratios respectively, at the age of 28 days with a tolerance of ($\pm 2 \text{ MPa}$). All the slabs were cast with length of ($1600 \text{ mm}$), width of ($600 \text{ mm}$), while the thickness was variable. For this purpose, sixteen reinforced concrete one-way slabs were cast and divided into five groups (G1 to G5). Different parameters that affect the behavior of one-way slabs were studied and include type of failure, replacement ratios of NCA by RCA, amount of main reinforcement, thickness and locations of line loadings along the span. Hardened concrete specimens results show that the **compressive strength** $F_{cu}$, **tensile strength** $F_t$, **modulus of rupture** $F_r$, and **modulus of elasticity** $E$ were decreased as the RCA replacement increased. The experimental results of slabs show that the **ultimate capacity** of slabs decreased as the RCA replacement increased, the **deflection** and **strain** increase as the RCA replacement increases and the **crack width** increases as the RCA replacement increases. From the results of ultimate capacity, cracking load and moment, deflections, crack width and pattern and concrete surface strains, it can be concluded that the recycled concrete aggregate can be used as a partial replacement of natural coarse aggregate to produce self-compacting concrete mixes. Also, the behavior of one way slabs cast with SCC containing RCA is acceptable.
Friction stir processing is a new method of changing the properties of a metal through intense, localized plastic deformation ,this process mixes the material without changing the phase (by melting or otherwise) and creates a microstructure with fine, equiaxedgrains, It is used to improve the microstructural properties of metals. In this paper, the enhancement of mechanical propertiesof friction stir welding specimens at variable rotation speeds (1100, 1300 and 1500 rpm) with constant feed speed (60mm/min) for 6061-T6 aluminum alloy is studied by using the friction stir processing method at the same variable rotation speed and feed speed in order to transform a heterogeneous microstructure to a more homogeneous, refined microstructure. The best results of the welding line at the parameter 60 mm/min weld speed and 1300RPM rotation speed for the friction stir welding (FSW) and friction stir processing (FSP) where the efficiency reaches to 84.61% for FSW and 89.05% for FSP of the ultimate tensile strength of the parent metal.
The effect of thermal aging on the tensile properties of cast stainless steel during service in light water reactors has been evaluated and recorded by the Argonne National Laboratory. Tensile data for several experimental and commercial heats of cast stainless steel (CF-8M) are presented for predicting the change in tensile flow and yield stresses and engineering stress-strain curve as a function of time and temperature of service in the light water reactors using Neural Networks. Thermal aging increases the tensile strength of this type of steel. The result and correlation described by this work may be used for assessing thermal embitterment of cast stainless steel components.
This study is to investigate the effect of partially replacement of coarse aggregate by waste plastic and using the paper sludge as additive material at concrete, on the hardened concrete properties and its impact on structural behavior of the reinforced concrete members (slab, column, and beam). Plastics and paper are widely used in daily life in huge amounts. Both incineration and landfilling are options for disposing of plastic and paper waste, but either one could be harmful to the environment. Therefore, reducing waste or increasing its value can reduce pollution and reduce disposal costs. The variables of the experimental program include the ratio of waste plastic and paper sludge, the used ratios for plastic and paper were (5%, 10%, and 15%) by volume. Hardened concrete properties were investigated for concrete include: flexural strength, modulus of elasticity, and splitting tensile strength. For each structural reinforced member, the (Load – Deflection) curve has been extracted. The study shows that the plastic waste negatively affects most of concrete properties. The research indicates that using waste plastic in reinforced concrete members with percentage of (5% and 10%) by volume as a partially replacement of coarse aggregate giving acceptable results. However, when adding (5%) by mixture volume of waste paper in reinforced concrete members, the load-deflection behavior and ultimate load-bearing capacity have been improved. In general, using waste plastic and paper sludge in concrete mixtures lead to reduction in ultimate load ranging between (4.62%-10.82%) for slab under point load, (4.85-18.99%) slab under distributed load, (3.72%-12.21%) column, and (1.78%-7.16%) beam specimens respectively.
Co-Cr alloys are widely used in dental and medical equipment since the development of the first cast Co-Cr-Mo alloy. This is due to its high mechanical properties and high resistance to wear and corrosion. This research aims to study the effect of the fabrication method (Investment Casting and Selective Laser Melting SLM by 3D printing) and heat treatments on the mechanical and tribological properties of Co-Cr-Mo alloy. It was found that the Selective Laser Melting method in general increases the ultimate tensile strength, strain and hardness compared to the Investment Casting method. Also, solution treatment and aging reduce the strength and strain values of the SLM samples and have no obvious effect on the casting samples. The wear test shows that wear rate of casting samples is lower than that of SLM samples.
This article provides an overview of the studies that have been conducted on the characteristics of epoxy resins containing various types of silica nanoparticles and microparticles, as well as their performance in the industrial application of functionally graded materials (FGMs). Silica nanoparticles and microparticles are used to create epoxy resins in order to improve various properties, such as thermal stability, adhesiveness, electrical conductivity, strength, modulus, and toughness. This review examines the literature that has been published in the last decade, compares the results, focuses on the mechanical and thermal properties, and discusses the changes that have resulted in improvements in those properties. Previous experimental findings are presented and contrasted to demonstrate the extent to which silica filler content contributes to improving the properties of composite materials. The findings reveal that the characteristics of epoxy compounds can be improved by adding a particular amount of silica particles. There is a correlation between an increase in the silica amount and an increase in the Young modulus of epoxy compounds, this correlation becomes stronger as the silica amount increases. Additionally, the tensile strength of epoxy compounds increases to a certain limit as the amount of silica nanoparticles increases. In contrast, the hardness of the material increases as the silica amount increases. The density of the material also increases steadily as the silica amount in the material increases. According to thermal analysis results from calorimetric research on epoxy–silica systems, the glass transition temperature increases as the silica amount increases.