It is known that heat treatment (HT) highly affects the properties of base metal (BM) and fusion zones (FZ) of duplex stainless steel (DSS). In fact, it may give unwanted structure changes. Duplex stainless steels SAF 2205 welded joint was subjected to thermal cycle at temperature of 850◦C at holding times 1, 3, 5 and 7 hours. The influence of heating cycles and concentration of corrosive medium on the corrosion properties and microstructure of 2205 alloy was the objective of this work. It was found that process led to noticeable decrease in the corrosion resistance of BM and FZ specimens; moreover the decrease was large in BM than FZ. It was also found that sigma phase (σ) precipitated in the different zones of the structure. σ phase volume fraction was found to increase with increasing the holding time of HT, and its increase is larger in BM. Corrosion resistance was found to be oppositely related to σ phase formation. Secondary austenite phase (γ2) was also precipitated and its volume fraction in FZ was found to increase with increasing the holding time of HT and decreased in BM.
Eutectic Al-13 wt. % Si and hypereutectic Al-16 wt. % Si were prepared by using permanent mould casting technique. Effect of the cooling technique on the cast microstructure, mechanical properties, and electrical conductivity of Al-Si alloys was investigated by using the conventional water-cooled and air-cooled methods. The mechanical properties such as the yield stress, tensile strength, hardness, and impact energy were measured at various cooling methods. Microstructure with scanning electron microscope (SEM) and Energy dispersive spectrometer (EDS) analysis of Al-Si alloys have been studied. In addition, the hardness after solution treatment at 529 °C for 2 h and artificial ageing at various temperatures 180 °C and 210° C for aging time 2-10 h was measured. The results show enhancement in the mechanical and electrical properties for the eutectic Al-13 wt. % Si and hypereutectic Al-16 wt. % Si alloys for the water-cooled over the air-cooled technique. In addition, the largest value of the impact energy (4.91 J) was obtained for the eutectic Al-13 wt. % Si alloys compared to the hypereutectic Al-16 wt. % Si alloys at 3.09 J for watercooled-medium. The total solidification time (TST) of Al 13% wt. Si was longer than that time for the hypereutectic Al 16% wt. Si at various cooling mediums. Aging studies of Al-Si alloys with aging temperatures 180 ºC and 210 ºC show that the hardness values increased as the silicon content increases. For hypereutectic Al-16 wt. % Si at aging temperature 180 ºC and aging time 4 h by using water-cooled technique, it was observed that the maximum hardness value reached to 100 HRD compared that value was 87 HRD for the eutectic Al-13 wt. % Si alloy.
The relation between iron/copper bimetallic composites has many challenges; one of the most important characteristics is their diffusion and its effect on the properties of the interface region. This paper studies the influence of casting parameters on the interface region of these bimetallic composites and compares it to observations on those of the Quranic metal matrix composites based on the Dhul-Qarnayn dam (Gog and Magog Wall). A different number of steel rods (one, two, and three) were placed in an alloy steel mold, then heated at different temperatures of 350, 450, 550, and 650 °C. After that, molten copper was poured over them into the mold, followed by different cooling rates (fast, medium, and slow). The properties of the interface region (microstructure, microhardness, and bonding strength) were investigated. The finite element model was carried out to obtain the temperature distribution through the specimen. The microhardness test results revealed that the high preheating temperature and high cooling rate give a high interface microhardness due to the formation of iron oxides and fine grains. The present experimental results show the highest bond strength between steel and copper, which was achieved when the temperature of the interface region reached the austenitic phase (γ-phase) and held it sufficiently to reach a successful substitutional diffusion mechanism. The bond strength between copper and steel in each casting parameter obtained experimentally was used to predict the tensile strength of the obtained bimetal composites numerically.
This study was carried out to examine the mechanical properties of hypereutectic Al-16% Si alloy with the introduction of zinc oxide (ZnO) nanoparticles (NPs) synthesized by simple sol-gel method. The microstructure of the synthesized ZnO NPs was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructure of the synthesized ZnO NPs reflects the formation of the wurtzite-type ZnO and the average crystallite sizes around 35 nm. Hypereutectic Al-16% Si with varies concentration of ZnO NPs (0.5, 1, 1.5 and 3%) was synthesized utilizing permanent mold casting technique. Energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM) of hypereutectic Al-16 wt% Si alloys after the dispersion of these nanoparticles were analyzed. The results revealed that an addition of ZnO nanoparticle to hypereutectic Al-16wt % Si alloy enhanced the tensile strength, impact energy and the hardness. The maximum tensile strength, impact energy and hardness of this alloy was 200 MPa, 5.38 J, 60 BHN, respectively, which occurred at 3 wt% of ZnO NPs. This enhancement in mechanical properties can attributed to the decomposition and dissolution of the nano-oxide particles in aluminum alloy melt and grain growth restriction.
Electrical wires with melted ends showing beaded, drop-shaped, and pointed shapes are frequently encountered after fires that may provide useful information on the cause and development of the fire.Various methods have been studied for differentiating between primary arcing beads, (indicating arcing as the fire cause) and secondary arcing beads (indicating arcing as a result of the fire). There are few studies carried out on the melting globules produced due to fire heat. Also, in some major cases, primary arcing beads and secondary arcing beads are difficult to be identified by using one method. In this study, a full scheme of differentiating methods between simulated samples of melting globules, primary arcing beads and secondary arcing beads are processed with macroscopic investigation. The in-depth composition of carbon quantitative analysis and metallurgical analysis of these samples have been studied. The results of this study has proved that the real cases are compatible with simulated ones.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.