Conventional quenching versus ZnO-NP emulsion and heat treatments for medium carbon steel (CK45) has been carried out in laboratory environment condition. For comparison, the mechanical properties of CK45 and microstructure were examined. The main parameter focused in this work was the concentration of ZnO-NP in deionized water. Thus, emulsion represents a quenching medium for CK45 specimens. Optical microscope analysis for CK45 microstructure, hardness and tensile test for all specimens were done to evaluate the role of nano ZnO additives as quenching media at different concentration. Experimental results reveal that the addition of nanoparticles to the base fluid (water) astonishingly enhanced some mechanical properties as tensile strength and yield stress. 2wt.% of ZnO-NP raised the yield 14.8% and the UTS by 16.9%.
The stir casting process used to manufacture the AL/Al2O3. AA2024 with matrix material alumina Al2O3 at different weight percentage ratio 0.3, 0.5, 0.7 and 0.9%. Were fabricated by using cryogenic temperature (CT). It was observed that the maximum enhancement is occurred at nanocomposite containing 0.9% Al2O3 which shows improvement percentage of 9.9%, 14.63% and 14.28% for ultimate strength, yield stress and Brinell hardness respectively and the ductility is reduced by 34.57% compared to 0% by weight AA2024. It clearly shows that all the mechanical properties are improved by increasing weight percentage of Al2O3 but the best properties are obtained at 0.9% Al2O3 nanocomposite. The fatigue S-N curve tests were done for all the specimens having average of roughness between 0.2 to 0.5Mm.The fatigue endurance limit of the 0.9% wt. Al2O3 composite into two cases without (CT) and with (CT) is taken at 107 cycles. The fatigue limit at 107 cycles increases from 83 MPa for without (CT) to 89.6 MPa with (CT) resulted in 7.95% fatigue limit improvement.
A study of new Track of Fatigue crack growth in aluminum alloy (2219) under cyclic stresses has been made. It was found out that this crack grow and propagate in three phases, the first phase though the grain size (micro-structure short cracks(MSC)), second phase cross the boundary of the grain size to about 1mm in length (physically short cracks (PSC)) and the third phase up to the final fracture (Length cracks(LC)). In addition, two programs were designed on MATLAB to perform the compute calculations to collect the results. The first program to calculate the practical constants and the second to make the calculations required to complete the work schedules. The stress and the parameters effecting the growth of these cracks in each phase were studied. A model consisting of three formulas was established from the experimental results. Each formula describes the behavior of the cracks in the particular phase. The comparison showed that the proposed model is safer than the experimental results for the designed parts of aircraft.
The steel infrastructure is continuously under corrosive attack in most environmental and industrial conditions. There is an ongoing search for environmentally friendly, highly effective inhibitor compounds that can provide a protective action in situations ranging from the marine environment to oil and gas pipelines. The corrosion inhibition of transmission steel in 1M HCl cell in the presence of succinic acid at temperatures (20,30,40,50 and 60) °C at concentrations within the range (10−6- 10−4) M for two hours using the weight loss method (WLM). The results showed that the inhibition efficiency increases with increasing inhibitor concentration and increases with temperature up to 60°C. The activation significance of the corrosion rates was calculated as the activation energy Ea, the change of the activation entropy ΔH, and the change in the activation entropy ΔS. Also, results show that the inhibition efficiency was increased with the increase of inhibitor concentration and increased with the increase of temperature up to 60°C. Activation parameters of the corrosion process include activation energies (Ea), activation enthalpies (ΔH), and activation entropies (ΔS). The results also showed that the adsorption of the inhibitor is subjected to the Langmuir law, and the maximum efficiency reached approximately 97% at 60°C in the 10−4M inhibitor concentration.
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