الفهرس 
INTRODCUTIONOnly 14 pages are availabe for public view
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Abstract
Corrosion has been defined as an irreversible interfacial reaction by chemical or electrochemical processes of a material with its environment destroying valuable properties of the material. The chemical analysis of tested steel alloys (steel alloy 4130, high strength alloy and mild steel alloy) and their mechanical properties are measured. The tensile strength, hardness, percentage elongation and yield strength for the steel alloy specimens were obtained at room temperature. Hardness testing and tensile strength were carried out for steel alloy 4130 after immersion in NaCl 3.5 wt.% for 10 days at 50 oC. Density functional theory (DFT) calculations were used for better understanding of the structure of the inhibitor (aqueous Lawsonia Inermis extract). Electrochemical techniques such as; open circuit potential (OCP), potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) are used to observe the action of corrosion in 3.5 wt.% NaCl solution. Inhibitor has acted as a corrosion inhibitor by producing a thin protective layer on the metal surface. The scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analysis were applied as a complementary tool for surface characterization. In addition, Box-Behnken method was used to investigate the effect of key parameters (i.e. concentration of inhibitors, temperature, and speed of rotation) on the efficiency of inhibition and corrosion rate of steel alloys in 3.5 wt.% NaCl solutions. from electrochemical measurements and statistical analysis, it was found that the efficiency of inhibition improved with higher inhibitor concentration, low rotation speed and low temperature.