the specimens were immersed in 250 mL beaker contained 250 mL 1 M HCl with and without addition of different concentrations (50, 100, 200, 400 and 500 ppm by weight) of the tested inhibitors at 25 °C. After 24 h, the specimens were taken out, washed, dried, and weighed accurately. The corrosion rate (CR) and the inhibition efficiency (η %) were calculated using the following Eqs. (1) and (2):