STUDY OF MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF PURE ZN AFTER HIGH PRESSURE TORSION

Abstract

A study of the effect of high pressure torsion (HPT) on the structure, mechanical properties and corrosion resistance of pure Zn was conducted in this work. The studies have shown that HPT leads to a significant refinement of the microstructure of pure Zn: from 100–150 µm in the as-cast state to 700–800 nm after deformation. This grain refinement leads to an increase in the ultimate tensile strength of pure Zn from 89 ± 6 MPa to 260 ± 21 MPa. In addition to an increase in strength, the growth in ductility is observed (the elongation increased from 5.0 ± 1.0% in the as-cast state to 58.1 ± 21.1% after HPT). It should also be noted that the increase in mechanical characteristics is not accompanied by a deterioration in the corrosion resistance of pure Zn. Thus, the corrosion potential is –1005 ± 14 and –1016 ± 30 mV, the current density is 14.26 ± 4.77 and 8.37 ± 5.32 μA/cm2, and the degradation rate is 0.27 ± 0.09 and 0.16 ± 0.10 mm/y for as-cast and HPT-treated Zn, respectively. The data obtained allow us to conclude that HPT is promising for improving the strength characteristics of pure Zn without losing its corrosion resistance.