Mechanical properties of zinc-aluminum film on steel cable substrate in corrosion environment

Abstract

This paper presents an experimental program aimed at finding out the effect of salt spray corrosion on the mechanical properties of the film in the zinc-aluminum film/304 stainless steel substrate system. At first, the salt spray tests were carried out on the film/substrate specimens to observe the corrosion phenomenon and obtain the porosity of the zinc-aluminum film. Then, the three-point bending tests were carried out on the specimens with different film thicknesses and different corrosion time by a universal testing device equipped with an acoustic emission system (AE) to obtain the effective elastic modulus of the corroded film. After that, the crack-initiation threshold of the film was accurately detected to further obtain the fracture toughness of the corroded film by AE system. Also, tensile tests were used to obtain the critical film thicknesses and the relationship between crack spacing and the film thickness of the corroded film under different strains. The test results illustrated that the effective elastic modulus and fracture toughness of zinc-aluminum film decrease with the increase of corrosion time; the porosity of the film decreases with the increase of the film thickness; the decline rate of the effective elastic modulus and fracture toughness of the corroded film can be decreased by slightly increasing the film thickness; the critical thickness of the film decreases with the increase of tensile strain and the corroded film is easier to crack than the non-corroded film due to the decrease of critical cracking strain.