Coil-coated Zn-Mg and Zn-Al-Mg : Effect of climatic parameters on the corrosion at cut edges

• We studied the effect of temperature, wet/dry cycling, pH, and the type and concentration of the corrosion activator on cut edge corrosion of painted Zn-15Mg and Zn-1.5Al-1.5Mg coated steel. In most accelerated tests, paint delamination and red rust formation were reduced compared to hot dip galvanised steel (HDG), and Zn-15Mg outperformed Zn-1.5Al-1.5Mg; however, Zn-1.5Al-1.5Mg showed better results when exposed outdoors. The alloyed materials were particularly resistant when HDG was prone to elevated corrosion, i.e. under permanent wetness, at higher temperatures, with high chloride loadings and in the presence of sulphate. Oxygen reduction on steel cut edges was inhibited by the alloying elements.

Nyckelord

Alloy

Atmospheric corrosion

Metal coatings

Organic coatings

Zinc

Alloying

Alloying elements

Aluminum

Aluminum coatings

Chlorine compounds

Corrosion

Electrolytic reduction

Galvanizing

Zinc alloys

Zinc coatings

Accelerated tests

Climatic parameters

Cut edge corrosion

Effect of temperature

Galvanised steel

Oxygen Reduction

Rust formation

Wet/dry cycling

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