Galvanising bonds a layer of zinc to fabricated steel. It works two ways at once. There's a barrier (zinc covers the steel) and a sacrificial mechanism (when the coating is scratched, the surrounding zinc corrodes preferentially to the exposed steel). Two processes dominate: pre-galvanising (zinc applied to coil before forming, a thin coating around 20 microns) and hot-dip galvanising (whole fabricated assembly dipped in molten zinc, coating 60 to 100 microns).
Hot-dip is mandatory for outdoor structural metalwork meant to last decades. AS/NZS 4680 covers hot-dip galvanising specification in Australia. In coastal C5 corrosion-zone exposure, even hot-dip galvanising is typically followed up with a powder-coat top layer.
CAD60 model specifications default to galvanised steel. The title block can be set to record the corrosion category and finish.