Bluescope Steel Limited

Bryan Andrew Shedden

Qiyang Liu

Ross McDowall Smith

Wayne Andrew Renshaw

Joe Williams

Aaron Kiffer Neufeld

David James Nolan

Ross Mcdowall Smith

Red rust staining of Al/Zn coated steel strip in 'acid rain' or “polluted” environments can be minimised by forming the coating as an Al—Zn—Si—Mg alloy coating with an OT:SDAS ratio greater than a value of 0.5:1, where OT is the overlay thickness on a surface of the strip and SDAS is the measure of the secondary dendrite arm spacing for the Al-rich alpha phase dendrites in the coating. Red rust staining in “acid rain” or “polluted” environments and corrosion at cut edges in marine environments can be minimised in Al—Zn—Si—Mg alloy coatings on steel strip by selection of the composition (principally Mg and Si) and solidification control (principally by cooling rate) and forming MgSi phase particles of a particular morphology in interdendritic channels.

Corrosion protection with Al/Zn-based coatings

Red rust staining of Al/Zn coated steel strip in 'acid rain' or 'polluted' environments can be minimised by forming the coating as an Al&#x2014;Zn&#x2014;Si&#x2014;Mg alloy coating with an OT:SDAS ratio greater than a value of 0.5:1, where OT is the overlay thickness on a surface of the strip and SDAS is the measure of the secondary dendrite arm spacing for the Al-rich alpha phase dendrites in the coating. Red rust staining in &#x201c;acid rain&#x201d; or &#x201c;polluted&#x201d; environments and corrosion at cut edges in marine environments can be minimised in Al&#x2014;Zn&#x2014;Si&#x2014;Mg alloy coatings on steel strip by selection of the composition (principally Mg and Si) and solidification control (principally by cooling rate) and forming MgSi phase particles of a particular morphology in interdendritic channels.

A method of treating an Al/Zn-based alloy coated product that includes an Al/Zn-based alloy coating on a substrate is disclosed. The method includes the steps of rapid intense heating of the alloy coating for a very short duration, and rapid cooling of the alloy coating, and forming a modified crystalline microstructure of the alloy coating.

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Albion Park, Australia

Bryan Andrew Shedden