Corrosion

Corrosion Resistance

light

moderate

severe

very severe

	Corrosion Conditions	Galvanic Corrosion	Hexavalent Chromium	Electrical Conductivity	Temperature Resistance	Appearance	Availability	Cost
Zinc plate + yellow passivation		Refer to Chart	Yes	Conductive	Moderate/ Low	Iridescent Yellow	Moderate/ Good	Low
Zinc/nickel plate + yellow passivation		Refer to Chart	Yes	Conductive	Good	Iridescent Yellow	Moderate/ Good	High
Zinc plate + clear passivation		Refer to Chart	No	Conductive	Moderate	Clear/ Metallic Blue Tinge	Good	Low
Zinc plate + clear passivation + sealer		Refer to Chart	No	Conductive	Moderate	Clear/ Metallic Blue Tinge	Good	Moderate
Zinc/nickel plate + clear passivation		Refer to Chart	No	Conductive	Good	Clear/ Metallic Blue Tinge	Good	High
Zinc/nickel plate + black passivation		Refer to Chart	No	Conductive	Good	Black	Good	High
Zinc plate + Deltaseal		None	No	Non Conductive	Moderate	Black Silver	Good	Moderate
Zinc/nickel plate + Deltaseal		None	No	Non Conductive	Good	Black Silver	Good	High
Phosphate and Deltaseal		None	No	Non Conductive	Moderate	Black Silver	Good	Moderate
Zinc/nickel plate + KTL		None	No	Non Conductive	Good	Black	Moderate	High

	Typically indoors and warm dry atmospheres.
	Typically indoors where moisture can occur. Outdoors in mild corrosive conditions.
	Typically outdoors in moderate corrosion conditions for example light industrial and possibly external vehicle applications.
	Typically outdoors in severe corrosive conditions for example marine, industrial or vehicle engine compartment or under body.

Galvanic Corrosion

• Select metals which are as close together in the chart as possible.
• Provide a barrier between the metals, such as paint, non-metallic washer, gaskets or jointing compound.
• Design the fastener as the cathode so that the cathodic area is as small as possible to the anode area.
• Use a metallic finish on the fastener that is close on the chart to the mating metal.
• Use a non-conductive and inert finish on the fastener.