Salt Spray Test on 3 year old Zinc Die Casting Chromed part per ASTM B 117-03

[jordigolo]

Hi all,

I've been testing some zinc die casting parts that were chrome plated 3 years ago.

Requirement is 240 hours as per ASTM B 117-03 and results are not good. Cr & Ni layer thickness have been found Ok.
If salt spray test is considered as an accelerated ageing process, is there any max delay for making these tests since coating is applied?

 

[Marc]

I would think it would in large part depend upon how the parts were packaged / preserved over the 3 years they were in stock. Salt spray testing is essentially a accelerated corrosion aging test.

 

[Umang Vidyarthi]

Hi all,

I've been testing some zinc die casting parts that were chrome plated 3 years ago.

Requirement is 240 hours as per ASTM B 117-03 and results are not good. Cr & Ni layer thickness have been found Ok.
If salt spray test is considered as an accelerated ageing process, is there any max delay for making these tests since coating is applied?

Marc has well advised you on your querry.

You have said that the dies were plated 3 yrs. ago. Now, were they in regular or intermittent use in this duration? If not, then how were they stored in the die room. These points are important, because normally the dies are exposed to normal weather conditions in the die room, barring exceptions.

If the dies were exposed to normal weather, then the ageing was 'on' in this duration, that is the reason why they have failed the 'salt spray test' of 240 hrs. It is apparent that plating of your dies was already deteriorated in those 3 yrs time. The 'salt spray test' has to commence before start of any ageing after the plating.

Umang