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Chromating of zinc phosphate coated part
[an error occurred while processing this directive]1) Is it possible to carry out trivalent chromating treatment over zinc phosphated surface (spring steel)? If so, what would be the corrosion protection?
2) Is it mandatory if a spring steel subjected to zinc phosphating treatment?
PROCESS DESIGNER - CHENNAI, TAMILNADU, INDIA
January 27, 2010
1. Whether hydrogen de-embrittlement is required for a zinc phosphated spring steel component?
2. Is it possible to do chromate conversion coating directly on degreased, de-rusted steel part?
- CHENNAI, TAMILNADU, INDIA
January 28, 2010
February 2, 2010
I don't know of a trivalent seal for zinc phosphate, I've only ever used a hexavalent version. You may want to ask your chemical suppliers about whether there is a trivalent option.
Spring steel will almost certainly need de-embrittlement. Steels greater that about 1100MPa are regarded as high strength steels and will require de-embrittlement as soon after treatment is completed as possible, preferably within 1 hour. Standard de-embrittlement would be at 195C (approx. 375 °F), the time would vary, dependent on the steel strength.
If you search the letters on this site you will find numerous threads relating to de-embrittlement of high strength steels.
Aerospace - Yeovil, Somerset, UK
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