Letter 32093

Passivation of 15-5 PH and 17-4 PH steel  

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We are trying to do passivation of 15-5 PH steel & 17-4 PH steel with HNO3 + HF [3:1]solutions. The results are not so encouraging since overetching of surface is taking place.

Request to suggest most suitable process for passivation of these steels. Can Phosphoric acid + Chromic acid or Nitric acid + Sodium Dichromate process be used for these steel? Which is most suitable?

Biren Desai
Godrej & Boyce Mfg. Co. Ltd. - Mumbai, Maharashtra, India

Biren,

Take a look at QQ-P-35 [link is to spec at TechStreet] for the proper method to passivate 17-4PH and 15-5PH Stainless Steel.

Tim Hamlett
Techno Coatings, Inc. - Miami, Florida

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