ASTM B Type II and III zinc chromate plating Q&A’s. *Note: Answer is based upon pre versions of B (, , ). The revision. Hi, can anyone advise if the ASTM std ASTM B [link by ed. to spec at TechStreet] std specification for Electroplated coatings on Iron and steel, the . ASTM Be1 Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel Scope This specification covers requirements .
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Numeral indicates thickness in micrometers. Going with clear will make it difficult to tell what is clear chromated zinc vs. To me “bright blue” does not usually literally mean “bright blue” like the sky or a robin’s egg. August 31, A. III is colorless and not expected to hold up as long as the colored II. He passed away May 14, This is not considered a decorative finish and will not generate matching parts. According atsm RoHS the homogeneous and non-homogeneous are defined in such manner that every one may understand that the layer is removable b633-89 see how.
The part is currently being produced in China and my local platers are suggesting a dye to get a blue color.
What process variation would produce these different results? From beautiful Pine Beach New Jersey: Zinc plating is usually considered a functional coating, not a decorative one.
The problem may not be with the chromate at all. How do you know if it is supposed to be Zinc Yellow or Zinc Clear? Any information would be well received. It does not cover zinc-coated wire or sheets.
We are getting poor coverage on the as-cast surface of some steel castings using a yellow Zinc chromate. III zinc plating A discussion started in but continuing through Q.
It definitely satm Hex Chrome. The answer is Yes. All information presented is for general reference and does not represent a professional opinion nor the policy of an author’s employer. It’s not possible to diagnose a finishing problem or the hazards of an operation via these pages.
Zinc Plating: ASTM B Type II vs. III
Obviously, this must be clarified by the customer. II says “colored chromate coatings” meeting 96 hours of salt spray, and III says “colorless chromate conversion coatings” meeting 12 hours of salt spray. Regards, Ted Mooney, P. Does plating make that big a difference knowing that it’s going to be painted also?
The revision addresses RoHS concerns and specifically allows non-hexavalent chromate treatments. Can anyone give me some direction on how to get the customer to accept going to clear. The end user must decide when a part fails, at “white rust” corrosion the chromate has failed or red rust both the chromate and the zinc are gone exposing the base metal. I will be attending the ASTM B8 committee meetings in Philly later this week and will mention this letter to the sub-committee chair responsible for the B spec.
Also, I found out that the casting is painted after plating. Not the least of which is the environmental regulations impact on the future of the selected finish. Supplementary treatments shall be in accordance with Recommended Practice B Did you ever get the answers you were looking for?
In 24 years I have only been asked this question once before and I presume it involves phosphating over zinc plating for those heavy phosphating grammage applications, where normal phosphating will not provide enough zinc phosphate that is required in the deposit.
Adtm if you need to color match, you need to do it with a requirement for compliance with sample parts — not a verbal description.
ASTM B633-98 std: Electrodeposited coating of Zinc
Until a very few years ago chromate conversion coatings were based on hexavalent chromium, and deposited a thick film that was relatively easy to dye.
As the USA moved toward metric fasteners, for a while there was a move to dye them blue. Corrosion Resistance Requirements Types.