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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The part is currently being produced in China and my local platers are suggesting a dye to get a blue color. The designer and engineer must take into account several considerations to stay at the forefront of the finish potential.
Olive Drab chromate is hrs.
It does not cover zinc-coated wire or sheets. Surfaces left-bare should be heavily chromated. 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.
ASTM B-633 Type II vs. III zinc plating
I’ve seen this done less commonly on chromated zinc plating than on chromated aluminum. Thank asstm for your hard work which the finishing world continues to benefit from. Trivalent chromates give paler and lighter finishes; some use metals, some use permanganates, some use dyes, in order to replicate the Hex finish.
A Blue with pale yellow is the best replacement for yellow as of now. To me “bright blue” does not usually literally mean “bright blue” like the sky or a robin’s egg. The Standard default is gold for type II coatings unless otherwise specified. It still will have Hex Chrome. Is there any aetm difference OR is there any Salt asttm difference? B Where service conditions are valid only for coatings with chromate conversion coating.
Type II chromates are more commonly used where greater corrosion resistance is required, e. Put the chromate on light. So if you need to color match, you need to do it with a requirement for compliance with sample parts — not a verbal description. All I need to know is what color the types are. They share, however, the most basic of metal finishing requirements: But if you are looking for something indisputably blue, as opposed to clear with a possible slightly bluish cast, this probably requires dye.
Perhaps some confusion with Service Condition SC 2 moderatewhich indicates a minimum zinc thickness of 8 microns and is commonly clear chromated Type III. The revision addresses RoHS concerns and specifically allows non-hexavalent chromate treatments. I need to specify platings that do not contain Hexavalent Chromium for parts that will be used in the automotive industry. Did you ever get the answers you were looking for?
Could you explain this?
Until a very few b33-98 ago chromate conversion coatings were based on hexavalent chromium, and deposited a thick film that was relatively easy to dye. High strength steels tensile strength greater than MPa shall not be electroplated. How do you know if it is supposed to be Zinc Yellow or Zinc Clear? Hello Claudio and Doug, My compliments for an excellent round of questions!
Numeral indicates thickness in micrometers. I’m not a zinc plater, but ‘Type II Clear’ seems self-contradictory.
Zinc Plating: ASTM B Type II vs. III
III is colorless and not expected to hold up as long as the colored II. That seems a bit discretional to me. Our plater would like to go to a clear zinc, but our customer is under the assumption that the clear will not do as good a job with corrosion resistance and salt spray life. I have the exact same questions. He passed away May 14, It would be “bright, blue” — that is, shiny and metallic but with a bluish rather than a yellowish cast.
ASTM B633-98 std: Electrodeposited coating of Zinc
You can get the same finish only for blue and black hex chrome with tri substitutes, but not for yellow or olive as of yet. Our plater said that he would be willing to go thicker on the clear.
B6333-98, The “Types” define supplementary finishes to be done after the plating.