ASTM B Type II and III zinc chromate plating Q&A’s. greater corrosion resistance is required, e.g., for SC3 & SC4 (13 & 25 microns zinc, respectively). Blue/Zinc. Blue/Zinc. Yellow/Zinc. Yellow/Zinc. ASTM B Type II SC 3 (FE/ZN 13). Type II SC 2 (FE/ZN 8). Type II SC 1 (FE/ZN 5). Type III SC 3(FE/ZN 13). ASTM A/AM Low and Intermediate Tensile Strength Carbon Steel Plates .. ASTM B Electrodeposited Coatings of Zinc on Iron and Steel.
This is not considered a decorative finish and will not generate matching parts. I need to specify platings that do not contain Hexavalent Chromium for parts that will be used in the automotive industry. Our plater would like to go to asm 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.
Decorative charastreistics The exterior visual determined according to last layer. Go to main content.
Thank you for your hard work which the finishing world continues to benefit from. 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. The problem may not be with the chromate at all.
The Zinc coating on the steel does not last shiny for long, and so a further thick layer coating is added, called passivation. Answer is based upon pre versions of B, Hi, I recently received 2 batches of parts from two separate platers using this specification. The exterior visual determined according to last layer.
Our Zinc coating is carried out according to: There are different passivation colors: The coating is made according to demand, where the distribution is as follows: Yellow chromate should get 96 hrs to failure.
Sorry, but if you need one particular look, you must go through the ugly process of maintaining sample boards with acceptable vs. A Blue with pale yellow is the best replacement for yellow as of now.
ASTM B – Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel
I’m not a zinc plater, but ‘Type 31 Clear’ seems self-contradictory. Does anybody know this info? But if you are looking for something indisputably blue, as opposed to clear with a possible slightly bluish cast, this probably requires dye.
Surfaces to be painted should be ONLY lightly chromated. To minimize your searching efforts and to offer multiple viewpoints, we’ve combined some threads into the dialog you’re viewing.
As the USA moved toward metric fasteners, for a while there was a move to dye them blue. Our plater said that he would be willing to go thicker on the clear. Trivalent chromates give paler and lighter finishes; some use metals, some use permanganates, some use dyes, in order to replicate the Hex finish.
Perhaps some confusion with Service Condition SC 2 moderatewhich indicates a minimum zinc thickness of 8 microns and is commonly clear chromated Type III. Surfaces left-bare should be heavily chromated. How do you know if it is supposed to be Zinc Yellow or Zinc Clear?
ASTM B-633 Type II vs. III zinc plating
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.
I’ve seen this done less commonly on chromated zinc plating than on chromated aluminum.
Zinc coating with colorful RoHS compliance passivation. Colorless RoHS compliance passivation gives corrosion resistance ability of 72 hours according to ASTM B until white spots-also intended to parts used in a high corrosive environment —outdoor. 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.
It definitely implies Hex G633.
Is this process done in the United States, and if so by whom? As much as the last layer of the passivation is thin the electrical resistivity is low. All I need to know is what color the types are. No it does not imply that. The satm resistance of this green layer passivation is very high because it is thick in relative to other passivations. Is there any colour difference OR is there any Salt spray aztm From beautiful Pine Beach New Jersey: Put the chromate on light.
Zinc plating is usually considered a functional coating, not a decorative one. Iron metals rust relative quickly, even in a non-corrosive environment. Regarding the question asked in letter ; Type II zinc plating vs. Colorful chromate passivation gives corrosion resistance ability of 96 hours according to ASTM B until white spots-intended to parts used in a high corrosive environment —outdoor.
Try using an acid zinc chloride bath and see if the casting covers.