High strength steels tensile strength greater than M.
#ASTM B633 STANDARD PDF PROFESSIONAL#
Type III With supplementary colorless chromate treatment.īarrel Zinc – Finishes – Professional Plating Inc. Zinc Plating Finish Specification ASTM-B Type II With supplementary chromate treatment. Type II, Zinc coating with colorful chromate passivation, 96 hours 48 hours. ASTM B ELECTRODEPOSITED COATINGS OF ZINC ON IRON AND STEEL.
Corrosion Resistance-Zinc coatings with Types II, III. chaser shall state ASTM B, the date of issue, service. The 2007 revision addresses RoHS concerns and specifically allows non-hexavalent chromate treatments.Designation: B − Standard. opacity, although this is not platers' usage. Also, some yellow chromates are clear w.r.t. Obviously, this must be clarified by the customer. Type II chromates are more commonly used where greater corrosion resistance is required, e.g., for SC3 & SC4 (13 & 25 microns zinc, respectively). In this case, the designation would be Fe/Zn 8 Type III. Perhaps some confusion with Service Condition (SC) 2 (moderate), which indicates a minimum zinc thickness of 8 microns and is commonly clear chromated (Type III). See ASTM B633 -07, 'Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel.'įe/Zn Type II indicates an iron or steel substrate, electroplated with zinc, followed by a Type II treatment (colored chromating).* Two problems with the given print specification:Ģ) 'Clear' isn't defined in B633 but ASTM B201-80 mentions 'colorless (clear bright).' Colorless chromate is Type III per B633. I'm not a zinc plater, but 'Type II Clear' seems self-contradictory. No, other colors may not be available if my presumption is right.Ī. Do they use Hex or Trivalent chromium, are they available in colours, and do they protect as well as the type II or III finishes?Īns: 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. It still will have Hex Chrome.Ĥ I have not heard much about the Type IV finishes. Type III (colorless) generally refers to Hex Chrome that has been bleached off to give a clear look. A Blue with pale yellow is the best replacement for yellow as of now.ģ Do all ASTM B633 Type III platings NOT use Hexavalent Chromium?Īns: No it does not imply that. 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. It definitely implies Hex Chrome.Ģ Can you get a type II finish that uses Trivalent?Īns: Trivalent chromates give paler and lighter finishes some use metals, some use permanganates, some use dyes, in order to replicate the Hex finish. ASTM B 633 and all other worldwide standards were written around the time when no one spoke about trivalent. In response to your questions re ASTM B 633 I have an old version of the spec so my opinions are based upon the one I have.ġ Do all ASTM B633 Type II platings use Hexavalent Chromium?Īns: The answer is Yes. My compliments for an excellent round of questions!
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