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Standards for Hydrogen Embrittlement Relief after Zinc Plating

Q. Does ASTM A572 Grade 50 material need to be baked after Acid Zinc/Nickel electroplating. If it does, at what temperature and for how long?

Richard Comp
- Greensboro North Carolina
September 1, 2021

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Q. I am a small metal stamping job shop. We sent some steel parts (SAE1050) to our heat treater and plater (zinc & bake). The parts failed in service. Our customer is claiming our plater didn't bake them right. The plater has told me what he did, but I have no idea how to evaluate if it's right or within any applicable standards or rules of thumb.

Is there a standard for how long and at what temperature parts should be "baked" after zinc plating?

Is there such a thing as "standard commercial zinc & bake"?

Thanks in advance.

Michael Wagner
- Toronto, Ontario, Canada
2002

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A. What did your PO state in the ordering documents? Did you indicate that the parts require baking? Different specs require different bake cycles and more importantly different delays following baking to the start of baking. The more critical the application and the more prone the parts are to embrittlement, the shorter this delay becomes. For many aerospace applications on hardened steels, above Rockwell C 36 hardness, this delay becomes 30 minutes. For most applications, commercial for instance, this becomes 4 hours. A conventional callout for baking parts following plating is: 375± 25 degrees F for 3 hours minimum within 4 hours of plating. For springs and parts that are subject to flexure or extreme loading, often this bake is extended to 8 hours or up to 24 hours in some cases. Most platers have baking charts and baking records that can be produced as objective evidence of baking the job. Check closely when the parts came out of plating and when they were at temperature ( should be less than 4 hours ). Failures of platers to bake parts properly or at all usually stems from lacking of citing a proper specification in the ordering document or not giving the plater enough information to indicate that the parts require baking. As Chairman of ASTM B8's subcommittee on coating pre- & post-treatment, I have seen and heard of many such problems. Operating a specification plating shop myself and having worked in the industry for thirty years, I've seen it all. Communications is key! Milt Stevenson, Jr. Syracuse, New York 2002 A. How do you know that it was an aspect of the plating that caused the service failures? Consider the possibility that there was a design deficiency, or that your client specified an inappropriate material, and hence the parts might have failed even if they had never been plated. Bill Reynolds [deceased] consultant metallurgist - Ballarat, Victoria, Australia We sadly relate the news that Bill passed away on Jan. 29, 2010. 2002

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2002

Q. "What did your PO state in the ordering documents? Did you indicate that the parts require baking?" It said zinc and bake.

"For many aerospace applications on hardened steels, above Rockwell C 36 hardness, this delay becomes 30 minutes. For most applications, commercial for instance, this becomes 4 hours." It's not an aerospace application, but it was 1050 heat treated to midrange for 1050 (Rc 39-43)

"A conventional callout for baking parts following plating is: 375± 25 °F for 3 hours minimum within 4 hours of plating." We are subcontract manufacturers. We stamp the parts according to the designers specs and handle post-processing according to the designers specs. In this case, the spec was "zinc & bake". Is there a "standard" interpretation for such a specification? Can the question "did our plater act within that spec" be answered meaningfully?

"Most platers have baking charts and baking records that can be produced as objective evidence of baking the job." Thanks. I'll follow up on that.

"How do you know that it was an aspect of the plating that caused the service failures?" Two independent labs analyzed a few failed parts. One said the parts were clearly underbaked for this application. The other said either they were underbaked or overbaked. Neither really addresses whether what was done to the parts falls within industry standard practice for a simple "zinc & bake" specification.

"Consider the possibility that there was a design deficiency, or that your client specified an inappropriate material, and hence the parts might have failed even if they had never been plated." I have tried to explain to our client that this was his responsibility to specify tighter if the parts were sensitive to this processing, but it's been tough sledding.

Thanks for your feedback, and I await more information.

Michael Wagner
- Toronto, Ontario, Canada

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Q. What time and temperature for hydrogen embrittlement process on zinc plated spring steel component ?
Thank You
With Regards

Sanjay Jain
plating and paintshop - India
February 17, 2009

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Q. The ASTM B633 makes reference to parts having an MPa 1200 is there a standard for zinc plating on C1022 carbon steel that has lower MPa

Douglas Holmberg
- Concord, California, USA
June 25, 2009