Baking After Zinc Plating of Rc 40-42 Hardened Steel?
Q. I HAVE A SMALL METAL RING HEAT TREATED TO Rc 40/42. THEN THE PARTS ARE ZINC PLATED. MY QUESTION IS IF AFTER ZINC PLATING A BAKE IS NECESSARY, LIKE I AM HAVING DONE NOW ... OR NOT TO BAKE AS SOMEONE ELSE IS DOING ON THE SAME PART.WILLI KRUTOHOLOW
A. Necessary is a very relative question. At Rc 40, it certainly is a good idea for most parts. If you have zero legal liability for any conceiveable failure, then it is not required. If it is a straight short rod with generous radius on both ends, it is less necessary. If it has any amount of machining done on the raw stock, then bake relief is virtually mandatory.James Watts
- Navarre, Florida
A. Bake, known as "tempering" for heat treat purposes, is temperature specific x minimum time processed. A 40 Rc part has been heat treated well above 40 then tempered back to 40 by baking at a given temperature. Your heat treater should be able to provide you the bake temp of your product.
As long as your plater does not exceed the original bake temperature, the 40 Rc should not be affected.
Example: parts require 600 degrees for 1 hour temper to achieve 40 Rc, plater can bake up to 600 degrees for any amount of time without adversely affecting RC of the base material as long as his equipment [furnace] is accurate.Ron Landrette
plating equipment supplier - Bristol, Connecticut
Heat treat/tempering after zinc platingJanuary 13, 2015
Q. We have a steel pin that undergoes the following: it is heat treated, then plated with zinc, then heat treated again. Is there a specific reason why this item would undergo two heat treatments seperately before and after zinc plating?Tom Poole
Engineer - Armstrong, Iowa USA
A. Hi Tom. To what specification are these two heat treatments done? My first suspicion is that you are using the phrase "heat treatment" in the very broad sense of the part being heated up in any fashion. Hardened steel often/usually (depending on hardness) requires baking for hydrogen embrittlement relief after operations that expose it to atomic hydrogen, such as pickling or plating. The temperature of such baking processes is low enough to not affect the hardness of the steel, and many people would not use the terms "heat treat" or "tempering" for this hydrogen relief baking.
If you have some details, people will be able to comment more specifically. Or, if you think I'm on the right track, put "hydrogen baking" into the search engine at the top of the page for more details. Thanks.
Ted Mooney, P.E.
Pine Beach, New Jersey
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