BLACK OXIDE ON 4140 PH

[engiNERD77]

WILL THE A CALL OUT FOR BLACK OXIDE GIVE THE SURFACE RESISTANCE TO RUSTING?

 

[arunmrao]

No capital letters please.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

Capital letters or not, I can't make sense of the post.

 

[djhurayt]

black oxide will only provide minimal rust resistance

 

[EdStainless]

often black oxide is then treated with oils or waxes in order to provide some short term corrosion resistance.

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P.E. Metallurgy, Plymouth Tube

 

[engiNERD77]

Thanks guys! Pretty much what I had read about.

 

[tbuelna]

engiNERD77,

You didn't provide the process spec for your black oxide coating, but MIL-DTL-13924 is a commonly used one. Your 4140 Pre Hardened material would use MIL-DTL-13924 class 1. If the final material hardness is >Rc39, you will also require hydrogen embrittlement relief treatment.

I would highly recommend taking some time to educate yourself a bit about the black oxide process and the coating characteristics. Understanding the process steps, quality assurance requirements, specifying supplementary treatment, etc. will be very helpful when specifying the coating on your engineering documentation and preparing vendor work orders so that your delivered product is exactly what you want. MIL-HDBK-205 is an excellent reference on the subject.