Passivation treatment for Inconel 625
Passivation treatment for Inconel 625
(OP)
Hi,
We have a spec that calls out for ASTM B446 passivation on IN-625 alloy. We recently changed our supplier and I realized that they only adhere to ASTM A380 and A967 for passivation. They refuse keeping to B446 standard. Can someone help me in informing what the differences are between these standards and whether I should be concerned?
Thanks
We have a spec that calls out for ASTM B446 passivation on IN-625 alloy. We recently changed our supplier and I realized that they only adhere to ASTM A380 and A967 for passivation. They refuse keeping to B446 standard. Can someone help me in informing what the differences are between these standards and whether I should be concerned?
Thanks





RE: Passivation treatment for Inconel 625
Sorry but if you are invoking a specification you must know what it is.
B446 is the rod and bar spec, the word passivation does not appear in this spec at all.
How did you approve a new vendor?
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P.E. Metallurgy, Plymouth Tube
RE: Passivation treatment for Inconel 625
To the best of my knowledge there are "Yes & No" with respect to Pickling and passivation of Nickel alloys. The acid bath(HNO3+HF) used for pickling requires very close control and in cases pickling could be counter productive. Nickel alloys are difficult to pickle.
You need to do more research before jumping on to passivation requirements.
Some useful resourecs :
http://www.nyk.co.jp/en/pdf/products/alloys/NAS_62...
https://www.vdm-metals.com/fileadmin/user_upload/D...
Thanks.
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299