Passivation treatment for Inconel 625 1

[AnsAvi]

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

 

[EdStainless]

You require them, buy copies and read them.
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

 

[pradipgoswami]

Both ASTM A380 and A967 are applicable for stainless steels. Also as previously stated by Ed Stainless ASTM B446 does not mention anything about pickling and passivation of alloy 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_625_E.pdf

https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_Alloy_625.pdf

Thanks.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299