Acid cleaning or Picking & Passivation 1

[whila]

Hi Everyone.

I`ve already read many threads and kind reply for passivation, but i have still query for differece between acid cleaning and pickling & passivation as belows.

1. Is acid cleaning same as pickling & passivation ?
Furthermore, can i know how ASTM 380 code explains acid cleaning and passivation?

2. If no.1 is same, does it mean that acid cleaning and picklin & passivation has same procedure and same chemical material are applied ?

I appreciated if you reply for me.
Many thanks.

 

[moltenmetal]

When I hear "acid cleaning" I think merely removing deposits from the surface of finished articles- deposits associated with use rather than manufacture.

Pickling is an acid etch process by which the surface oxide layer (mill scale, welding heat tint etc.) and any foreign bodies (embedded particles from rolls for forming dies etc.) are removed from the surface, along with a certain amount of the parent material.

Passivation is the re-growth of the passive oxide layer on the surface of the material. It can be natural, resulting from a period of exposure to air, or it can be enhanced by means of exposure to particular conditions in solution- either as part of the pickling process or as an entirely separate step.

What pre-cleaning, acid solution or paste composition, temperature, time of exposure etc. is necessary depends on what material you're processing and what you're trying to do to it.

I don't have a copy of ASTM 380 so have no idea what it covers. Suggest you buy and read it.

 

[babouic]

ASTM A380 : Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems
As it is written, A380 is only related to Stainless Steel where section 6.1.11 and Annex A2 describe acid cleaning and section 5.2.1 & Annex A1 recommendation for pickling (acid descaling).

 

[metengr]

I would suggest you visit the site below and do some of your own research. It is not that difficult.

http://www.outokumpu.com/en/Products/Tools/Pages/default.aspx

 

[whila]

Thank you for your kind reply