SS Surface Polishing

This article may answer your queries.

may i know what is pickling and passivation pls

Pickling is to process the metal in a weak acid so that the surface rusts and other foreign material are removed.

passivation is to create an uniform passive (oxide) layer on surface which will prevent normal attack by ambience (after picling the metal is totally naked and the highly prone to oxidation)

This is very brief, for the total theory, google, lot of literature available on net.

The pickling is kind of surface treatment to ensure the chromium layer is re-estabilished.

This is achived in pickling by removal of the corroded portion (on the surface) during the fabrication activities like Cutting with carbon steel cutting tool,welding & rough grinding etc.

The same is achived in the polishing also which nothing but mechanical pickiling process.

If, you want to still better pls. refer ASTM A380 standard which is pickiling process.

NOt required if you can cover whole surface by polishing.

Polishing is nothing but a mechinical pickling.