Summary for stainless steel pickling Discussion
acid cleaning (pickling) of stainless steel is discussed as a process that depends heavily on the stainless grade and prior treatment. Masoud Mostaghassi asked for the chemical composition and timing, but the replies did not give a single universal recipe. Fredi Yarcan answered a related plating question by outlining a different stainless-steel preparation cycle for plating copper, nickel, chrome, and silver: thorough cleaning, an activator bath for 30–60 seconds with current, rinsing, an optional chloride strike, another rinse, and a second activation step to achieve good bond. Umashankar Gupta then noted that pickling varies by stainless type and suggested common acid systems such as HCl + HNO3 + HF, HCl + HF, or H2SO4 at about 65°C. A later question from Ashish Grag asked which room-temperature mix is better for removing annealing scale, comparing nitric/sulfuric/hydrofluoric versus nitric/hydrochloric/hydrofluoric, but no answer is shown in the excerpt.
Q. I want to know the procedure of acid cleaning (pickling) of stainless steel — the composition of chemicals and durations. Can anybody answer my question?
Masoud Mostaghassi
tanks – Esfahan, IRAN
A. Dear Mr.Mostaghassi,
If you want to plate copper, nickel, chrome and silver over stainless steel cycle is as follows:
1) Clean stainless steel. Surface must be very clean.
2) Use activator bath (you can use a local company) for 30-60 seconds with current.
3) Water rinse.
4) Chloride Strike (optional)
5) Water rinse.
6) Use activation again (with or without current)
7) Water rinse
This above cycle will enable you to plate copper, nickel, chrome and silver over stainless steel with perfect bond.
Regards,
FREDI YARCAN
– Istanbul, Turkey
A. Masoud Mostaghassi,
There are so many types of pickling of s.s. depending on grades and treatment done on stainless. Normally HCl+HNO3+HF acid or HCl+HF acid or H2SO4 with temperature 65° C are used. Exactly what kind of s.s. do you want to pickle?
Umashankar Gupta
wire – Hyderabad, India
April 30, 2008
Q. I want to know, which mixture is better and why, to remove scaling after annealing of Stainless Steel.
1. nitric+sulfuric+hydrofluoric,
2. nitric+hydrochloric+hydrofluoric.
— both at room temperature
Ashish Grag
– Yamunanagar, India
May 17, 2012