Pickling stainless steel is a common treatment for stainless steel. It etches the surface of the stainless steel to reveal fresh material. In doing so, it removes contamination from machining, fabrication and welding operations. By removing contamination and scale, it improves the corrosion resistance and may remove corrosion sites.
It is common for drawings to call out "pickle and passivate". The pickling removes gross contamination and the passivation finishes the job - see below for information about the differences between pickling and passivation.
- ASTM A380
We can work to other specifcations, please contact us with your requirements.
Information for Designers
When to pickle?
The preparation of stainless steel is crucial to its corrosion resistance, so it is important to pickle and/or passivate after any cutting or abrasion. It is common practice to pickle after welding.
Do we need to passivate after pickling?
We would recommend passivation after pickling in all cases where corrosion resistance is important, which is most cases. Austenites (for example 300 series stainless steel) may perform well with only a pickle, but we still advise passivation as well. If passivation is required, it should always be performed after pickling. The cost pickling and passivation together is relatively low.
What is the difference between pickling and passivation?
Pickling lightly etches the stainless steel. By removing material it removes weld scale and debris that may be embedded beyond the reach of passivation. Passivation targets the iron only and encourages the formation of a passive layer. For machined parts where the risk of contamination is low, passivation will often be sufficient. When there is a higher risk of contamination or where there are welds, pickle and passivation together is often more suitable.