46041

We already electropolish 300 series; what will change for 200/400 series? [South Africa] 

August 5, 2007

Hi my name is brad and have been electropolishing 300 series stainless steels for years using a phosphoric/sulphuric combination. Recently the need to electropolish 200 and 400 series stainless steels has started. Will there be a major change in the chemical compositions of my tanks and if so how? Is there a chemical composition that will electropolish all 200,300 and 400 series grades?

Your response will be greatly appreciated

thanks
Brad

Brad Wilcocks
electropolishing plant owner - Kzn, South Africa

You can electropolish 2xx and 4xx in the same solution, but neither will polish as well as 3xx. Also watch carefully for possible etching and don't over polish. You may find a phosphoric/chromic solution works better for 2xx and 4xx.

Jeffrey Holmes, CEF - Spartanburg, SC, USA

I am of the opinion that 200 and 300 series stainless steels will polish very well using conventional sulphuric/ phosphoric acid mixes. However, 400 series stainlesses will present a problem due to the risk of included carbides. If you want to electropolish 400 series, you should ask your supplier for specialist solutions.

Trevor Crichton R&D practical scientist - UK

You can electropolish everything in one electrolyte to mirror finish, however you need to switch to acid-free electrolyte.

see picture attached of 430 stainless steel before and after electropolishing.

Anna Berkovich Russamer Lab Pittsburgh, Pennsylvania

I'd like to try electropolishing 316 stainless steel. What concentrations of Sulphuric and phosporic acids are typically used? Should there be any other additives? I currently do anodizing and am setting up a separate stainless steel tank to try the electropolishing in. Thank You in advance, John B.

John Best
- State College, PA, USA

75% by volume of 85% phosphoric + 25% by volume 66 Be' sulfuric, no water. Heavy buss and current density 50-100 asf. Temp 80-100F. Use ventilation.

Jeffrey Holmes, CEF - Spartanburg, SC, USA