The pre-electropolish cleaning step shall be accomplished using any organic solvent or non-etching detergent cleaner.

The electropolish solution shall be composed of a relatively concentrated acid mixture of either a glycolic-sulfuric acid or phosphoric-sulfuric acid composition. However, it is noted that a rather large number of different electropolish formulations are commercially available. Exceptions to the above acid solution compositions must be submitted to ES4 materials engineering for approval.

The specific gravity of the solution shall be in compliance with that which is specified by the solution vendor at the 170-180F operating temperature when the recommended current density is used. The specific gravity of this solution shall be checked with a hydrometer every two weeks. Immediately after checking the solution’s specific gravity, a sample of the chemical bath shall be titrated to determine the correct percentages of dissolved solids. The electropolish solution shall be maintained between 2.5% and 3.5% iron. If these limits are not met, the solution shall be removed and replaced.

If stainless steels 420, 440A, 440B, or 440C are to be electropolished, they must first be annealed at 300-700F in order to avoid pickling cracks. If components have been heat treated, they may require a wet or dry blasting procedure to remove the scale.

Thank you very much for your answer.

Next, I had another question.

Can you express the composition of the proposed acids in percentages?

I have now tested 440C for electropolish alloy of 60% phosphoric acid and 40% sulfuric acid, but I did not answer. Do you have any suggestions?

Typical electropolishing solution consist of an equal volume mixture of 96% mass fraction sulfuric acid and 85% orthophosphoric acid, the operating condition are as follows :

current density: 4 A/dm2 to 25 A/dm2

temperature : 40 C to 75 C

time : 2 min to 20 min

cathodes : stainless steel, copper, lead

Hi raghd

Thank you for giving me you time and answering my question.

I wish you success.

you are welcome ... best wishes