Is the cause of blue spots in stainless steel blue spot detection passivation or incomplete pickling or iron ions? Simply put, it's not cleaned by pickling, is it?

Hello, landlord.

I have read your question three times, and now I will answer your question.

What is the blue dot test? Blue spot detection: If the passive film on the surface is imperfect or polluted by iron ions, there will be free iron ions, which can react. Blue spots appear on the workpiece within 30 seconds, indicating that the passivation film is not completely formed. That's NG. (Generally speaking, it is to check whether the passivation film is complete and dense)

Stainless steel is passivated by pickling first, and then tested by blue dot.

Provide stainless steel pickling passivation solution with blue dot detection. Pay attention to the username. Ms. Dai.

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