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ASTM B912

Standard Specification for Passivation of Stainless Steels Using Electropolishing

Specifies passivation of 200-, 300-, and 400-series and precipitation-hardening stainless steels by electropolishing.

ASTM InternationalRev. B912-26 (2026)Active
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What ASTM B912 specifies

ASTM B912 treats properly performed electropolishing as a stainless-steel passivation process. It covers substrate condition, cleaning, electropolishing, post-dip treatment, rinsing, and verification on 200-, 300-, and 400-series and precipitation-hardening stainless steels. It does not prescribe a universal electrolyte, current density, time, metal removal, reflectivity, or roughness result. Acceptance uses at least one agreed verification method: water immersion, humidity, salt spray, copper sulfate, or modified ferroxyl free-iron testing. Buyers must therefore state alloy, significant surfaces, required material removal or final dimensions, roughness if relevant, prohibited chemistry, and verification test.

Tests and the drawing call-out

Tests the document imposes

  • Water immersion
  • High-humidity exposure
  • Salt-spray exposure
  • Copper sulfate free-iron test
  • Modified ferroxyl free-iron test
  • Visual examination and agreed dimensional or roughness measurement

How to cite it

Drawing call-out

ELECTROPOLISH AND PASSIVATE STAINLESS STEEL PER ASTM B912, REMOVE <RANGE>, FINISH <Ra>, VERIFY BY <TEST>

Angle brackets mark the choices the drawing must make; every finish page shows a completed example.

Finishes specified to ASTM B912

Electropolishing on a machined partElectropolishingPassivation & electropolishingElectropolishing is controlled anodic dissolution that brightens, deburrs, and smooths stainless steel and other qualified alloys.CorrosionHardnessCost$$$

ASTM B912 — frequently asked

Does ASTM B912 set a metal-removal amount?

No. State removal or final dimensions separately when they matter.

Does B912 guarantee a mirror finish?

No. Electropolishing can smooth and brighten a surface, but the standard does not impose one reflectivity or Ra value.

Which passivation test should be used?

Choose a test compatible with the alloy and risk. Copper sulfate is not suitable for every stainless grade, so alloy review is essential.

ASTM B912 is copyrighted by ASTM International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗