Nital Etch Non-destructive Testing Method

Nital Etch, also known as Surface Temper Etch and Temper Etch, is a non-destructive test that is used to determine if overheating has occurred in a part (after final heat treat) by abusive machining or grinding that will adversely affect the required properties of the part in question. It is used specifically to look for:

  • Overtempering
  • Localized Re-tempering
  • Re-hardening
  • Localized discontinuous carburization
  • Decarburized surface layer

Etching will detect surface variations where softer tempered materials will darken (burn) faster than harder areas on machine and apparatus parts such as shafts, gears, splines, bearings, and journals.

MTC Nital Etch Laboratory Inspection Service

At Element, we have a complete in-house capability of equipment, chemicals, procedures, qualified personnel, waste treatment, environmental related permits, and industry certifications to accomplish high-quality nital etch processing.

We provide the following services:

  • Nitric Acid based standard processing with or without a post processing Bake cycle.
  • Preparatory Hydrochloric processing for Tool Steel followed by standard processing.
  • Ammonium Persulfate based processing without a post processing Bake cycle (this is our alternative process).

Element has an in-house bake capability that is certifiable to AMS 2759/9.

Element is also approved to perform the following nital etch related specifications:

  • MIL-STD-867
  • AMS 2649
  • AF5236
  • HPS3002
  • CEIM-5
  • EIM Code 5
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