Wrap-up
86%
Vendor selection and QC sign-off — separating real nitriding houses from job shops
The 30-minute phone audit, the on-site signal list, the first-article QC checklist, and the small-shop exceptions that pencil out anyway.
Tying it together
Closing the course
The Lesson 1 framing, two certificates with the same word on them describing very different cases, is the visible part of the four levers: process family, temperature, time, atmosphere ratio. Eleven lessons later, every lever has a name, a setpoint, a measurement, and a way to verify it on a certificate. The eight-element callout from Lesson 11 turns a vague "nitride to 0.020 case" into a controllable process. The eight-question phone audit turns a vendor pitch into a tier classification. The first-article checklist turns a certificate into evidence.
Pick one current part with a vague "nitride" callout on the drawing. Rewrite it with the eight spec elements from Lesson 11. Send it to a candidate vendor with the eight-question audit on the cover page. Run the first article through the checklist in the section above before signing off on production.
Sources
- SAE International, AMS 2759/10B: Automated Gaseous Nitriding Controlled by Nitriding Potential. https://www.sae.org/standards/content/ams2759/10b/
- SAE International, AMS 2759/12: Gaseous Nitrocarburizing, Automatically Controlled by Potentials. https://www.sae.org/standards/content/ams2759/12/
- AIAG, CQI-9 Special Process: Heat Treat System Assessment (referenced framework for automotive heat-treat audits).
- Performance Review Institute, Nadcap Heat Treating Audit Criteria (AC7102 series).
- ASTM International, E384 Standard Test Method for Microindentation Hardness of Materials. https://www.astm.org/news/microindentation-hardness-mj10
- ISO, 18203:2016 Steel — Determination of the thickness of surface-hardened layers. https://www.iso.org/standard/61748.html
- Advanced Heat Treat Corp, Evaluating Case Depth for Case Hardening Treatments. https://www.ahtcorp.com/articles/blog/evaluating-case-depth-for-case-hardening-treatments/
- Pye, D. Practical Nitriding and Ferritic Nitrocarburizing, ASM International, 2003. https://dl.asminternational.org/technical-books/monograph/172/Practical-Nitriding-and-Ferritic-Nitrocarburizing