The authoritative public forum
  for Metal Finishing since 1989
-----

Test for nitriding on steel

2004

Hi,

I would like to know what methods can be used to verfy or test for nitriding on a steel. I an seeking to use a non-distructive testing method to verify if the surface of the component was nitrided or not. Thermospray is also used for surface hardening and how can one differentiate between the two surfaces?

Regards,

August Pandey
Workshop - Johannesburg, Gauteng, South Africa

---

2004

A simple method is to supply a coupon of the same base material to be nitrided together with your parts. Then you can cut it, attack w/suitable reagent and see under a microscope the white layer, depth, check microhardness, etc. To distinguish from thermospray a thorough polish on a concealed area will reveal thermosprayed surface to be porous while nitrided surface will be sound and smooth. G. Marrufo-Mexico

P.S. There are new thermospray guns capable of very low porosity (High output HVOF claim less than 1%) but the microstructure will show very different from nitriding

Guillermo Marrufo
Monterrey, NL, Mexico