S-Phase Nitriding: Retaining Corrosion Resistance in Stainless Steels

posted On Thursday, September 19, 2019 in Blog

UltraGlow technology is now a very well-developed process that can be carried out by either carburizing or nitriding; such processes produce a so-called "S-phase."

Austenitic Stainless Steels

For instance, a stainless steel component made of austenitic stainless steel such as 304 or 316, UltraGlow Nitriding will saturate the surface of the component of the steel with nitrogen or both carbon and nitrogen and then form an expanded (S-phase) layer. When austenite is saturated with a significant amount of nitrogen or carbon, which expand its lattice, the S-layer forms.

The layer of this type can be formed in stainless steels such as 304, 316, 2205 and others. The S-phase layer has enhanced corrosion resistance. It is approximately 10-15 micrometers thick (or 0.004-0.006 inches) and is extremely hard (more than 1000 Vickers). This layer is resistant to corrosion in many environments. It is also resistant to cavitation and erosion, as well as to the tribological or corrosive interactions. Oil, gas and/or marine  industries find this surface treatment extremely beneficial as it assists in the prevention of corrosion.

Photo micrograph of 2205 duplex stainless steel showing
the S-phase formed during combined carburizing/nitriding cycle.

Interested in learning more about S-Phase Nitriding? CLICK HERE

1. corrosion resistance
2. nitriding
3. stainless steel