**1.2 About this book chapter**

This chapter will not cover the fundamentals of corrosion – we assume that the reader will have a basic knowledge about the principles of corrosion. This paper will provide an overview about the role of nitrogen related to corrosion of stainless steels. Since a lot of

Corrosion Resistance of High Nitrogen Steels 57

Fig. 2. Schematic design of a pressure electro slag remelting furnace (PESR).

alloy dependent)

elements.

The physical fundamentals of nitrogen pick up are specified over the Sievert square root law, accordingly that the nitrogen solubility is a function of pressure and temperature:

With pN2: Nitrogen partial pressure over melt in bar, k: Material constant (temperature and

In real systems, the actual solubility is additionally codetermined through the alloy composition. Thermodynamic activities are used to describe the effect of the individual

> *Fe X X N N*

[% ] [% ] *Fe*

<sup>2</sup> [% ] *N kP <sup>N</sup>* (1)

*<sup>N</sup> N p <sup>f</sup>* (2)

2

results have been published to date, common knowledge will summarized and topped up with own data and experimental results.

Finally, some typical HNS grades will be discussed with regards to their industrial application.

Fig. 1. Mechanical properties in dependency of different nitrogen concentrations after quenching at 1150°C, 2h in water. [Rashev et al.,2003]
