 Pitting resistance equivalent number

The Pitting Resistance Equivalent Number (PREN) is a numerical value used to assess the resistance of stainless steel and other alloys to pitting corrosion, particularly in environments that are chloride-rich, such as marine settings. Pitting corrosion is localized corrosion that leads to the formation of small holes or pits in the metal. PREN is calculated using the formula: \[ \text{PREN} = %Cr + 3.