Duplex Pitting Resistance Equivalent Number
Duplex Pitting Resistance Equivalent is a value used to evaluate the pitting corrosion resistance of duplex and superduplex steels. It considers the mass fractions of chromium, molybdenum, and nitrogen. This value helps in selecting suitable materials for marine applications.
Physico-Chemical Mechanism of Action
The Duplex Pitting Resistance Equivalent (DPRE) is a calculated index that quantifies the pitting corrosion resistance of duplex and super duplex stainless steels. It is based on the mass fractions of chromium (Cr), molybdenum (Mo), and nitrogen (N). These elements influence the corrosion resistance of the steel by forming a dense protective layer on the surface.
Metallurgical Relevance & Welding Risks
A too low DPRE value can lead to increased susceptibility to pitting corrosion. This can result in cracking and failure in marine environments where saltwater and chlorides are common. When selecting materials, it is critical to choose a DPRE value that meets the specific requirements of the application.
Workshop Practice & Instructions
To calculate the DPRE value of a steel, the mass fractions of chromium, molybdenum, and nitrogen are determined. The calculation is done according to a set formula sheet included in the manufacturer's material specification. When selecting a suitable steel for marine applications, a DPRE value of at least 40 should be chosen to ensure adequate pitting corrosion resistance.