Duplex Plate grades vary mainly based on the chromium content in them. The chromium content is denoted by a PREN number. The number corresponds to chromium percentage in the composition. The different grades have different levels of chromium. The lean grade duplex steel uses the least amount of chromium and therefore the PREN numbers are low. The standard duplex uses medium level of chromium and it has a medium range of PREN numbers usually 28 to 38. The super duplex is the one that uses chromium the most, ranging from 38 to 45. The more the chromium addition, the less the corrosion risk. With the addition of chromium, the strength goes down. So the lean duplex plate will be of high strength but less corrosion resistance compared to the super duplex.
The high corrosion resistance is used in industries that deal with high corrosion environments, such as water desalination plants and sea water applications. There are other industries and applications that require strength the most. Industries like the transportation, construction and architecture require strength the most. So these use the lean grade duplex stainless steel plate for their needs. The standard duplex grade on the other hand has a balance of both strength and corrosion resistance. Therefore it is the most widely used types of duplex steel. The duplex stainless steel sheet price varies depending on the grade needed, the sheet size, the sheet thickness and other market fluctuations. Since the standard duplex is the most used, the availability and prices are comfortable.