CONTACT CSI FOR MORE INFORMATION | CSIDESIGNS.COM | SALES@CSIDESIGNS.COM | 417.831.1411
PRE NUMBER INFORMATION
ALLOY UNS EN
NUMBER Cr Ni Mo N PRE
NUMBER
316L S31603 1.4404 16.5-18.5 10.0-14.5 2.0-3.0 0.1 23 Austenitic
S31603 1.4435 17.0-19.0 12.5-15.0 2.5-3.0 0.1 26 Austenitic
904L N08904 1.4539 19.0-23.0 23.0-28.0 4.0-5.0 0.1 34 Superaustenitic
2205 S32205 1.4462 22.0-23.0 4.5-6.5 2.5-3.5 0.14-0.20 35 Duplex
2507 S32750 1.4410 24.0-26.0 6.0-8.0 3.0-5.0 0.24-0.32 42.5 Duplex
254SMO S31254 1.4547 19.5-20.5 17.5-18.5 6.0-6.5 0.18-0.25 42 Superaustenitic
AL-6XN® N08367 -20.0-22.0 23.5-25.5 6.0-7.0 0.18-0.25 43 Superaustenitic
Maximum, unless range or minimum is indicated.
Values listed are primary elements only and are not complete chemical compositions as listed in specific product type specifications.
GENERAL NOTES:
The following are industry-accepted formulas. Other formulas may be used at the owner’s discretion.
(1) For stainless steels: PRE Number = %Cr + 3.3 [%Mo + 0.5(%W)] + 16(%N).
(2) For nickel alloys: PRE Number = %Cr + 1.5 (%Mo + %W + %Nb).
The Pitting Resistance Equivalent Number (PREN or PRE) is used as a guide for comparing and ranking a material’s
corrosion resistance. The PRE Number is calculated from a formula based on chemical composition. Although dierent
equations are used to calculate PRE Numbers for stainless steel and nickel alloys, the numbers can compare alloys for
ranking purposes. The relative values for some stainless steels and nickel alloys are shown in the following table. The
greater the number, the higher the resistance to pitting corrosion in chloride media.
In today’s market, there is a wide range of austenitic, superaustenitic, duplex, superduplex, and nickel-based alloys.
Besides corrosion resistance, other factors should be taken into consideration, such as commercial availability,
appearance, good mechanical properties, and fabrication characteristics.
ALLOY UNS EN
NUMBER Cr Ni Mo N PRE
NUMBER
625 N06625 2.4856 20.0-23.0 58 8.0-10.0 -41 Nickel
C-276 N10276 2.4819 14.5-16.5 57 15.0-17.0 -45 Nickel
C-22® N06022 2.4602 20.0-22.5 56 12.5-14.5 -46 Nickel
TABLE 2A: AUSTENITIC AND DUPLEX ALLOYS (NOTE 1)
TABLE 2B: NICKEL ALLOYS (NOTE 2)
