Super Duplex UNS S32750

Super Duplex UNS S32750 Technical Information

Overview

Super Duplex is an austenitic ferritic Iron Chromium-Nickel alloy with Molybdenim addition. It has good resitance to pitting, a high tensile strength and higher resistance to stress corrosion cracking at moderate temperatures to that of conventional austenitic stainless steels.

Super Duplex is a material having an approximate equal amount of austenite and ferrite. These combine excellent corrosion resistance with high strength. Mechanical properties are approximately double those of singular austenitic steel and resistance to stress corrosion cracking is superior to type 316 stainless steel in chloride solutions. Super Duplex material has a ductile / brittle transition at approximately -50°C. High temperature use is usually restricted to a maximum temperature of 300°C for indefinite use due to embrittlement.

Benefits

There are several benefits of Duplex including:

  • High Strength
  • High resistance to pitting, crevice corrosion resistance
  • High resistance to stress corrosion cracking, fatigue and erosion
  • Excellent resistance to Chloride stress corrosion cracking
  • High Thermal conductivity
  • Low coefficient of thermal expansion
  • Low thermal expansion and higher heat conductivity than Austenitic steels
  • Good Sulfide stress corrosion resisitance
  • High energy absorption
  • Good workability and weldability

Applications

Pipe – ASTM A790

The method of manufacture can be either seamless or automatic welding, with no addition of filler metal. Pipe may be hot or cold finished but must always be furnished in the heat treated condition.

BUTT WELD – ASTM A815

This class covers the class of WP, made up of 4 categories and meet the requirements of ANSI B16.9. Pressure ratings are the same compatability of matching pipe.

Categories :-

  • WP-S : Seamless Construction
  • WP-W : Welded Construction where construction welds are radiographed
  • WP-WX : Welded Construction where all welds are radiographed
  • WP-WU : Welded Construction where al welds are Ultrasonically Tested.

Flanges ASTM A182

Material forged as near as practical to the specified size and shape. Forged or Rolled Bar may be used without additional hot working for small cylindrical shaped parts below 4” NB. Flanges of any description cannot be machined directly from Forged or Rolled Bar.

Technical Details

CHEMICAL COMPOSITION (All values are maximum unless stated otherwise)
%C %Cr %Ni %Mo %Mn %S %P %Si %N
0.03 24.0-26.0 6.0-8.0 3.0-5.0 1.0 0.02 0.035 0.80 0.24-0.32
MECHANICAL PROPERTIES
Yield Strength Tensile Strength Elongation (Minimum) Reduction of Area (Minimum) Hardness (Maximum)*
(Ksi) (Mpa) (Ksi) (Mpa)     (Bhn)
80 550 116 800 15 310

* (N.A.C.E. MR-01-75 latest revision may limit hardness in certain applications)

PREn (PITTING RESISTANCE EQUIVALENT) – (%Cr) + (3.3 x %Mo) + (16 x %N)

HEAT TREATMENT: SOLUTION ANNEALED AT 1100 DEG C – 1140 DEG C WATER QUENCH

EQUIVALENT GRADES
UNS BS EN SWEDEN SS GERMANY DIN SANDVIK +
32750 1.4410 2328 X2 CrNiMoN 25.7.4 SAF 2207