Stainless Steel / 303 SEL ANN

303SE is an austenitic stainless steel melted as AOD melt type and offers excellent machinability. This grade is a modified version of 303 with a selenium addition in place of sulfur which allows for excellent machinability. Selenium produces a better surface finish. This 18-8 chromium-nickel stainless steel is modified by the addition of selenium or sulphur, as well as phosphorus, to improve machinability and non- seizing properties. 303 is non-magnetic in the annealed condition and not hardenable by heat treatment. Stainless Steel 303 is widely used in the screw machine industry, as well as for use in shafts, valves and fittings. Stainless Steel 303 is not recommended for vessels containing gases or liquids under high pressure. (UNS:S30323)

Chemical Makeup

Element Min Max
Carbon, C 0.15
Manganese, Mn 2
Silicon, Si 1
Sulfur, S 0.04
Phosphorus, P 0.12 0.17
Chromium, Cr 17 19
Nickel, Ni 8 10
Copper, Cu - 1
Molybdenum, Mo - 1
Selenium, Se 0.15 0.4

Common Applications

  • Aerospace Aerospace
  • Industrial Industrial


  • Excellent Machinability
  • Corrosion Resistance
  • Nongalling Properties

We stock 303 SEL ANN to the following specifications:

  • AMS-5640 TYPE 2
  • AMS-5641
  • ASTM-A-320 GRD B8F CL. 1
  • ASTM-A-484
  • ASTM-A-582
  • MIL-S-7720
  • MIL-W-52263
  • QQS-763C
  • QQS-764 B

Click on a cross-section to see the sizes we stock:

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