Special stainless steels
When 316L is not enough: stainless alloys for chlorides, acids, high pressure and high strength, with standards, composition and properties of each one.
Special stainless steels: alloys supplied by Dustre
Forms: Bar, Plate, Forging and flange, Casting, Wire, Pipe, Fitting. Click an alloy to see standards by form, composition, properties and equivalents.
| Material | UNS | W.Nr. / EN | Forms |
|---|---|---|---|
| 15-5PH – UNS S15500 (XM-12)Precipitation-hardening stainless · Martensitic precipitation-hardening stainless steel (Cr-Ni-Cu) | S15500 | 1.4545 | Bar, Plate, Forging and flange, Casting |
| 17-7PH – UNS S17700 (Type 631)Precipitation-hardening stainless · Semi-austenitic precipitation-hardening stainless steel (Cr-Ni-Al) | S17700 | 1.4568 | Bar, Plate, Forging and flange, Wire |
| 254 SMO / F44Super austenitic stainless · 6Mo super-austenitic stainless steel with nitrogen | S31254 | 1.4547 | Bar, Plate, Pipe, Forging and flange, Fitting |
| A-286 / Alloy 660Precipitation-hardening stainless · Precipitation-hardenable Fe-Ni-Cr superalloy | S66286 | 1.4980 | Bar, Plate, Forging and flange |
| 17-4PH stainless steel – UNS S17400 (ASTM A564 Type 630)Precipitation-hardening stainless · Martensitic precipitation-hardening stainless steel (Cr-Ni-Cu-Nb) | S17400 | 1.4542 | Bar, Plate, Forging and flange, Casting |
| 904L stainless steelSuper austenitic stainless · Low-carbon Ni-Cr-Mo-Cu super-austenitic stainless steel | N08904 | 1.4539 | Bar, Plate, Pipe, Forging and flange |
| Alloy 20 (Carpenter 20)Super austenitic stainless · Niobium-stabilized Fe-Ni-Cr-Mo-Cu alloy | N08020 | 2.4660 | Bar, Plate, Pipe, Forging and flange, Fitting |
| Alloy 28Super austenitic stainless · 27Cr-31Ni-3.5Mo-Cu super-austenitic stainless steel | N08028 | 1.4563 | Bar, Plate, Pipe |
| 17-4PH round bar – ASTM A564 Type 630 / AMS 5643Precipitation-hardening stainless · Rolled or forged precipitation-hardening stainless bar, condition A or H1150 | S17400 | 1.4542 | Bar, Forging and flange |
| Duplex 2205 / F60 / S32205Duplex · All standards by product form | S32205 | 1.4462 X2CrNiMoN22-5-3 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Duplex F51 / S31803Duplex · All standards by product form | S31803 | 1.4462 X2CrNiMoN22-5-3 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Ferralium 255 / F61Super duplex · 25Cr-6Ni-3.5Mo-2Cu-N super duplex stainless steel | S32550 | 1.4507 | Bar, Plate, Pipe, Forging and flange |
| 329 stainless steelDuplex · First-generation 25Cr-4Ni-1.5Mo duplex stainless steel | S32900 | 1.4460 | Bar, Plate, Pipe, Forging and flange |
| Super duplex 2507 / F53 / S32750Super duplex · All standards by product form | S32750 | 1.4410 X2CrNiMoN25-7-4 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Super duplex Zeron 100 / F55 / S32760Super duplex · All standards by product form | S32760 | 1.4501 X2CrNiMoCuWN25-7-4 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
Did not find the alloy? See all materials or ask the technical team.
About special stainless steels
Three groups cover most severe cases. Duplex and super duplex (2205, F51, F53, F55) combine ferrite and austenite: twice the yield strength of 316L and high resistance to pitting and stress corrosion cracking in chlorides, with PREN from 35 to over 40. Super austenitics (904L, 254 SMO, Alloy 20) carry more nickel and molybdenum for sulfuric and phosphoric acid and seawater. Precipitation-hardening grades (17-4PH, 15-5PH, 17-7PH) reach 1,300 MPa after aging, for shafts, gears and aircraft parts.
Dustre keeps these alloys in stock as bar and forging and performs the heat treatment (solution annealing, aging) and the tests in its own laboratory.
See also
Frequently asked questions
Duplex or super duplex?
By PREN and temperature: 2205 (PREN ≈ 35) handles most chlorides up to about 60 °C; F53 and F55 (PREN ≥ 40) for hot seawater, H2S and wells. Calculate the PREN of your composition in the calculator.
Is 17-4PH really stainless?
Yes, a precipitation-hardening martensitic stainless (Cr 15–17.5 %, Ni 3–5 %, Cu 3–5 %). It resists like 304 in atmosphere and fresh water, with much higher strength.
