ISO/TR 15608 Material Group 10.2 :
Austenitic ferritic stainless steels (Super Duplex) with Cr > 24,0 % and Ni > 4 %
Super Duplex Steels ISO/TR 15608 Material Group 10.2
The super duplex grades are used widely across all industry sectors. The primary factors that drive the use of duplex stainless steels are their improved stress corrosion cracking resistance and the potential to reduce cross sections in high-stress or high-pressure applications and tank construction. As with the other stainless steel families, the duplex grades have a range of corrosion resistance and can be divided into subgroups, depending on alloying content.
The super duplex grades typically contain 24-26% chromium, 6-8% nickel, 3-5% molybdenum, and 0.24-0.27% nitrogen. Grades in this category are used widely across all industry sectors and 2507 (S32550) has become by far the most widely used duplex grade. The 2507 grade has a yield strength that is more than twice that of Type 316 and a pitting and crevice corrosion resistance that is similar to Type 904L austenitic stainless steel.
An empirical relationship called the Pitting Resistance Equivalent Number (PREN) has been developed to relate a stainless steels composition to its relative pitting resistance in chloride solutions.
For comparison: Austenitic steels (PREN = 24-25); Lean Duplex steels (PREN=21-32), Standard Duplex steels (PREN =32-40); Super Duplex (PREN = 40-48); Hyper Duplex steels (PREN >48).
Note: There is no exact definition for this classification.
Applications for standard duplex grades include tanks, piping, process vessels and structural applications.
Weldability of Super Duplex Steels ISO/TR 15608 Material Group 10.2
Duplex stainless steels have a very good cracking resistance due the high ferrite content, hot cracking is rarely a consideration when welding these steels. Therefore the problem of most concern in duplex steels are associated with the heat effect zone (HAZ) of welds. The HAZ problems can be loss of corrosion resistance , toughness, or post-weld cracking. To avoid these problems, the welding procedure should focus an minimising total time at temperature in the “red hot” range rather than managing the heat input for any one pass.
Preheating: As general guideline, the max. interpass temperature is limited to 100°C.
PWHT: Is not needed for Duplex stainless steels
Any post weld heat treatment should include full solution annealing followed by water quenching.
Typical material in group
| Name/Grade/Type | Number | Standard | Product | AISI | Remarks |
|---|---|---|---|---|---|
| X2CrNiMoN25-7-4 X2CrNiMoN25-7-4 X2CrNiMoN25-7-4 X2CrNiMoN25-7-4 X2CrNiMoN25-7-4 X2CrNiMoN25-7-4 S32750 F53 S32750 S32750 2507 S32750 – | 1.4410 1.4410 1.4410 1.4410 1.4410 1.4410 S32750 S32750 S32750 S32750 S32750 S32750 S32750 | EN 10028-7 EN 10272 EN 10216-5 EN 10217-7 EN 10222-5 EN 10253-4 ASTM A-240 ASTM A-182 ASTM A-789 ASTM A-790 ASTM A-928 ASTM A-479 ASTM A-815 | Plate Bar Smls. tube Welded tube Forging Fitting Plate Forging Smls & welded tube Smls & welded pipe Welded pipe Bar Fitting | EN 13445-2 & EN 13480-2 & EN ISO 21009-1 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| GX2CrNiMoN25-7-3 | 1.4417 | EN 10213 | Steel cast., pressure purposes | EN 13445-2 | |
| F54 S39274 S39274 | S39274 S39274 S39274 | ASTM A-182 ASTM A-789 ASTM A-790 | Forging Smls & welded tube Smls & welded pipe | ASME BPVC ASME BPVC ASME BPVC | |
| 2A 2A | J93345 J93345 | ASTM A-890 ASTM A-995 | Casting Casting – pressurised parts | ASME BPVC ASME BPVC | |
| 3A 3A | J93371 J93371 | ASTM A-890 ASTM A-995 | Casting Casting – pressurised parts | ASME BPVC ASME BPVC | |
| GX2CrNiMoN26-7-4 5A 5A | 1.4469 J93404 J93404 | EN 10213 ASTM A-890 ASTM A-995 | Steel cast., pressure purposes Casting Casting – pressurised parts | – CE3MN CE3MN | EN 13445-2 ASME BPVC ASME BPVC |
| X2CrNiMoCuWN25-7-4 X2CrNiMoCuWN25-7-4 X2CrNiMoCuWN25-7-4 X2CrNiMoCuWN25-7-4 X2CrNiMoCuWN25-7-4 S32760 F55 S32760 S32760 – – | 1.4501 1.4501 1.4501 1.4501 1.4501 S32760 S32760 S32760 S32760 S32760 S32760 | EN 10028-7 EN 10272 EN 10216-5 EN 10217-7 EN 10253-4 ASTM A-240 ASTM A-182 ASTM A-789 ASTM A-790 ASTM A-928 ASTM A-815 | Plate Bar Smls. tube Welded tube Fitting Plate Forging Smls & welded tube Smls & welded pipe Welded pipe Fitting | EN 13445-2 & EN 13480-2 & EN ISO 21009-1 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| X2CrNiMoCuN25-6-3 X2CrNiMoCuN25-6-3 X2CrNiMoCuN25-6-3 X2CrNiMoCuN25-6-3 255 F61 S32550 S32550 | 1.4507 1.4507 1.4507 1.4507 S32550 S32550 S32550 S32550 | EN 10028-7 EN 10272 EN 10216-5 EN 10253-4 ASTM A-240 ASTM A-182 ASTM A-789 ASTM A-790 | Plate Bar Smls. tube Fitting Plate Forging Smls & welded tube Smls & welded pipe | EN 13445-2 & EN 13480-2 & EN ISO 21009-1 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| GX2CrNiMoCuN25-6-3-3 CD4MCuN 1B 1B | 1.4517 1.4517 J93372 J93372 | EN 10213 EN 10283 ASTM A-890 ASTM A-995 | Steel cast., pressure purposes Steel casting Casting Casting – pressurised parts | – – CD4MCuN CD4MCuN | EN 13445-2 & EN 13480-2 – ASME BPVC ASME BPVC |
| 1C | J93373 | ASTM A-890 | Casting | – | ASME BPVC |
| GX3CrNiMoCuN24-6-5 | 1.4573 | EN 10213 | Steel cast., pressure purposes | – | |
| GX3CrNiMoCuN24-6-2-3 | 1.4593 | EN 10213 | Steel cast., pressure purposes | – | |
| 7A 7A | J93379 J93379 | ASTM A-890 ASTM A-995 | Casting Casting – pressurised parts | ASME BPVC ASME BPVC | |
| CD3MWCuN 6A 6A | J93380 J93380 J93380 | ASTM A-351 ASTM A-890 ASTM A-995 | Casting Casting Casting – pressurised parts | ASME BPVC ASME BPVC ASME BPVC |
Lean Duplex steel: ISO/TR 15608 Group 10.3
Standard Duplex steel: ISO/TR 15608 Group 10.1
Suitable Standard-Duplex and Super-Duplex steels for Pressure Equipments
