ISO/TR 15608 Material Group 10.3:
Austenitic ferritic stainless steels (Lean–Duplex) with Ni ≤ 4 %
What are Lean-Duplex steels?
Lean-Duplex steels are low Ni-alloyed, the duplex microstructure contributes to the high strength. Lean duplex steels are suitable for less aggressive conditions. Lean duplex stainless steels are a subset of duplex stainless steels that are formulated with lower amounts of expensive alloying elements, like nickel and molybdenum, while still maintaining good corrosion resistance and higher strength than conventional austenitic stainless steels. In duplex stainless steel, N is an important element that is used extensively for the enhancement of PREN (22 – 27), stabilisation of the austenite phase, and improvement of strength.
For comparison: Austenitic steels (PREN = 24-25); Lean Duplex steels (PREN=21-32), Standard Duplex steels (PREN =32-40); Super Duplex steels (PREN = 40-48); Hyper Duplex steels (PREN >48).
Note: There is no exact definition for this classification.
The pitting corrosion resistance is better than that of austenitic AISI 304 (EN 1.4307) and can reach the level of AISI 316L (EN 1.4404).
Weldability of Lean Duplex steels
Duplex stainless steel grades generally have good weldability and they can be welded using most of the welding methods used for austenitic stainless steels. In particular, N is very effective in maintaining the austenite phase of welds. Typical recommended heat inputs are 15-20 KJ/cm with a max. 150 °C interpass temperature. Nitrogen to the shielding gas and use of nitrogen-based backing gas can further improve the austenite formation and make the weld metal more resistant to pitting. It is not recommend pre- or post-welding heat treatments. Only complete solution annealing heat treatment may be considered.
Typical material in group 10.3
| Name/Grade/Type | Number | Standard | Product | Alloy | Remarks |
|---|---|---|---|---|---|
| – S32003 S32003 S32003 | S32003 S32003 S32003 S32003 | ASTM A-240 ASTM A-789 ASTM A-790 ASTM A-928 | Plate Smls. and welded tube Smls. and welded pipe Welded pipe | ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| X2CrNiN22-2 – – – – | 1.4062 S32202 S32202 S32202 S32202 | EN 10088-2 ASTM A-479 ASTM A-789 ASTM A-790 ASTM A-815 | Plate Bar Smls. and welded tube Smls. and welded pipe Fitting | – ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| X2CrMnNiN21-5-1 – – – – – – | 1.4162 S32101 S32101 S32101 S32101 S32101 S32101 | EN 10028-7 ASTM A-240 ASTM A-479 ASTM A-789 ASTM A-790 ASTM A-815 ASTM A-928 | Plate Plate Bar Smls. and welded tube Smls. and welded pipe Fitting Welded pipe | EN ISO 21009-1 ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC ASME BPVC | |
| – – | S82011 S82011 | ASTM A-789 ASTM A-790 | Smls. and welded tube Smls. and welded pipe | ASME BPVC ASME BPVC | |
| – | S82012 | ASTM A-240 | Plate | ASME BPVC | |
| – | S82031 | ASTM A-240 | Plate | ASME BPVC |
Read More
Standard Duplex steel: ISO/TR 15608 Group 10.1
Super Duplex steel: ISO/TR 15608 Group 10.2