Alloy 32760 (UNS S32760)
Alloy 32760 is a super duplex stainless steel supplied in the hot worked and solution annealed condition. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. The higher chromium, molybdenum and nitrogen contents result in a Pitting Resistance Equivalent number (PREN) of >40, providing pitting and crevice corrosion resistance superior to austenitic and duplex stainless steels in almost all corrosive media, and a Critical Pitting Temperature exceeding 50°C nb. versions of the PREN formula also include W as a positive influence on overall pitting resistance.
Chemical Properties:
| Cr | Ni | Mo | Co | Nb (+Ta) | Ti | V | W | Cu | C | Mn | N | Si | P | S | Fe | Al | |
| Min | 24.00 | 6.00 | 3.00 | 0.50 | 0.50 | 0.20 | 0.10 | ||||||||||
| Max | 26.00 | 8.00 | 4.00 | 1.00 | 1.00 | 1.00 | 0.30 | 0.80 | 0.025 | 0.005 | Bal |
Mechanical Properties:
| 0.2% Proof Stress | 550 N/mm2 | 79.8 ksi |
| Tensile Strength | 750 N/mm2 | 108.8 ksi |
| Elongation, 5.65√S0 | 25% | |
| Reduction of area | 45% | |
| Hardness (Brinell) | 270 max. | |
| Impact Strength (Room Temp) | 80J | 59 lb.ft |
| Impact Strength (-46oC) | 60J av (45J min) | 44 lb.ft av (33 lb.ft min) |
Notes:
- Testing shall be carried out in accordance with ASTM A370 or EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness)
- Minimum properties quoted (tested at room temperature in a longitudinal direction)
- Testing performed on each melt of material per heat treatment batch
- Hardness shall be in accordance with NACE MR 1075 with a maximum HRC of 2
- ASTM G48A corrosion test (at 50°C) no pitting and < 3.0 g/m2 weight loss (ASTM specification < 4.0 g/m2)
- Ferrite content 35-55%
- Microstructure certified free from grain boundary carbides, sigma, chi and laves phases
Physical Properties:
| Density (Kg/m3) | 7810 |
| Magnetic Permeability (20°C) | 33 |
| Young’s Modulus (kN/mm2) | 199 |
| Specific Electrical Resistance, 20°C (µΩ.m) | 0.8 |
| Mean coefficient of thermal expansion, 20-300°C (m/m/oC) | 11.1 x 10-6 |
| Specific Heat, 20°C (J/kg.K) | 475 |
| Thermal conductivity, 20°C (W/m.K) | 14.2 |
| Fracture Toughness, kQ (MPa/m2) | 98 |