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718 NACE / NACE MRO175
NACE 718 is a precipitation hardened nickel-chromium alloy. It combines high strength in the aged condition with good corrosion resistance and weldability. NACE 718 indicates material stocked in the heat treated condition and provides high strength while meeting the maximum hardness requirements of the NACE MR0175, MR0103 and ISO 15156-3 specifications for use in oil tools used for sour service.
NACE 718 is annealed between 1875-1925°F and water quenched. Subsequently it is aged in the range of 1425-1475°F for 6-8 hours and air cooled or faster to room temperature.
Chemistry
| Ni | Cr | Mo | Mn | Cu | Si | C | S | P | Co | Cb+Ta | Pb | Se | Bi | Mg | Ti | Al | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MIN | 50 | 17 | 2.8 | - | - | - | - | - | - | - | 4.87 | - | - | - | - | 0.8 | 0.4 | - |
| MAX | 55 | 21 | 3.3 | 0.35 | 0.23 | 0.35 | 0.045 | 0.01 | 0.01 | 1.0 | 5.2 | 1000 ppm |
0.0005 ppm |
50 ppm |
0.0006 ppm |
1.15 | 0.6 | Balance |
Specifications
API 6A, API 6A718
ASME SB 637
ASTM B 670
EN 2.4668
ISO 15156-3
NACE MR0103, NACE MR0175
UNS N07718
Werkstoff 2.4668
Inventory
718 NACE Plate, 718 NACE Round Bar, 718 NACE Sheet, 718 NACE Welding Products
Common Trade Names
Inconel® 718, Nickel Alloy 718
Features
- Highly resistant to chloride and sulfide stress corrosion cracking
- High strength
- Good corrosion resistance
Applications
- Valves
- Wellhead completion equipment
- Fasteners
- Blowout preventers (BOPs)
- Tubing hangers
- Mandrels
Physical Properties
Density: 0.297 lb/inch3
Melting Point: 2160 - 2440°F
| Temperature, °F | 70 | 200 | 400 | 600 | 1000 | 1200 |
| Coefficient* of Thermal Expansion, in/in°F x 10-6 | - | 7.3 | 7.5 | 7.7 | 8.1 | 8.4 |
| Thermal Conductivity Btu • ft/ft2 • hr • °F |
6.4 | 7.2 | 8.2 | 9.3 | 11.3 | 12.3 |
| Modulus of Elasticity, Dynamic psi x 106 | 29.0 | 28.4 | 27.6 | 26.7 | 24.8 | 23.7 |
* 70°F to indicated temperature.
Mechanical Properties
Minimum Specified Properties, API 6A 718 bar Solution Annealed And Aged Condition
| Minimum | Maximum | |
| Ultimate tensile strength, ksi | 150 | - |
| 0.2% yield strength, ksi | 125 | 145 |
| Elongation, % | 20% | - |
| Reduction of area, % | 35% | - |
| Impact Strength*Min average/ min single, ft-lbs |
40/35 | - |
| Hardness, Rockwell C | 32 | 40 |