Alloy 718 is a precipitation hardened nickel-chromium alloy with additions of niobium, molybdenum, aluminium and titanium for improved corrosion resistance combined with extremely high strength and excellent weldability, including resistance to cracking after welding.Unlike many other superalloys, it’s also quite easy to weld. This combination of great high-temperature performance up to 700°C and ease of weld fabrication have made alloy 718 one of the most, if not the most popular superalloy used in industry. It can be wrought (most often), cast (rarely) or powder injection molded.Alloy 718 was initially developed for the aerospace industry but its excellent strength and corrosion resistance were recognised by the oil industry and it is now widely used in this field as well.
Applications of Alloy 718
Characteristics ALLOY 718 | 2.4668
Chemical composition – limits in %
| Chemical elements | AMS5662/5663 | API 6A |
| Ni | 50,00 – 55,00 | 50,00 – 55,00 |
| Cr | 17,00 – 21,00 | 17,00 – 21,00 |
| Nb | 4,75 – 5,50 | 4,87 – 5,20 |
| Mo | 2,80 – 3,30 | 2,80 – 3,30 |
| Co | max. 1,00 | max. 1,00 |
| Ti | 0,65 – 1,15 | 0,80 – 1,15 |
| Al | 0,20 – 0,80 | 0,40 – 0,60 |
| Mn | max. 0,35 | max. 0,35 |
| Cu | max. 0,30 | max. 0,23 |
| C | max. 0,08 | max. 0,045 |
| P | max. 0,015 | max. 0,010 |
| S | max. 0,015 | max. 0,010 |
| Pb | max. 0,0005 | max. 0,001 |
| Se | max. 0,0003 | max. 0,0005 |
| Bi | max. 0,00003 | max. 0,00005 |
| Fe | Rest | Rest |
| Specification | AMS 5663 | AMS 5596 | API 6A |
|---|---|---|---|
| Yield strength | min. 1034 MPa | min. 1034 MPa | min. 827 MPa |
| Tensile strength | min. 1275 MPa | min. 1240 MPa | min. 1034 MPa |
| Elongation | min. 12% | min. 12% | min. 20% |
| Hardness | 32-40 HRC* |
*NACE MR0175 requires hardness 40 HRC max. only
Partial part type display:
