Inconel 690 · UNS N06690 · W. Nr. 2.4642
Inconel 690 (N06690): composition, properties, fittings and flanges
Inconel 690 (N06690, W. Nr. 2.4642) is High-chromium nickel-based alloy for stress corrosion cracking resistance. Inconel 690 is specified at Nickel 58.0 min, Chromium 27.0 - 31.0, Copper 0.50 max. Inconel 690 raises chromium to about 30 % specifically to resist primary-water stress corrosion cracking, which is why it replaced…
- UNS
- N06690
- W. Nr.
- 2.4642
- Density
- 8.19 g/cm³ (0.296 lb/in³)
- Key strength
- 586 MPa / 85 ksi
Identification and standards
| Short form | Inconel 690 · UNS N06690 · W. Nr. 2.4642 |
|---|---|
| Classification | High-chromium nickel-based alloy for stress corrosion cracking resistance |
| UNS | N06690 |
| Werkstoff number | 2.4642 |
| Material family | Inconel Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Nickel (Ni) | 58.0 min | Matrix and SCC resistance |
| Chromium (Cr) | 27.0 - 31.0 | Oxidation and SCC resistance |
| Iron (Fe) | 7.0 - 11.0 | Matrix |
| Carbon (C) | 0.05 max | - |
| Manganese (Mn) | 0.50 max | - |
| Silicon (Si) | 0.50 max | - |
| Copper (Cu) | 0.50 max | - |
| Sulphur (S) | 0.015 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 586 MPa / 85 ksi |
|---|---|
| 0.2 % yield strength, min | 241 MPa / 35 ksi |
| Elongation in 2 in, min | 30 % |
| Typical hardness, annealed | 150 - 200 HB |
| Relative SCC resistance vs Inconel 600 | Several times higher in primary water |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.19 g/cm³ (0.296 lb/in³) |
|---|---|
| Melting range | 1343 - 1377 °C (2450 - 2510 °F) |
| Modulus of elasticity | 211 GPa (30.6 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 12.0 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 13.5 µm/m·°C |
| Specific heat capacity | 450 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM B564 / ASME SB-564 (UNS N06690) |
|---|---|
| Butt weld fittings | ASTM B366 / ASME SB-366 (WP690) |
| Seamless pipe & tube | ASTM B167 / B163 / ASME SB-167 |
| Plate / sheet / strip | ASTM B168 / ASME SB-168 |
| Bar / rod | ASTM B166 / ASME SB-166 |
| Welding consumables | ERNiCrFe-7 or ERNiCr-3 |
| UNS / EN / China | UNS N06690 · W. Nr. 2.4642 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Nuclear steam generator tubing, tube sheets and divider plates
- Caustic evaporator piping and vessels
- Nitric acid and nuclear fuel reprocessing equipment
- Waste incineration and flue gas treatment components
Welding, forming and machining
- Welding
- Weld with ERNiCrFe-7 filler for nuclear work or ERNiCr-3 for general service. Control interpass temperature and avoid contamination to preserve SCC resistance.
- Heat treatment
- Solution anneal at 1040 - 1100 °C and water quench, or stress relieve at 870 - 930 °C depending on specification.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Inconel 690 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.