Inconel Alloys
Inconel 690 (UNS N06690) — Composition, Properties & Supply
Inconel 690 (UNS N06690) raises chromium to 27–31% and is the replacement material for PWR nuclear steam generator tubing, offering far better intergranular corrosion and stress-corrosion-cracking resistance than Inconel 600 or the 800 series.
What is the chemical composition of Inconel 690?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Ni | Ni | ≥ 58.0 |
| Cr | Cr | 27.0–31.0 |
| Fe | Fe | 7.0–11.0 |
| C | C | ≤ 0.05 |
| Mn | Mn | ≤ 0.50 |
| Si | Si | ≤ 0.50 |
| Cu | Cu | ≤ 0.50 |
| S | S | ≤ 0.015 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of Inconel 690?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 586 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 240 MPa | Room temperature |
| Elongation | ≥ 30 % | Gauge length 50 mm / 4D |
| Hardness | ≤ 190 HB | Brinell / Rockwell |
What are the physical properties of Inconel 690?
| Property | Value |
|---|---|
| Density | 8.19 g/cm³ |
| Melting range | 1343–1377 °C |
| Thermal conductivity | 11.1 W/m·K |
| Elastic modulus | 211 GPa |
| Maximum service temperature | 1000 °C |
What are the key characteristics of Inconel 690?
- High chromium gives outstanding SCC resistance
- Better intergranular corrosion resistance than 600 and 800 series
- Long-term stability in chlorides and high-temperature water
- Good weldability with ERNiCrFe-7 class fillers
Where is Inconel 690 used?
- PWR steam generator tubing
- Nuclear evaporators and tube supports
- Nitric acid production equipment
- Waste incinerator superheater tubes
- High-temperature chloride-bearing chemical plant
Which standards and specifications cover Inconel 690?
What product forms are available?
Frequently asked questions
Why did nuclear steam generator tubing move from Inconel 600 to 690?
600 suffered primary- and secondary-side stress-corrosion cracking in high-temperature, high-pressure borated water. 690 raises chromium to about 30%, sharply reducing grain-boundary chromium depletion and improving SCC resistance by more than an order of magnitude, which is why it became the standard for PWR SG tubing.
Need Inconel 690 bar, tube, plate or forgings?
Send the grade, dimensions, standard and quantity. We answer within 10 minutes on working days and quote within 24 hours, with EN 10204 3.1 certification.
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