Nickel alloys for nuclear power
In primary and secondary circuits the material problem is rarely strength at temperature. It is stress-corrosion cracking in high-purity water, and staying stable for a design life measured in decades.
All 7 grades on this page are melted, forged and tested at our own plant in Shanghai and released with EN 10204 3.1 or 3.2 documentation. Chemistry, mechanical results and the heat number travel with the material.
Three mechanisms that decide the grade
Not a materials handbook — just the three things that most often change the answer on a real enquiry.
Why 690 replaced 600 in new steam generators
Inconel 600 served for decades and then produced stress-corrosion cracking on the primary side of steam generator tubing. Inconel 690 raised the chromium content to roughly 30 % and became the replacement for new construction. Both are still quoted, because the installed base runs on the older grade.
Springs and fasteners are a separate problem
Inconel X-750 carries the spring, bolt and guide-tube duty where relaxation resistance at temperature matters more than corrosion resistance. It is age-hardenable, so the ageing treatment and the test direction belong on the order.
Quality programme, not just alloy
Nuclear orders usually add a quality programme on top of the material standard. That changes documentation, witness points and sometimes what we can offer at all, so it has to be known before the heat is scheduled rather than after.
7 grades we melt for Nuclear power
Each one links to its specification page, with chemistry, standards by product form and the EN 10204 documents we issue. Showing 7 of 7.
Inconel 690
Excellent resistance to oxidation and sulfidation at high temperatures, ideal for use in extreme heat environments.
Inconel 600
Withstands temperatures up to 2000°F (1093°C) without losing mechanical properties.
Inconel X-750
INCONEL X-750 maintains its strength and stability in high-temperature environments, withstanding up to 704°C, which makes it ideal…
Inconel 718
INCONEL 718 has excellent mechanical properties, including high tensile, creep, and rupture strength, maintained up to 700°C.
Inconel 617
Excellent resistance to oxidation and carburization at temperatures up to 1100°C.
XM-19
PREN (Pitting Resistance Equivalent Number) ≥ 42, far exceeding 316L/2205, with excellent resistance to pitting, crevice corrosion…
Nimonic 95
Exceptional resistance to creep deformation and rupture up to about 980 °C, for long-term load-bearing parts.
Three things to put on the enquiry
- Tell us at enquiry stage if a nuclear quality programme applies. — It changes the documentation package and the inspection plan. Discovering it after the material is cut is expensive for everybody.
- Distinguish replacement from new build. — The installed base on Inconel 600 needs 600. New construction is usually specified in 690. Quoting the modern grade into a 600 scope is a common and avoidable mix-up.
- Test direction and location belong on the order. — Longitudinal or transverse, and whether test pieces come from the ends or mid-length, is not a detail for this class of work.
Nuclear power: questions buyers ask
The answers below are drawn from the same grade data as the tables above.
Which grades do you supply for nuclear duty?
Inconel 600, 690, 617, 718 and X-750, Nimonic 95 and XM-19. Seamless tube for steam generator and heat exchanger service, bar and forgings for internals, springs and fasteners.
Is the material supplied to a nuclear quality programme?
Not by default. We supply to the ASTM or EN product standard you name with EN 10204 3.1 or 3.2 documentation. If a nuclear quality programme applies to your order, tell us at enquiry stage so the documentation and inspection plan can be agreed before the heat is scheduled.
Can 690 be supplied as seamless tube?
Yes. Seamless tube is the form 690 is most often bought in for steam generator and heat exchanger work, and it is quoted against the tube standard named on your specification.
Send the grade, the size, the quantity.
We will quote against your specification, including lead time, inspection level and documents.