Alloy 825

Alloy 825 can perhaps be seen as the entry point when moving from stainless steels to more expensive Nickel alloys. With >40% Ni and >20%Cr content, then it is certainly a step-up in price compared with super duplex alloys.

So, why would you specify it ?

Nickel-Iron-Chromium alloys such as Alloy 825, also known as Incoloy 825 (Special Metals Corporation’s family of Nickel-Iron-Chrome alloys is known as Incoloy^® ) were developed to provide a more cost-effective solution for applications requiring high-temperature and corrosion resistance – achieved by lowering the nickel content (compared with even more exotic alloys).

Duplex and super duplex stainless steels provide considerable ‘bangs for your buck’ in terms of both corrosion resistance and strength. However, there are practical limitations to the operating temperature range, which is where Alloy 825 comes into play. Whilst standard super duplex alloys achieve a Yield Strength >80ksi, it is only >36ksi for Alloy 825. Similarly, the PREN (pitting resistance equivalent number) is only 31, whereas a super duplex alloy achieves >40.

However:
a) Alloy 825 can be used in operating temperatures of up to 540degC, whereas super duplex stainless steels are limited to 250degC.
b) Alloy 825 retains much of its impact strength at cryogenic properties, whereas duplex and super duplex stainless steel properties tend to drop-off at very low temperatures.

The high nickel content of Alloy 825 ensures resistance to stress corrosion cracking. Additions of molybdenum and copper allow it to resist reducing environments such as sulphuric and phosphoric acids. A controlled addition of titanium inhibits the intergranular corrosion that might otherwise occur at elevated temperatures.

As our range of stock has expanded we have already seen an uplift in orders. Alloy 825 is being commonly used by our customers in components for valves and pumps for the chemical process industries and down-hole equipment for corrosive service. We are stocking a comprehensive range of solid bar sizes from 3/4″ up to 10″ diameter.

Get in touch with Langley Alloys to find out more about Alloy 825.