The most common reason we see is for elevated temperature use and the best grade for this is Inconel 718 to AMS5962. Inconel 718 requires an ageing treatment to release its full mechanical properties which can be costly, but this then enables it to be used between -200C to +550C where it will outperform Inconel X750 and Nimonic 90.
One slightly more cost effective option is to use Inconel X750 which can be bought in 2 different conditions No1 Temper (AMS5698) and Spring Temper (AMS5699) which each has its own merits. One thing to watch out for with this material is the heat treatment as this will not only determine the Tensile strength (which can be as low as 900 Mpa (130 KSI) or as high as 1750Mpa (254 KSI)) but it will also determine the maximum operating temperature which can be limited to +370C or increased to +550C depending on the thermal treatment.
Another use for Inconel X750 is its corrosion resistance in a sour gas environment. Material intended for this use can be certified to NACE requirements.
The surface integrity of any Nickel Alloy spring subjected to such hostile environments is super critical, to support this all of the springs we produce are mandrel coiled.
If you have any queries about Inconel Springs, their uses or if you have questions regarding the different grades not mentioned here please dont hesitate to contact us.