Cryogenic Stainless Steel: Exploring Grades for Critical, Low Temperature Applications
If you need a component that can resist corrosion in extremely frigid environments, it’s time to consider high-performance steel. In this post, we’ll examine how low temperatures affect steel properties and characteristics—and discuss the right bearing-quality, cryogenic stainless steel for your critical application.
How Low Temps Affect Steel Performance
Cryogenic service means different things to different people. For our purposes, we’ll consider cryogenic applications to be at temperatures in the range of -40°F to −240°F (-40oC to -151oC), a range often covered by industries like food processing and rocket engine component manufacturing.
Many steels with acceptable characteristics at “room-temperature” perform poorly at cryogenic temperatures. In the cold, atoms in a metal rearrange as the crystalline structure loses thermal energy, altering the material properties.
It’s easy to imagine that under very cold temperatures, metal gets brittle. Yet other characteristics change too, including:
- Corrosion resistance
Even at frigid temperatures, bearings have to roll under load, and valves still have to seal and flow at high speeds—and that’s when high-performance cryogenic steels are an excellent choice.
There are some very good, non-stainless, low-temperature grades of steel available. If that’s what your application calls for, it’s possible that 52100 as a VAR or VIM-VAR will work, because it has a fine microstructure. However, CREN (Corrosion Resistant - Nitrogen) steels or other cryogenic stainless steels are best for critical applications, as cold environments generally accelerate corrosion.
It’s interesting to note that sub-zero temperatures may increase yield and tensile strength (bonus!), but in most applications, the losses in ductility and toughness outweigh the strength increase. The cold also causes dimensional changes and alters magnetic properties. Depending on the use case, a shift in magnetics may be harmful or beneficial. For example, metal can become superconductive at cryogenic temperatures.
XD15NW: Properties of a High-Performance Cryogenic Steel
An excellent high-performance stainless steel for cryogenic conditions is XD15NW. A specialty steel from Aubert & Duval, it demonstrates remarkable corrosion resistance with a very high level of hardness.
An inherently fine microstructure is one of the keys to XD15NW’s low-temperature performance. As temperatures plummet, its structure endures, making it ideal for high-stress applications where hardness, fatigue resistance, and corrosion resistance are paramount.
Parts made of XD15NW, such as bearings, are stable at sub-zero temperatures. The microstructure experiences less thermal effects, keeping its dimensions better than other steels. The fine microstructure also makes for surfaces that polish to a tight seal.
XD15NW is a logical choice for any spec that requires a stainless steel that cannot fail.
Sullivan Has Steel for Any Operating Temperature
Sometimes, our customers require high-performance, bearing-quality, cryogenic stainless steels for their critical applications. They are often from sectors such as:
- Aerospace & Rocket Engineering
- Aircraft Manufacturing
- Food Processing
- Hydrogen & CO2 Handling
- Semiconductor Manufacturing
If you’re looking for a grade that’ll excel in cryogenic conditions or low-temperature applications, talk to one of our experts today.