The austenitic stainless steels possess a unique combination of properties which makes them useful at cryogenic (very low) temperatures, such as are encountered in plants handling liquefied gases. These steels at cryogenic temperatures have tensile strengths substantially higher than at ambient temperatures while their toughness is only slightly degraded
Impact Strength

Typical impact strengths are as shown in Figure 1. Considerable austenitic stainless steel has therefore been used for handling liquefied natural gas at a temperature of -161°C, and also in plants for production of liquefied gases. Liquid oxygen has a boiling temperature of -183°C and that of liquid nitrogen is -196°C.

Figure 1. Impact Strength versus Temperature
Ductile to Brittle Transition

The ferritic, martensitic and precipitation hardening steels are not recommended for use at sub-zero temperatures as they exhibit a significant drop in toughness, even at only moderately low temperatures, in some cases not much below room temperature. The duplex stainless steels have better low temperature ductility than the ferritic and martensitic grades; they are generally quite useable down to at least -50°C, which therefore usually places a lower temperature limit on their usefulness. The "ductile to brittle transition" from which these grades suffer is also a common feature of carbon and low alloy steels, some of which have Ductile to Brittle Transition Temperatures (DBTT) close to 0°C.