A common feature of Outokumpu high temperature steels is that they are designed primarily for use at temperatures exceeding ~550°C, i.e. in the temperature range where creep strength as a rule is the dimensioning factor and where HT corrosion occurs. Optimising steels for high temperatures has meant that their resistance to aqueous corrosion has been limited. All steels are austenitic, resulting in relatively high creep strength values.

All steels except EN 1.4948 (i.e., all EN 1.48XX) are included in the European Standard EN 10095 "Heat-resisting steels and nickel alloys". EN 1.4948 is included in EN 10028-7 "Flat products made of steels for pressure purposes - Part 7: Stainless steel". All the above steel grades are also included in ASTM A240.

353 MA® is an alloy with a significantly higher nickel content than the other steels. Like 153 MA™ and 253 MA® it has increased contents of silicon and nitrogen, and is microalloyed with rare earth metals (REM). The maximum service temperature in air is 1150°C, but after service at temperatures below ~950°C there is a risk for reduced room temperature impact toughness.