ATI 200 alloy (UNS Designation N02200) and ATI 201 alloy (UNS Designation N02201) are wrought commercially pure nickel. The alloys differ only in the maximum carbon level allowed by specification, 0.15 percent maximum for ATI 200 alloy and 0.02 percent maximum for ATI 201 alloy. Either alloy provides highly ductile mechanical properties across a wide temperature range. Either alloy provides corrosion resistance in neutral to moderately reducing environments. In the annealed condition, either alloy possesses the approximate strength of mild steel. As-rolled material is sometimes furnished to provide higher strength levels.

The nickel alloys are readily fabricated by standard fabrication practices. The materials are covered by a variety of specifications and are assigned maximum allowable stresses in the ASME Boiler and Pressure Vessel Code.

The ATI 200 and ATI 201 alloys provide high thermal and electrical conductivity in comparison to nickel base alloys, stainless and low alloy steels. The ATI 200 and ATI 201 alloys are ferromagnetic.

Because long-time exposures of ATI 200 alloy in the 800 to 1200°F (427 to 649°C) range result in precipitation of a carbon containing phase and loss of ductility, the ATI 200 alloy is not recommended for service above 600°F (316°C). In applications above 600°F (316°C), however, the low carbon ATI 201 alloy may be considered. As proposed service temperatures approach 800°F, (427°C), resistance to creep should be considered a design criterion.