ATI C-200TM, ATI C-250TM, and ATI C-350TM alloys (18% nickel maraging steels) are divided into two broad classes depending on the primary strengthening element in the chemical analysis. The original maraging steels, introduced in the early 1960s, depend on cobalt (7-12% cobalt depending on grade) as their strengthening agent; they are cobalt strengthened 18% nickel maraging steels. In the early 1980s, ATI introduced a new type of maraging steel which
contains no cobalt and has titanium as a primary strengthening agent; they are titanium-strengthened 18% nickel maraging steels.
Cobalt-strengthened grades, or “C-type 18 Ni maraging”, are designated by the letter “C” in the grade identification (example: ATI C-250). Titanium-strengthened grades, or “T-type 18Ni maraging”, are designated by the letter “T” in the grade identification (example: ATI T-250).
This data sheet covers the C-type 18Ni maraging steels manufactured by ATI: ATI C-200, ATI C-250, ATI C-300, and ATI C-350. Information on the T-type grades is available in a separate Technical Data Sheet. ATI continues to be a leading producer of the titanium-strengthened alloys. It should be emphasized that the essential difference between C-type and T-type maraging steels is the chemical analysis. In terms of mechanical properties and recommended
processing, there are few, if any, significant differences. Since high purity melting is essential to assure optimum mechanical properties, ATI employs double vacuum melting – under strictest quality control – for all maraging steel grades