The interplay between chromium and carbon is further explained in the two graphs of the iron-chromium phase diagram. The iron-chromium phase diagram at (a) shows 12% chromium and (b) shows 17% chromium. Higher chromium alloys, the range over which full austenitization can occur is further restricted.
The variety of martensitic stainless steels would be very limited if only chromium and carbon were available as alloying elements, but fortunately nickel can make an important contribution. Nickel greatly expands the chromium levels and temperatures at which austenite is stable,
Volume 4D, Heat Treating of Irons and Steels ⇒ Heat Treated High-Alloy Steels ⇒ Heat Treating of Martensitic Stainless Steels ⇒ Alloying
