17-7PH is an austenitic-martensitic precipitation-hardening stainless steel developed from 18-8 CrNi, also known as controlled phase transformation stainless steel.

17-7PH stainless steel, after solution heat treatment, forms an unstable austenitic structure with excellent ductility and machinability. Adjustments cause the composition to change during the precipitation of carbides in the austenite, followed by martensitic transformation treatment. Most of the structure then becomes ductile低碳tempered martensite, which is the steel's service state, exhibiting good medium-temperature mechanical properties. The corrosion resistance of 17-7PH is superior to that of typical martensitic stainless steels.

17-7PH Chemical Composition:Carbon C: ≤0.09 Manganese Mn: ≤1.00 Silicon Si: ≤1.00 Chromium Cr: 16.0~18.0 Nickel Ni②: 6.5~7.75 Phosphorus P: ≤0.04 Sulfur S: ≤0.03 Aluminum Al: 0.75~1.5