Precipitation Hardening (PH) Stainless Steel
PH alloys are similar to other stainless steel and nickel-based alloys, with one major exception: They contain small additions of copper, aluminum, phosphorus, or titanium. After a part made of a PH alloy has been formed, it is given an age-hardening treatment in which these elements precipitate as hard intermetallic compounds that significantly increase hardness and strength.