17-4 PH stainless steel round bar isa martensitic precipitation-hardening alloy known for its exceptional combination of high strength, hardness, and corrosion resistance. The "PH" signifies its ability to be hardened through a single, low-temperature heat treatment process, which minimizes warping and scaling. Its chemical composition includes chromium, nickel, and copper.This versatile material is widely used in demanding industries like aerospace, chemical processing, and oil and gas due to its excellent mechanical properties and resistance to corrosive media. It is also known as UNS S17400 or AISI 630. The specific heat treatment can be tailored to optimize different mechanical properties.The most well known precipitation hardening steel is 17-4 PH. The name comes from the additions 17% Chromium and 4% Nickel. It also contains 4% Copper and 0.3% Niobium. 17-4 PH is also known asstainless steel grade 630.