17-4PH is a chromium-nickel-copper precipitation hardening martensitic stainless steel. This grade of stainless steel is characterized by high strength, hardness and corrosion resistance. The mechanical properties are improved by heat Treatment and compressive strengths of up to 1100-1300 MPa (160-190 ksi) can be achieved. This grade cannot be used at temperatures above 300°C (572°F) or at very low temperatures. It has good corrosion resistance to atmospheric and dilute acids or salts, and its corrosion resistance is comparable to that of 304.

17-7PH is austenitic-martensitic precipitation hardening stainless steel developed on the basis of 18-8CrNi, also known as controlled phase change stainless steel. 17-7PH stainless steel is unstable austenitic organization after solid solution Treatment, with good plastic toughness and machinability, after tempering, so that the austenite precipitation of carbides after the change in composition, and then through the martensitic transformation process, most of the organization is transformed into a low carbon tempering process with good toughness. After tempering, the austenite precipitation carbide composition changes, and then through the martensitic transformation process, most of the organization is transformed into a low carbon tempered martensite with good toughness, and has good mechanical properties at medium temperature. 17-7PH corrosion resistance is better than the general martensitic stainless steel.