Semi-austenite precipitation hardening stainless steel is a kind of high-alloy ultra-high strength steel, such as common 17-7PH, PH15-7Mo and AFC-77. This type of high-strength steel undergoes solid solution treatment and is cooled to room temperature to form austenite. After cold working, cold treatment or heating to 750°C for adjustment treatment, the austenite is transformed into martensite. Finally, aging at 400-550°C, an ultra-high-strength steel in which the second phase strengthened structure is dispersed and distributed on the tempered martensite matrix is obtained. When this kind of steel is used for a long time above 315℃, the material will become brittle due to the precipitation of intermetallic compounds, so the use temperature should be limited to below 315℃. This type of high-strength steel is mainly used to manufacture components of aerospace devices, high-pressure vessels and high-stress corrosion chemical equipment parts.
