Precipitation hardening stainless steel refers to adding different types and quantities of strengthening elements on the basis of the chemical composition of stainless steel, and precipitating different types and quantities of carbides, nitrides, carbonitrides and intermetallic compounds through the precipitation hardening process. , a type of high-strength stainless steel that not only improves the strength of steel but maintains sufficient toughness, referred to as PH steel. Precipitation hardening stainless steel can be divided into three categories: martensitic, semi-austenitic and austenitic according to the metallographic structure of its matrix.
The Classification of Precipitation Hardening Stainless Steel
According to the content of the main alloying elements and the added hardening elements in the steel, it is divided into four categories, namely:
(1) Martensitic precipitation hardening stainless steel has a carbon content generally lower than 0.1%. Strengthening is done by adding hardening elements (copper, aluminum, titanium, aluminum, etc.) to make up for the lack of strength. The chromium content is generally higher than 17%, and an appropriate amount of nickel is added to improve corrosion resistance;
(2) Maraging stainless steel, containing no more than 0.03% carbon to ensure the toughness, corrosion resistance, weldability and processability of the martensite matrix, and containing no less than 12% chromium to ensure corrosion resistance. In addition, the alloying element cobalt is added to further improve the heat treatment effect of steel;
Semi-austenitic, i.e. transitional precipitation hardened stainless steel, containing not less than 12% chromium. This type of steel has low carbon content and uses aluminum as its main precipitation hardening element. This type of steel has better overall properties than martensitic precipitation hardening stainless steel;
Austenitic precipitation hardening stainless steel is a stainless steel with a stable austenitic structure in both the quenching state and the aging state. It contains high nickel (higher than 25%) and manganese, and a chromium content higher than 13% to ensure good quality. For corrosion resistance and oxidation resistance, titanium, aluminum, vanadium or phosphorus are usually added as precipitation hardening elements, while trace amounts of boron, vanadium, nitrogen and other elements are added to obtain excellent comprehensive properties.
The Features of Precipitation Hardening Stainless Steel
Precipitation hardening stainless steel has comprehensive properties such as high strength, high toughness, high corrosion resistance, high oxidation resistance, and excellent formability and weldability.
The Applications of Precipitation Hardening Stainless Steel
Because precipitation hardening stainless steel has good formability and good weldability, it can be used as an ultra-high-strength material in the nuclear industry, aviation and aerospace industry.
