Stainless steel is a corrosion-resistant steel with a chromium content of not less than 12%, which is short for stainless and acid-resistant steel. Chromium in steel reacts with oxygen in corrosive medium to form a thin oxide film on the surface of steel, called self-passivation film, which makes steel corrosion resistant in air, water, acid, alkali and salt. In addition to chromium, alloy elements such as nickel, molybdenum, copper and titanium can also be added to the steel to make it have better corrosion resistance, processability or mechanical properties. Stainless steel is generally divided into chromium stainless steel, chromium nickel stainless steel and high-strength stainless steel.

The chromium content of chromium stainless steel is between 12 and 30%. It was first made by H. Brierley of England in 1912. According to the structure at room temperature, chromium stainless steel can be divided into ferrite stainless steel and martensitic stainless steel. Ferritic stainless steel has low carbon content, can not be strengthened by heat treatment, low strength and poor weldability, such as 0Cr13, 0Cr17Ni, etc. It is mainly used to make equipment in nitric acid industry, man-made fiber and food industry. Ultra-pure ferritic stainless steel with total carbon and nitrogen content less than 0.02%, such as 00Cr27Mo steel, has better corrosion resistance and process performance. Martensitic stainless steel has a high carbon content and can obtain high strength and hardness after quenching and heat treatment, but its corrosion resistance is poor, such as 1Cr13, 4Cr13, 9Cr18MoV steel, etc., which is mostly used to manufacture steam turbine blades, bolts that bear high loads, and valve discs, cutters and bearings that require high hardness.

Chromium-nickel stainless steel contains 12~30% chromium, 6~12% nickel and a small amount of other elements. The carbon content of this steel is very low, and it presents austenite or austenite plus ferrite structure at room temperature. It has better corrosion resistance, weldability and formability than chrome stainless steel. The earliest chrome-nickel stainless steel was made by B. Strauss and E. Morel of Germany in 1912. The most commonly used modern 18-8 stainless steel contains 18% chromium and 8% nickel. This stainless steel has low yield strength and cannot be strengthened by heat treatment. However, the tendency of processing strengthening is large. High strength wire and strip can be obtained through cold processing. Common steel grades such as 0Cr * * * i9, 0Cr17Ni13Mo2, etc., are mostly used to make chemical containers, equipment linings, transmission pipes, medical devices and instruments, etc. Stainless steel with copper and molybdenum, such as 0Cr * * i18Mo2Cu2Ti, has good corrosion resistance in non-oxidizing media such as dilute sulfuric acid and phosphoric acid. Ultra-low carbon nickel-chromium austenitic stainless steel with carbon content below 0.03%, such as 00Cr * * i10, 00Cr17Ni13Mo2, and chromium-nickel austenitic stainless steel with titanium, such as 0Cr * * i9Ti, have good resistance to intergranular corrosion. Chromium-nickel austenitic stainless steels containing manganese and nitrogen, such as 1Cr18Mn8Ni5N and 0Cr * * * i9N, have high yield strength.

High strength stainless steel is divided into martensitic stainless steel and precipitation strengthened stainless steel. Martensitic stainless steel belongs to chromium stainless steel. Precipitation-strengthened stainless steel is a chromium-nickel stainless steel containing an appropriate amount of copper, aluminum, titanium and other alloy elements. After solution heat treatment, it presents austenite, semi-austenite or martensite structure. After aging heat treatment, the steel further precipitates dispersed strengthening phase, which makes the steel have high strength () ≥ 1000 MPa), and maintain good toughness and corrosion resistance, such as 0Cr17Ni26A12MoVTi, 0Cr17Ni7Al and 0Cr17Ni4Cu4Nb steel, etc., which are commonly used to make corrosion-resistant high-pressure vessels, high-load parts, aircraft skins and springs. In addition, phase transformation induced plasticity stainless steel (TRIP) is a newly developed stainless steel with higher strength and better corrosion resistance.

Stainless steel bearings can organize mass production and achieve high strength and precision. It can be widely used in various products that are easy to rust and strong corrosion.

AISI SUS440C stainless steel (domestic No.: 9Cr18Mo, 9Cr18) is used as the bearing ring and rolling body material, which is subject to vacuum quenching and tempering treatment. AISI 304 stainless steel (domestic No.: 1Cr18) is used as the cage and sealing ring skeleton material. Compared with ordinary bearing steel, stainless steel bearing has stronger rust prevention and corrosion resistance. Select appropriate lubricant, dust cover, etc., which can be used in the environment of - 60 ℃~300 ℃. Stainless steel bearings are widely used in food processing, medical devices, and pharmaceutical machinery due to their high mechanical strength and large load capacity.

Main uses: medical instruments, low-temperature engineering, optical instruments, high-speed machine tools, high-speed motors, printing machinery, food processing machinery.