Stainless steel material

Stainless steel material is a kind of material, with close to mirror brightness, hard and cold touch, belongs to the more avant-garde decorative materials, with excellent corrosion resistance, formability, compatibility and toughness and other series characteristics, used in heavy industry, light industry, daily goods industry and building decoration industry.

Stainless steel is referred to as stainless steel, it is composed of stainless steel and acid steel two parts, in short, can resist atmospheric corrosion of steel called stainless steel, and can resist the corrosion of chemical media steel called acid steel. Generally speaking, chromium content Cr more than 12% steel has the characteristics of stainless steel according to the microstructure of stainless steel after heat treatment can be divided into five categories: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic - ferritic biphase stainless steel and precipitation hardened stainless steel.

Because stainless steel has excellent corrosion resistance, formability, compatibility and strength and toughness in a wide range of temperature, it has been widely used in heavy industry, light industry, household goods industry and building decoration and other industries.

Classification method

There are many classification methods for stainless steel, the common ones are as follows, among which the classification according to metallographic structure is the most common.

Classification of chemical composition

Basically can be divided into chromium stainless steel (such as ferritic series, Martensitic system column) and chromium nickel stainless steel (such as Austenitic system column, abnormal series, precipitation hardening series) two systems.

Metallographic classification

Can be divided into austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel, precipitation hardening stainless steel.

Classified according to corrosion resistance type

It can be divided into stress corrosion-resistant stainless steel, pitting corrosion-resistant stainless steel, intergranular corrosion resistant stainless steel, etc.

Classification by functional characteristics

Can be divided into easy cutting stainless steel, no magnetic stainless steel, low temperature stainless steel, high strength stainless steel.

There are nearly 100 kinds of stainless steel that have been included in various standards in the world, and with the progress of science and technology and the development of industry and agriculture, the new stainless steel brand is still increasing. For a known grade of stainless steel, the chromium equivalent [Cr] and nickel equivalent [Ni] can be calculated according to its chemical composition, and the microstructure and properties of the steel can be roughly estimated by Schaeffler-Delong stainless steel microstructure diagram.

Matrix classification

1. Ferritic stainless steel. Chromium 12% ~ 30%. Its corrosion resistance, toughness and welderability are improved with the increase of chromium content, and its resistance to chloride stress corrosion is better than other kinds of stainless steel.

2. Austenitic stainless steel. Chromium content is more than 18%, but also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good comprehensive performance, can withstand the corrosion of a variety of media.

3. Austenitic - ferrite duplex stainless steel. It has the advantages of austenitic and ferritic stainless steel and has superplasticity.

4. Martensitic stainless steel. High strength, but poor plasticity and weldability.