Stainless steel is classified into austenitic stainless steel, ferritic stainless steel, duplex stainless steel, martensitic stainless steel and precipitation hardening stainless steel according to its structure.
First, austenitic stainless steel
Austenitic stainless steel is the most important type of stainless steel, and its output and dosage account for 70% of the total stainless steel. According to the alloying method, austenitic stainless steel can be divided into two categories: chrome-nickel steel and iron-chromium-manganese steel. The former uses nickel as the austenitizing element and is the main body of austenitic steel; the latter is a nickel-nickel steel that replaces expensive nickel with manganese and nitrogen.
Generally speaking, austenitic steel has good corrosion resistance, good comprehensive mechanical properties and process performance, but low strength and hardness.
Second, ferritic stainless steel
Ferritic stainless steel contains 11%-30% chromium, which is basically free of nickel. It is a nickel-nickel steel. In the state of use, the structure is mainly ferrite.
The ferritic stainless steel has higher strength and lower cold work hardening tendency, and is excellent in local corrosion resistance such as chloride stress corrosion resistance, pitting corrosion and crevice corrosion, but sensitive to intergranular corrosion and poor in low temperature toughness.
Third, duplex stainless steel
It is considered that austenite + ferritic duplex stainless steel can be referred to as having more than 15% of ferrite on the austenite matrix or 15% or more of austenite on the ferrite matrix.
Duplex stainless steel combines the advantages of austenitic steel and ferritic steel.
Fourth, martensitic stainless steel
Martensitic stainless steel is a type of steel that can be adjusted by heat treatment to have high strength and hardness.
Five, precipitation hardening stainless steel
The precipitation hardening type stainless steel is a steel which precipitates carbides in steel by heat treatment means to achieve strength improvement.
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