There are many types of stainless steel, which are mainly classified according to their organizational structure and alloying elements. The following are some common types of stainless steel and their properties:
Austenitic stainless steel: the most common type of stainless steel, containing high levels of chromium (usually 18%) and nickel (at least 8%). Examples include 302. 304. and 316. austenitic stainless steels offer excellent weldability, superior corrosion resistance, and good cold working properties.
Ferritic Stainless Steels: Contain lower levels of nickel than austenitic stainless steels and are usually nickel-free. Ferritic stainless steels are less resistant to pitting against chlorides, but are cheaper than austenitic stainless steels in some environments. An example is type 430.
Martensitic Stainless Steel: Contains about 0.1-1.0% carbon and can be hardened by heat treatment. Due to the higher carbon content, the hardness and strength will be higher than austenitic stainless steel and ferritic stainless steel, but the corrosion resistance is poor. For example, 410. 420 type.
Duplex stainless steel: contains the main austenite and a certain proportion of ferrite, the properties of these two phases complement each other, so that the duplex steel than a single-phase stainless steel has better mechanical properties and corrosion resistance. For example, 2205.
Precipitation hardening stainless steel: Containing both austenite and martensite characteristics, through precipitation hardening to form Ni3Al and other reinforcing phases, improve the strength and hardness. For example, 17-4PH.
Characteristics, the main characteristics of stainless steel include:
Corrosion resistance: the main advantage of stainless steel, especially in wet and salty environments.
Machinability: In general, austenitic stainless steels have better machinability than other types of stainless steel.
Strength and hardness: different types of stainless steel can achieve different strengths and hardnesses after heat treatment and cold working.
Wear resistance: some stainless steel types such as austenitic stainless steel can improve its surface hardness after cold working.
Weldability: Generally austenitic stainless steels have good weldability, but some types of stainless steels may require solution annealing after welding to restore corrosion resistance.
The choice of stainless steel material depends on the specific application requirements, cost considerations and the mechanical and chemical properties required.
