There are various types of stainless steel depending on the ratio of alloys and the heat treatment applied, and they are roughly divided into three types: martensitic, ferrite, and austenitic.
Martensitic
Martensite structure is formed by heat treatment (quenching), and Stainless Steel 304 Pipe is made from it. Compared to others, it is inferior in corrosion resistance due to its low carbon content. Due to these properties, it is often used for products that require strength and hardness and products exposed to high temperatures.
Specifically, it is often used for blades, nozzles, turbine blades, brake discs, etc. The main martensitic stainless steels are SUS410 and SUS403.
Ferritic
It is a chrome-based stainless steel containing nickel and is resistant to corrosion in high-temperature environments against gases containing sulfur. It has the characteristics of not causing stress cracking due to chloride, which is a drawback of austenitic stainless steel.
On the other hand, the corrosion resistance is inferior to that of austenitic Stainless Steel 316 Pipe because nickel is not added. Still, there are cases where corrosion resistance and oxidation resistance are improved by adding Mo, Ti, Nb, Al, Si, etc.
The main ferritic stainless steel is SUS430, which is inexpensive and has good weldability, so it is also used for furnace parts and chemical equipment up to 800 ° C.
Austenitic
Unlike the other two types, austenitic Stainless Steel 316 Tube is the only chrome-nickel stainless steel. By adding two components, nickel and chromium, the oxide film's adhesion is increased, which makes it more resistant to rust and heat resistance. Although it has the disadvantage of being highly susceptible to stress corrosion cracking, some types have been improved by additive elements.
The main standards are SS 304 Sheet and SS 316 Sheet. It is known as stainless steel, which has the widest range of applications because it is superior to martensitic and ferritic stainless steels in corrosion resistance, workability, and weldability.
On the other hand, it is inferior to other strengths and hardness because it is not hardenable. It is used in many applications and is also used as a spring and tough steel due to its remarkable processing effect.
In this way, Stainless Steel 304 Tube is classified into various types according to the components contained in it, and the properties of each type differ. The difference in physical properties by type is as follows.
Precipitation hardening system
The strength of austenitic stainless steel cannot be increased by heat treatment, but the steel grade improved by precipitation. Thus, corrosion resistance is not as good as that of austenitic stainless steel, but it is superior to that of chrome stainless steel. It is a steel type that has been molded by solution heat treatment and subjected to precipitation heat treatment.
Austenitic stainless steels such as SUS304 and SUS316 have slightly different properties from the other two types.
The first major difference is the presence or absence of magnetism. Martensitic and ferritic stainless steels are magnetic, while austenitic stainless steels are not. However, even with austenitic stainless steel, which normally has no magnetism, the processed part may become magnetic when deformed by applying force such as bending.
