Stainless steel is a type of steel that contains iron (Fe) and chromium (Cr), as well as other elements, such as carbon ©, silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), nickel (Ni), molybdenum (Mo), titanium (Ti), nitrogen (N) and copper (Cu). There are many types of stainless steel, which can be classified according to their crystal structure and chemical composition, such as austenitic, martensitic, ferritic, duplex, etc. In this blog, I will introduce a common stainless steel: SUS304L, which belongs to austenitic type and has good corrosion resistance and heat resistance.

What is the Chemical Composition of SUS304L?

SUS304L is a Japanese standard for stainless steel, which is equivalent to 304L in American standard (UNS S30403) and 022Cr19Ni10 in Chinese standard. SUS304L is a low-carbon version of SUS304 stainless steel, which has better corrosion resistance and heat resistance than SUS304. It also has good weldability and formability, suitable for various applications that require high temperature and pressure conditions.

The main chemical composition of SUS304L stainless steel is as follows:

ElementContent (%)
C≤0.03
Si≤1.00
Mn≤2.00
P≤0.045
S≤0.030
Cr18.0-20.0
Ni8.0-12.0
  

The carbon content of SUS304L stainless steel is less than 0.03%, which reduces the risk of intergranular corrosion caused by carbide precipitation at high temperatures. The chromium content of SUS304L stainless steel is between 18% and 20%, which forms a protective oxide layer on the surface of the steel, which prevents further corrosion by oxygen, water and other substances. The nickel content of SUS304L stainless steel is between 8% and 12%, which stabilizes the austenitic structure of the steel, which enhances its ductility, toughness and resistance to stress corrosion cracking.

Besides the main elements, SUS304L stainless steel may also contain some trace elements, such as nitrogen (N), copper (Cu), molybdenum (Mo), titanium (Ti), etc. These elements may have some effects on the properties of SUS304L stainless steel, such as improving its pitting resistance, crevice corrosion resistance, formability, etc.

In conclusion, the chemical composition of SUS304L stainless steel is mainly composed of carbon ©, silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr) and nickel (Ni), which determine its corrosion resistance, heat resistance, weldability and formability. The chemical composition of SUS304L stainless steel can be measured by various methods, such as spectroscopy, chemical analysis, etc.

What are the Mechanical Properties of SUS304L?

The mechanical properties of SUS304L stainless steel depend on the heat treatment condition, such as annealing, quenching, tempering, etc. The typical mechanical properties of SUS304L stainless steel in annealed state are as follows:

PropertyValue
Tensile strength (MPa)≥480
Yield strength (MPa)≥175
Elongation (%)≥40
Hardness (HB)≤187

The tensile strength of SUS304L stainless steel is the maximum stress that the steel can withstand before breaking in tension. The yield strength of SUS304L stainless steel is the stress that causes a permanent deformation of 0.2% in the steel. The elongation of SUS304L stainless steel is the percentage of increase in length that the steel can undergo before breaking in tension. The hardness of SUS304L stainless steel is the resistance of the steel to indentation by a hard object.

Besides the typical mechanical properties, SUS304L stainless steel may also have some other mechanical properties, such as fatigue strength, creep strength, impact toughness, etc. These properties describe the behavior of the steel under cyclic loading, high temperature loading, sudden loading, etc. These properties may vary depending on the testing methods and conditions.

In conclusion, the mechanical properties of SUS304L stainless steel are the characteristics of the steel that describe its behavior under various forces. The mechanical properties of SUS304L stainless steel depend on its chemical composition, microstructure, heat treatment condition, etc. The mechanical properties of SUS304L stainless steel can be measured by various methods, such as tensile test, hardness test, impact test, etc.

What are the Physical Properties of SUS304L?

The physical properties of SUS304L stainless steel are related to the temperature and magnetic field. The typical physical properties of SUS304L stainless steel at room temperature are as follows:

PropertyValue
Density (g/cm3)7.93
Melting point (℃)1398-1454
Specific heat capacity (J/kg·K)500 at 20℃
Electrical resistivity (μΩ·m)0.73 at 20℃
Elastic modulus (GPa)193 at 20℃
Thermal conductivity (W/m·K)16.3 at 100℃
Coefficient of thermal expansion (10-6/K)17.2 at 0-100℃

The density of SUS304L stainless steel is the mass per unit volume of the steel. The melting point of SUS304L stainless steel is the temperature at which the steel changes from solid to liquid state. The specific heat capacity of SUS304L stainless steel is the amount of heat required to raise the temperature of one kilogram of the steel by one degree Celsius. The electrical resistivity of SUS304L stainless steel is the measure of how strongly the steel resists the flow of electric current. The elastic modulus of SUS304L stainless steel is the measure of how stiff the steel is when subjected to elastic deformation. The thermal conductivity of SUS304L stainless steel is the measure of how fast the steel transfers heat through itself. The coefficient of thermal expansion of SUS304L stainless steel is the measure of how much the steel expands or contracts when heated or cooled.

SUS304L stainless steel is non-magnetic or weakly magnetic in annealed state, but it may become slightly magnetic due to cold working or welding. This is because SUS304L belongs to austenitic stainless steel, which has a face-centered cubic crystal structure, while magnetism is related to the unpaired electrons in the atoms.

In conclusion, the physical properties of SUS304L stainless steel are the characteristics of the steel that describe its state and response to physical stimuli. The physical properties of SUS304L stainless steel depend on its chemical composition, crystal structure, atomic arrangement, etc. The physical properties of SUS304L stainless steel can be measured by various methods, such as density meter, thermometer, calorimeter, ohmmeter, tensile tester, thermal conductivity meter, dilatometer, etc.

What is the Application of SUS304L?

SUS304L stainless steel has good corrosion resistance and heat resistance, suitable for equipment and parts under high temperature and pressure conditions. It also has good weldability and formability, suitable for deep drawing and polishing. Some typical applications of SUS304L stainless steel are:

  • Chemical equipment and piping: SUS304L stainless steel can resist the corrosion of various acids, alkalis, salts and other chemicals, and can withstand the high temperature and pressure in the chemical processes. SUS304L stainless steel can also be welded and formed easily, which makes it convenient to manufacture and install the equipment and piping.
  • Heat exchangers and boilers: SUS304L stainless steel can transfer heat efficiently and resist the scaling and oxidation at high temperatures. SUS304L stainless steel can also withstand the thermal stress and fatigue caused by the temperature changes in the heat exchangers and boilers.
  • Food processing and storage equipment: SUS304L stainless steel can resist the corrosion of food acids, juices, milk, etc., and can maintain its hygiene and cleanliness. SUS304L stainless steel can also be polished to a smooth and bright surface, which enhances its appearance and durability.
  • Medical equipment and instruments: SUS304L stainless steel can resist the corrosion of body fluids, blood, drugs, etc., and can prevent the bacterial growth and infection. SUS304L stainless steel can also be sterilized easily and safely, which makes it suitable for medical equipment and instruments.
  • Household appliances and utensils: SUS304L stainless steel can resist the corrosion of water, detergent, vinegar, etc., and can maintain its luster and beauty. SUS304L stainless steel can also be shaped into various forms and designs, which makes it suitable for household appliances and utensils.

In conclusion, SUS304L stainless steel has good corrosion resistance and heat resistance, suitable for equipment and parts under high temperature and pressure conditions. It also has good weldability and formability, suitable for various applications that require high quality and performance. SUS304L stainless steel is a common austenitic stainless steel that can be used in seawater, salt water, chemicals and other corrosive media.

Conclusion

SUS304L is a low-carbon version of SUS304 stainless steel, which has better corrosion resistance and heat resistance than SUS304. It also has good weldability and formability, suitable for various applications that require high temperature and pressure conditions. SUS304L is a common austenitic stainless steel that can be used in seawater, salt water, chemicals and other corrosive media.