304 stainless steel is a common stainless steel material, the density of 7.93 g/cm³; It is also known in the industry as 18/8 stainless steel, which means it contains 18% or more chromium and 8% or more nickel; High temperature resistance of 800℃, with good processing performance, high toughness, widely used in industry and furniture decoration industry and food and medical industry. But it should be noted that food grade 304 stainless steel compared with ordinary 304 stainless steel, its content index is more strict. For example: basically the international definition of 304 stainless steel is mainly containing chromium 18%-20% nickel 8%-10%, but food grade 304 stainless steel is containing chromium 18% and nickel 8%, allow a certain range of fluctuations, and limit the content of various heavy metals. In other words, 304 stainless steel is not necessarily food grade 304 stainless steel.

304 is a universal stainless steel, which is widely used in the manufacture of equipment and parts requiring good comprehensive properties (corrosion resistance and formability). To maintain the corrosion resistance inherent in stainless steel, the steel must contain at least 18% chromium and at least 8% nickel. 304 stainless steel is a brand of stainless steel produced in accordance with ASTM standards in the United States.

Physical properties of SS304

Tensile strength σ B (MPa)≥515-1035

Conditional yield strength σ0.2 (MPa)≥205

Elongation δ5 (%)≥40

Hardness: 201 HBW or less; 92 HRB or less; 210 hv or less

Density (20℃, g/cm³) : 7.93

Melting point (℃) : 1398~1454

Specific heat capacity (0~100℃, KJ·kg-1K-1) : 0.50

Thermal conductivity (W·m-1· k-1) :(100℃) 16.3, (500℃) 21.5

Linear expansion coefficient (10-6· k-1) :(0~100℃) 17.2, (0~500℃) 18.4

Resistivity (20℃, 10-6 ω ·m2/m) : 0.73

Longitudinal elastic modulus (20℃, KN/mm2) : 193

304 stainless steel product standards 

For 304 stainless steel, the Ni element in its composition is very important, directly determines the corrosion resistance of 304 stainless steel and its value.

The most important elements in 304 are Ni and Cr, but they are not limited to them. Specific requirements are specified in the product standard. The common determination of the industry that as long as the Ni content is greater than 8%, Cr content is greater than 18%, can be considered 304 stainless steel. This is why the industry will call this type of stainless steel 18/8 stainless steel. In fact, the relevant product standards for 304 have very clear provisions, and these product standards for different shapes of stainless steel and some differences. Below are some common product standards and tests.

To determine whether a material is 304 stainless steel, must meet the requirements of every element in the product standards, as long as there is a does not meet, it can not be called 304 stainless steel.