Yield strength (N/mm2) ≥ 205 Tensile strength ≥ 520 Elongation (%) ≥ 40 Hardness HB ≤ 187 HRB ≤ 90 HV ≤ 200 Density 7.93 g · cm-3 Specific heat c (20 ℃) 0.502 J · (g · C) - 1 Thermal conductivity λ/ W (m · ℃) - 1 (at the following temperature/℃) 20 100 500 12.1 16.3 21.4 Coefficient of linear expansion α/ (10-6/℃) (between the following temperatures/℃) 20～10020～200 20～300 20～400 16.0 16.8 17.5 18.1 Resistivity 0.73 Ω · mm2 · m-1 Melting point 1398~1420 ℃ As stainless and heat-resistant steel, 304 steel pipe is the most widely used equipment for food, general chemical equipment and atomic energy industry. 304 steel pipe is a kind of universal stainless steel pipe, which is widely used to make equipment and parts requiring good comprehensive performance (corrosion resistance and formability). 304 steel pipe has excellent rust and corrosion resistance and good intergranular corrosion resistance. 304 steel pipe material has strong corrosion resistance in nitric acid below boiling temperature with concentration ≤ 65%. It also has good corrosion resistance to alkali solution and most organic and inorganic acids. A kind of high alloy steel that can resist corrosion in the air or in the chemical corrosion medium. Stainless steel is a kind of steel that has beautiful surface and good corrosion resistance. It does not need to undergo surface treatment such as color plating, but gives full play to the inherent surface properties of stainless steel. It is used in many aspects of steel, usually called stainless steel. High alloy steels such as 13 chromium steel and 18-8 chromium-nickel steel are representative of properties. As stainless and heat-resistant steel, 304 steel pipe is the most widely used equipment for food, general chemical equipment and atomic energy industry.