What is 18/8 stainless steel
18/8 stainless steel is also known as 304 stainless steel, refers to the chemical composition of steel containing 18% chromium (Cr) and 8% nickel (Ni). Steel containing 18% chromium and 8% nickel includes 304 and its variants 304L, 304N and 304LN. 18/8 steel is the most widely used material, it has excellent corrosion resistance in mild environments and has good weldability and mechanical properties.
Properties of 18/8 stainless steel
The tables below list the properties of 18/8 stainless steel, including chemical composition, physical and mechanical properties. For complete datasheet and specifications, see AISI 304, 304L.
Chemical composition
The composition of 18-8 stainless steel is given in the table below.
| Chemical composition, % | ||||||||||
| ASTM | AISI (UNS) | C, ≤ | Yes, ≤ | Mn, ≤ | P, ≤ | S, ≤ | Cr | No | N, ≤ | products |
| ASTM A240/A240M | 304 (UNS S30400) | 0.07 | 0.75 | 2:00 | 0.045 | 0.030 | 17.5-19.5 | 8.0-10.5 | 0.10 | Plate, Sheet and Strip |
| ASTM A276A/276M | 0.08 | 1.00 | 2:00 | 0.045 | 0.030 | 6pm-8pm | 8.0-11.0 | – | Bars and Shapes | |
Mechanical properties
The tables below list the mechanical properties of 18-8 stainless steel, including yield strength, tensile strength, elongation and hardness, etc.
| Mechanical properties | |||||||||
| ASTM type | AISI (UNS) | Tensile strength, (MPa), ≥ | Yield strength, ≥ (MPa) with 0.2% displacement | Elongation by 50 mm (%, ≥) | Area Reduction, %, ≥ | Brinell hardness, (HBW) ≤ | Rockwell hardness, (HRBW) ≤ | products | Illness |
| ASTM A240/A240M | 304 (UNS S30400) | 515 | 205 | 40 | – | 201 | 92 | Plate, Sheet and Strip | – |
| ASTM A276A/276M | 515 | 205 | 40 | 50 | – | – | Bars and Shapes | Hot finished | |
| 620 | 310 | 30 | 40 | – | – | Cold finished, diameter ≤ 12.7 mm | |||
| 515 | 205 | 30 | 40 | – | – | Cold finished, Dia. > 12.7 mm | |||
Physical properties
Physical properties of 18-8 stainless steel, including density, melting point, magnetic capacity, specific heat capacity, electrical resistivity, modulus of elasticity (modulus of elasticity), thermal diffusivity, thermal conductivity and coefficient of thermal expansion.
Grades:
- 10 -6 ·K -1 = 10 -6 /K
- 1Ω mm²/m = 1 μΩ m
- 1 g/cm3 = 1 kg/dm3 = 1000 kg/m3
- 1 GPa = 1kN/mm2
- 1 MPa = 1 N/mm2
| 18-8 Physical Properties of Steel | |
| Density, g/cm3 (lb/in3) | 7.93 (0.286) |
| Melting point, °C (°F) | 1400-1450 (2550-2650) |
| Specific heat capacity, J/kg·K (Btu/lb ·°F) | 500 (0.12) at 20°C (68°F) |
| Electrical resistivity, μΩ·m | 0.72 at 20°C (68°F) |
| Conductivity, %, IACS | 2.5 |
| Magnetic permeability | 1.02 (approximate) |
| Elastic Modulus (Modulus of Elasticity), GPa (10 6 psi) | 193 (28) |
| Thermal diffusivity, mm2/s (in2/s) | 3.84 (0.006) |
| Thermal conductivity, W/m·K (Btu/ft·h·°F) | 16.2 (9.4) at 100°C (212°F) |
| 21.5 (12.4) at 500°C (932°F) | |
| Coefficient of thermal expansion (CTE), 10 -6 /K (μin./in·°F) | 17.2 (9.6) at 0-100°C (32-212°F) |
| 17.8 (9.9) at 0-315°C (32-600°F) | |
| 18.4 (10.2) at 0-538°C (32-1000°F) | |
Forms
18/8 stainless steel is widely used in the petroleum and chemical industry, metallurgical machinery, aerospace industry, food processing equipment, instruments, household appliances and hardware manufacturing industries.
18/8 steel is processed into many intermediate products, such as steel sheets and sheets, steel tubes and pipes, steel bars and flats, rods and wires, etc.
Final products such as all kinds of kitchen utensils, tableware, medical devices, machinery and parts, wire mesh, filters, architectural and decorative metal products, etc.
| Stainless steel equivalent grade 18-8 | |||||||||||||||||
| USA | European Union | ISO | Japan | China | Australia | India | Russia | Korea | |||||||||
| Standard | Type | Standard | Class (Steel Number) | Standard | Note (ISO number) | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note |
| AISI-SAE; ASTM A276/A276M; ASTM A240/A240M; |
304 (UNS S30400) |
EN 10088-1; EN 10088-2; EN 10088-3 | X5CrNi18-10 (1.4301) | ISO 15510 | X5CrNi18-10 | JIS G4303; JIS G4304; JIS G4305; | SUS304 | GB/T 20878; GB/T 1220; GB/T 3280 |
0Cr18Ni9; 06Cr19Ni10 (New designation) |
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| 304L (UNS S30403) |
X2CrNi18-9 (1.4307); X2CrNi19-11 (1.4306) |
X2CrNi19-11 (4306-304-03-I) | SUS304L | 00Cr19Ni10; 022Cr19Ni10 (New name) |
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