Description
304 is the most commonly used stainless steel, even almost become synonymous with stainless steel.
In general, when we fastener industry (especially) about 304, refers to the 304 brands from ASTM A276 standard, or from JIS standard of SUS304 G4303 brand, because the two composition is the same, so everyday description is not too strict distinction between 304 and SUS304, Or will the two objects as the same standard.
The chemical composition of SUS304 stainless steel
SUS304 chemical composition (JIS G4303):
| Item | The element name and chemical composition (%) | |||||||
| C | Mn | Si | P | S | Ni | Mo | Cr | |
| SUS304 | ≤0.08 | ≤2.00 | ≤1.00 | ≤0.045 | ≤0.03 | 8.00-10.5 | – | 18.00-20.00 |
The above molybdenum is non-essential element. Fastener industry in our country, 304 raw materials sometimes deliberately add molybdenum and copper, which is to increase the corrosion of molybdenum, copper is conducive to the effect of cold pier shape.
The physical properties of SUS304 stainless steel
The mechanical properties of 304 stainless steel (JIS G4303) :
| Material | strength of extension σb (MPa) | offset yield strength σ0.2 (MPa) | elongation δ5 (%) | reduction of area ψ (%) | hardness | density 20℃ g/cm3 | fusing point（℃） |
| SUS304 | ≥520 | ≥205 | ≥40 | ≥60 | ≤187HB，≤90HRB，≤200HV | 7.93 | 1398~1454 |
Other physical properties of 304 stainless steel:
Melting point (℃) : 1398 ~ 1454
Specific heat capacity (0-100 ℃, KJ·kg-1 k-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
Electrical resistivity (20℃, 10-6Ω·m2/m) : 0.73
The longitudinal elastic modulus (20 ℃, KN/was) : 193
Application of 304 stainless steel
AISI 304 stainless steel is widely used in food industry, home appliances and consumer electronics, medical equipment, building decoration, hardware tools, automotive industry, petrochemical industry, water treatment plants, aerospace and so on. The following table lists typical uses by industry:
Electronic appliances: SS 304 liner, washing machine drum, watch mobile phone shell, microwave oven, range hood, control cabinet, water pump shell, etc.
Water treatment plant: valves, flanges, water pipes, water purification equipment.
Medical equipment: such as surgical instruments, medical equipment, etc.
Chemical equipment: used to make containers, pipes, valves, etc.
Food processing equipment, such as food processing machinery, food and transportation equipment, etc.
Automobile manufacturing: used in automobile parts, exhaust system, etc.
Power industry: used to manufacture power generation equipment, transmission lines, etc.
Marine engineering: used to make ship parts, offshore platforms, etc.
Furniture manufacturing: such as furniture hardware accessories, furniture surface decoration, etc.
Equipment manufacturing: such as instrument, optical instrument, etc.
Processing performance of 304 stainless steel
Plasticity: 304 stainless steel has good plasticity, easy to cold and hot processing, can be formed by forging, stretching, bending and other ways.
Weldability: 304 stainless steel has good weldability, can be through common welding methods such as arc welding, gas shielded welding and other welding processing, welded joint strength, good corrosion resistance.
Cutting machining: 304 stainless steel in the machining performance in general, but also can be in the form of turning, milling, drilling and precision machining, high precision parts.
Heat treatment: 304 stainless steel can improve its toughness and reduce hardness and strength through solid melting treatment, suitable for some engineering applications such as pipeline valves.
