AISI 304 (1.4301) Stainless Steel

What is AISI 304?

AISI 304 (1.4301) is a widely-used austenitic chromium-nickel stainless steel. It has excellent drawing properties and very good formability, while it is also highly corrosion-resistant. Typical uses of 304 stainless steel include sinks, kitchen equipment such as pans, tubing and much more.

Chemical Composition

AISI 304 typically contains 17.5-19.5% Chromium, 8-10.5% Nickel, 2% Manganese, 1% Silicon, 0.11% Nitrogen, 0.07% Carbon, 0.05% Phosphorus and 0.03% Sulphur.

Table

Element	Weight
Iron	66.74 - 71.24% (Balance)
Chromium	17.5 - 19.5%
Nickel	8 - 10.5%
Manganese	2%
Silicon	1%
Nitrogen	0.11%
Carbon	0.07%
Phosphorus	0.05%
Sulphur	0.03%

Equivalents and other designations

The following are all equivalents of AISI 304:

X5CrNi18-10, EN 1.4301, DIN 1.4301, UNS S30400, BS 304S15, BS 304S16, BS 304S31, BS EN58E

Properties

	304 (Typical values at 20°C)	304 Annealed (Typical values at 20°C)
Density	8 g/cm³
Elastic modulus	193 GPa	200 GPa
Hardness, Brinell	215 HB
Tensile strength	500-700 MPa	590 MPa
Yield strength	190 MPa	240 MPa
Elongation	40%
Coefficient of thermal expansion	1.72E-5 1/K
Thermal conductivity	16.2 W/(m·K)
Melting point	1450°C
Specific heat capacity	500 J/(kg·K)
Electrical resistivity	0.73 x 106 Ω·m

Corrosion resistance

AISI 304 is highly corrosion resistant to most oxidizing acids. However, corrosion can occur in environments containing chlorides. 304 stainless steel is not as corrosion-resistant as 316 stainless steel.

Machinability

AISI 304 has good machinability, however its low thermal conductivity means coolants and lubricants should be used liberally, especially on the cutting edges.

AISI 304 (1.4301) vs 316 (1.4401)

AISI 304 and 316 have similar values for hardness (Brinell), elastic modulus and tensile strength. AISI 316 has slightly higher yield strength at 200 MPa (vs. 190 MPa for 304), while AISI 304 has a slightly higher melting point (1450°C vs. 1400°C for 316). Due to the AISI 316 generally has better corrosion-resistance than 304.

Compare 304 and 316 stainless steel in more detail here: