AISI 304 / EN 1.4301 Stainless Steel: Equivalents, Properties and Applications

Introduction

AISI 304, known in Europe as EN 1.4301 or X5CrNi18-10, is the benchmark 18-8 chromium-nickel austenitic stainless steel. It combines excellent corrosion resistance in atmospheric and mild chemical service, good formability and weldability, hygienic surfaces and broad availability in every product form. For fabricators, engineers and buyers, the first step in specification is understanding how the same material is named across different national and regional systems.

Equivalent Designations

System	Designation
AISI / ASTM	304 (ASTM A240/A240M, UNS S30400)
EN (European)	1.4301, X5CrNi18-10 (EN 10088)
JIS (Japanese)	SUS304 (JIS G4303/G4304/G4305)
GB (Chinese)	06Cr19Ni10 (GB/T 20878, S30408)
BS (British)	304S15 / 304S31

Chemical Composition Comparison (wt%)

Element	AISI 304	EN 1.4301	JIS SUS304
Carbon, max	0.08	0.07	0.08
Chromium	18.0 - 20.0	17.5 - 19.5	18.0 - 20.0
Nickel	8.0 - 10.5	8.0 - 10.5	8.0 - 10.5
Manganese, max	2.0	2.0	2.0
Silicon, max	1.0	1.0	1.0
Phosphorus, max	0.045	0.045	0.045
Sulfur, max	0.030	0.030	0.030

Mechanical Properties

Property	Minimum / Range	Reference Standard
Tensile strength	515 MPa min (ASTM A240); 520-720 MPa (EN 10088-2)	ASTM A240 / EN 10088-2
Yield strength (0.2% offset)	205 MPa min (ASTM A240); 210 MPa min, t up to 8 mm (EN 10088-2)	ASTM A240 / EN 10088-2
Elongation	40% min (ASTM A240); 45% min (EN 10088-2)	ASTM A240 / EN 10088-2
Hardness	92 HRB / 201 HBW max (ASTM A240)	ASTM A240

Physical Properties

Property	Value
Density	7.93 g/cm3
Melting range	1400 - 1450°C
Thermal conductivity (20°C)	16.2 W/(m·K)
Mean thermal expansion (20-100°C)	17.3 x 10-6 /°C
Electrical resistivity	0.72 μΩ·m
Modulus of elasticity	about 200 GPa at 20°C

Corrosion Resistance

In atmospheric and most mild chemical environments, 304 exhibits excellent general corrosion resistance and is suitable for service below about 300°C where the atmosphere is not severely corrosive. It resists food acids, organic chemicals and many dilute inorganic media. Limitations appear in chloride-containing solutions, marine atmospheres and hot acids, where localized corrosion or stress corrosion cracking can occur; for such service, molybdenum-bearing grades such as 316/316L or higher alloys should be specified. Surface finish significantly affects performance: polished surfaces are more resistant than rough or scaled surfaces.

Welding

304 is readily welded by all conventional processes including TIG, MIG, MMA and resistance welding. Because standard 304 can sensitize in the heat-affected zone during welding, the low-carbon grade 304L (EN 1.4307) is preferred for heavy welded sections where post-weld solution annealing is not possible, or where the weldment will serve in corrosive media. Filler selection follows the base metal: ER308/ER308L filler is standard for joining 304.

Is AISI 304 Magnetic?

In the annealed condition, 304 is essentially non-magnetic. Cold working such as bending, drawing or rolling can transform some austenite to strain-induced martensite, producing slight magnetism; this is normal and does not indicate a material defect.

Typical Product Forms and Applications

304 is produced as plate, sheet, coil, strip, pipe, tube, bar, rod, wire, angle, channel and beam. Applications include food and beverage processing equipment, storage tanks, kitchen appliances, architectural panels and cladding, heat exchangers, pharmaceutical equipment, brewery and dairy plant, and general industrial piping and structures.

FAQ

Q1: What is the equivalent of EN 1.4301? EN 1.4301 (X5CrNi18-10) is equivalent to AISI 304, UNS S30400, JIS SUS304 and GB/T 06Cr19Ni10 (S30408).

Q2: What is the difference between AISI 304 and EN 1.4301? They are the same material designated in different systems. Minor differences exist in the specified maximum carbon (0.08% in AISI/JIS versus 0.07% in EN 10088) and chromium range, but the grades are interchangeable for practical purposes.

Q3: Which standard governs AISI 304 plate? ASTM A240/A240M covers plate, sheet and strip; seamless and welded pipe are covered by ASTM A312; bars by ASTM A276; and forgings by ASTM A182.

Q4: Should 304 or 304L be used for welded construction? For thin sections and non-corrosive service, 304 is adequate. For thick welded sections exposed to corrosive media, 304L (EN 1.4307) avoids sensitization and is the safer choice when post-weld annealing is impractical.

Q5: What temperature limit applies to 304? For continuous service in air, about 870°C is commonly used as the upper design limit, with oxidation accelerating above that; below 300°C, corrosion performance is the governing consideration rather than temperature.

Q6: Why does cold-worked 304 become slightly magnetic? Cold deformation induces strain-induced martensite in the metastable austenite; the effect is strongest in heavily drawn or rolled material and can be removed by solution annealing.