What Are the Differences Between 304 and 201 Stainless Steel?

201 vs 304: Two Families of Austenitic Steel

Both 201 and 304 are austenitic stainless steels, which means they have a face-centered cubic structure and are generally non-magnetic in the annealed state. The decisive difference is how they are alloyed. Grade 304, the modern 18-8 steel, uses 18-20% chromium and 8-10.5% nickel as its corrosion-resisting core. Grade 201 was developed to economize on nickel, the most expensive alloying element, by substituting 5.5-7.5% manganese and up to 0.25% nitrogen for part of the nickel, leaving 3.5-5.5% nickel. The result is a lower-cost steel with higher strength but lower corrosion resistance, so the choice between the two is a cost-versus-corrosion decision that must be made for each application.

Chemical Composition

The composition ranges below follow ASTM A240 for plate, sheet and strip and JIS G4304 for hot-rolled plates, with the designations SUS201 and SUS304.

Element	201 (UNS S20100) wt%	304 (UNS S30400) wt%
Chromium (Cr)	16.0-18.0	18.0-20.0
Nickel (Ni)	3.5-5.5	8.0-10.5
Manganese (Mn)	5.5-7.5	2.00 max
Carbon (C)	0.15 max	0.08 max
Nitrogen (N)	0.25 max	0.10 max
Silicon (Si)	0.75 max	0.75 max
Phosphorus (P)	0.060 max	0.045 max
Sulfur (S)	0.030 max	0.030 max
Iron (Fe)	Balance	Balance

Note that both grades carry the same 16-20% chromium family range; the significant differences are the lower nickel and much higher manganese and nitrogen of 201. The higher manganese and nitrogen compensate for the reduced nickel and increase the strength of 201.

Mechanical Properties

In the annealed condition, 201 is typically stronger and harder than 304, while 304 offers better ductility and formability.

Property (Annealed, typical)	201	304
Tensile Strength (MPa)	~620	~520
Yield Strength (MPa)	~275	~215
Elongation (%)	40	45-50
Hardness max (HRB)	95	92

201 also work-hardens more rapidly than 304 under cold forming, which can be an advantage for strength in some rolled or drawn products but a disadvantage in deep drawing and severe forming. Its density is about 7.93 g/cm3, essentially the same as 304.

Corrosion Resistance and Magnetism

Corrosion resistance is where the two grades diverge most. With 8-10.5% nickel and 18-20% chromium, 304 forms a stable passive film that resists atmospheric corrosion, food acids, and a wide range of chemicals, and it is the standard material for food-processing equipment, beverage lines and indoor and outdoor architectural components. The reduced nickel and high manganese of 201 give it only moderate corrosion resistance: acceptable in dry indoor conditions, but prone to pitting and rust staining in humid, coastal or chloride-containing environments. In terms of magnetism, 304 is essentially non-magnetic in the annealed state and only becomes slightly magnetic after heavy cold work, while 201 is noticeably more magnetic in the annealed condition because of its different austenite stability, and its magnetism increases further with cold working.

Applications and Selection Guidance

304 is the correct choice wherever hygiene, durability and corrosion resistance matter: food and beverage processing tanks and conveyors, kitchen equipment, chemical vessels, hospital furniture, railings and facades in coastal or humid climates, and automotive exhaust components that face high temperatures and road salt. 201 is a cost-effective alternative for indoor, dry applications where the environment is mild: interior furniture and trim, appliance frames, structural sections, roof gutters in sheltered locations, and components that can benefit from its higher strength. In automotive body and chassis applications, 201 offers high strength for frames and brackets in non-corrosive areas, but where rust resistance is critical, such as exhaust systems, 304 remains the standard. If the environment is wet, salty or chemically aggressive, specify 304 regardless of the cost saving.

FAQ

Which is better, 201 or 304?

For corrosion resistance, durability and food contact, 304 is better. 201 is better only on cost and in some cases on strength. The decision should be based on the service environment: wet, salty or acidic conditions demand 304; dry indoor and mild conditions can accept 201.

Why is 201 cheaper than 304?

201 contains only 3.5-5.5% nickel instead of 8-10.5%, and nickel is the most expensive alloying element in stainless steel. The gap is partly compensated by manganese and nitrogen, which are much cheaper.

Is 201 stainless steel magnetic?

Yes, noticeably more than 304. 201 has a less stable austenitic structure, so it shows measurable magnetic attraction in the annealed condition and becomes more magnetic after cold working. 304 is essentially non-magnetic when annealed.

Can 201 be used for food contact?

It is not recommended for food-processing equipment where corrosion resistance and hygiene are critical. 304 with its higher nickel content is the industry-standard grade for food and beverage contact because it withstands acids and cleaning agents far better than 201.

How can I tell 201 and 304 apart in practice?

No single field test is conclusive, but the differences in magnetism and price give clues: 201 attracts a magnet noticeably and is cheaper, while 304 barely attracts a magnet in the annealed state. For a reliable answer, request a mill test certificate with the chemical analysis, since the nickel and manganese contents are decisive.

Does 201 rust?

Yes, in humid, coastal or chloride-containing environments 201 is prone to pitting and surface rust staining because of its lower nickel content and reduced passive-film stability. In dry indoor environments it can perform adequately for years.