18/8 Stainless Steel vs 304: Composition, Properties and Applications

What Is 18/8 Stainless Steel?

18/8 stainless steel is a chromium-nickel alloy that contains approximately 18% chromium and 8% nickel. The high nickel content stabilises a fully austenitic structure at room temperature, so the material is non-magnetic in the annealed condition and can be strengthened only by cold deformation rather than by heat treatment.

The name is a description of the composition rather than a formal specification. It describes the same family of austenitic stainless steel that industry designates Type 304 in the AISI/ASTM system, 1.4301 in the European system, and S30400 under the UNS numbering system. Because the descriptive name and the official grade describe the same alloy, the two terms are used almost interchangeably in purchasing and engineering documents.

The combination of corrosion resistance, formability, weldability and hygiene has made this family the most widely consumed stainless steel in the world, from kitchenware and architectural cladding to process equipment and fasteners.

Is 18/8 Stainless Steel the Same as 304?

For practical purposes, yes. In the industrial AISI system the alloy is called Type 304; in the European system it is known as 1.4301. There are small differences in the permitted carbon and manganese ranges between the various product standards, but for the great majority of users 18/8 and 304 behave identically and can be treated as the same material.

Table 1 summarises how the two names relate to each other.

Feature	AISI 304	18/8 stainless steel
Nature of the name	Official AISI/ASTM designation	Descriptive commercial name
UNS number	S30400	Not applicable, general classification
EN designation	1.4301	Equivalent to 1.4301
Chromium	18.0 - 20.0% (ASTM A240 / A276)	Approximately 18%
Nickel	8.0 - 11.0% (ASTM A240 / A276)	Approximately 8%
Carbon	≤ 0.07%	Approximately 0.08% maximum

Chemical Composition and Mechanical Properties

Table 2 gives the typical chemical analysis of the 18/8 family in both the European and the ASTM specification ranges. The narrow nickel range is what keeps the structure austenitic and non-magnetic.

Element	EN 1.4301 range (%)	ASTM A240 / A276 range (%)
Chromium (Cr)	17.50 - 19.50	18.00 - 20.00
Nickel (Ni)	8.00 - 10.50	8.00 - 11.00
Carbon (C)	≤ 0.07	≤ 0.08
Manganese (Mn)	≤ 2.00	≤ 2.00
Silicon (Si)	≤ 1.00	≤ 0.75
Phosphorus (P)	≤ 0.045	≤ 0.045
Sulfur (S)	≤ 0.015	≤ 0.030
Nitrogen (N)	≤ 0.10	≤ 0.10

Table 3 lists the typical mechanical properties in the annealed condition, which is the normal delivery condition for sheet, coil, plate and bar.

Property	Typical value
Tensile strength	≥ 515 MPa (75 ksi)
Yield strength (0.2% offset)	≥ 205 MPa (30 ksi)
Elongation in 50 mm	≥ 40%
Hardness	≤ 201 HB, ≤ 92 HRB
Modulus of elasticity	approx. 193 GPa (28 x 10⁶ psi)
Poisson's ratio	approx. 0.29
Density	7.93 g/cm³ (0.286 lb/in³)

Magnetism, Food Contact and Corrosion Behaviour

Magnetism. Because of the high nickel content, 18/8 (304) is austenitic and therefore non-magnetic in the annealed condition. Cold working, for example deep drawing a bowl or bending a handle, partially transforms the structure to martensite and produces weak magnetism at heavily deformed areas such as bends and corners.

Food contact. 18/8 stainless steel has good corrosion resistance and heat resistance and is widely used for food-contact products such as tableware, sinks and processing equipment. "Food grade" is not a separate alloy, however: it describes a material that is produced and finished to meet the relevant food-contact requirements and standards. Purchasers should therefore specify the applicable standard and surface finish rather than relying on the 18/8 name alone.

Corrosion behaviour. The chromium-rich passive film gives good resistance to atmospheric corrosion, fresh water, many organic chemicals and a wide range of foods. The grade is, however, susceptible to pitting and crevice corrosion in chloride-rich environments and to stress corrosion cracking at elevated temperature, so 316-type grades with molybdenum are preferred for marine and chemical service.

18/8 Compared with 18/10, 18/0 and 303

Feature	18/8 (Type 304)	18/0 (typically Type 430)	18/10/2 (Type 316)
Chromium	18%	16 - 18%	16 - 18%
Nickel	8%	None	10 - 14%
Molybdenum	None	None	2 - 3%
Magnetic response	Non-magnetic when annealed	Strongly magnetic	Non-magnetic when annealed
Typical use	Mixing bowls, cutlery, sinks	Economical knives, trays	Marine fittings, chemical plant

Grade 303 is a specialised variant within the same 18/8 family. Standard 18/8 steel, most commonly Grade 304, is optimised for corrosion resistance, weldability and formability, whereas 303 adds sulfur or selenium to maximise machinability for high-volume part production at the cost of some corrosion resistance and weldability.

Product Forms, Applications and Frequently Asked Questions

The grade is available as cold rolled sheet and coil, hot rolled plate, precision strip, seamless and welded tube, bar, wire and pre-cut circles for the cookware industry. Cold rolled sheet is commonly supplied in thicknesses from about 0.3 mm to 6.0 mm and widths from 1000 mm to 1500 mm in finishes such as 2B, BA, No.4, hairline and 8K mirror. Hot rolled plate is supplied from about 3.0 mm to 100 mm in thickness and 1500 mm to 2500 mm in width in the pickled No.1 finish.

Cooking and kitchenware: cookware, refrigerators, sinks, commercial food processing equipment and beverage machinery

Architecture and construction: handrails, door and window frames, exterior cladding and structural supports

Fasteners and hardware: heavy-duty screws, bolts, nuts and washers for humid environments

Medical and pharmaceutical: surgical instruments, sterilisation trays and medical cabinetry

Automotive and transport: exhaust systems, trim components, housings and fuel lines

Q: Is 18/8 stainless steel the same as 304?
For most purposes, yes. 18/8 is the descriptive name for the chromium-nickel alloy that is designated Type 304 in the AISI/ASTM system and 1.4301 in the European system.

Q: Is 18/8 stainless steel magnetic?
In the annealed condition it is non-magnetic because the structure is austenitic. Cold working can transform part of the structure locally and leave weak magnetism at bends and heavily formed areas.

Q: Is 18/8 stainless steel food safe?
It is widely used for food-contact products because of its corrosion resistance and easy cleaning. "Food grade" refers to meeting specific food-contact standards, so the applicable specification and surface finish should always be confirmed.

Q: What is the difference between 18/8 and 18/10?
Both contain about 18% chromium, but 18/10 contains roughly 10% nickel and, in the 18/10/2 form, 2% molybdenum. The extra nickel and molybdenum give better corrosion resistance, which is why 316-type material is used in marine and chemical service.

Q: What is 18/0 stainless steel?
18/0 indicates approximately 18% chromium and no nickel, typically a ferritic Type 430. It is strongly magnetic and less corrosion resistant than 18/8, but it is a lower-cost option for dry or mild indoor applications.

Q: How does 303 stainless steel compare with 18/8?
303 belongs to the same austenitic 18/8 family but contains added sulfur or selenium to improve machinability. It is easier to machine but has lower corrosion resistance and is more difficult to weld than 304.