What are the key properties of Stainless Steel 304?

Stainless Steel 304 offers good corrosion resistance in atmospheric, food and beverage, and many chemical environments, is non-magnetic in the annealed condition, and is suited to sanitary and food contact applications. Annealed 304 has a minimum tensile strength of 515 MPa (about 600 MPa typical), a 193 GPa elastic modulus and at least 40% elongation, so it is tough rather than brittle.

How is Stainless Steel 304 CNC machined?

Stainless Steel 304 is machined from solid billet with precision cutting tools. It work hardens quickly and resists chip breaking, so it machines best with slower speeds, heavier feeds, good lubrication, sharp tooling and rigid setups. Typical tolerance is ±0.025 mm, down to ±0.010 mm on request, with an as-machined finish of Ra 1.6-3.2 µm or Ra 0.4 µm with a precision finish.

What are the common applications of Stainless Steel 304?

Stainless Steel 304 is used for food and beverage equipment such as sanitary fittings, manifolds and process hardware, for test fixtures and adapters, for laboratory equipment and medical fixtures that are cleaned and sterilized, and for corrosion resistant fasteners, brackets, consumer products and inland outdoor enclosures.

What are the advantages of using Stainless Steel 304?

Stainless Steel 304 resists corrosion in most everyday environments, is non-magnetic in the annealed condition, and is accepted for food and dairy equipment according to ATI. It responds well to polishing and electropolishing, keeps its toughness at cryogenic temperatures, and resists oxidation in air to 870 °C in intermittent service and 925 °C in continuous service.

Are there any limitations to Stainless Steel 304?

Stainless Steel 304 work hardens quickly, so it needs sharp tooling and rigid setups. It has lower strength than precipitation-hardened stainless alloys such as 17-4 PH and cannot be hardened by heat treatment, and its thermal conductivity is much lower than that of aluminium alloys. Warm chloride environments can cause pitting, crevice corrosion and stress corrosion cracking.

Can Stainless Steel 304 be used in marine environments?

ATI does not recommend Stainless Steel 304 for marine exposure, because sea water and warm chlorides cause pitting and crevice corrosion. Choose Stainless Steel 316L for marine and saltwater parts. For inland outdoor hardware, 304 is a proven choice: ATI notes that building facades in non-marine atmospheres make heavy use of 18-8 stainless steels such as 304.

Is Stainless Steel 304 magnetic?

Annealed Stainless Steel 304 is essentially non-magnetic, with a magnetic permeability of about 1.005 in ATI data. Cold work makes it slightly magnetic, raising the permeability to about 1.163 after 30% cold work, so heavily formed areas can attract a magnet.

CNC Machining Stainless Steel 304 For Corrosion-Resistant Parts

Get a quote Technical data

Stainless Steel 304 machined part example

CNC Machining

Tight Tolerances

CNC machining material

Stainless Steel 304 overview

Stainless Steel 304 is the most widely used stainless steel, CNC machined into parts that resist corrosion, clean easily and last. It stands up to inland outdoor air, foods, beverages, cleaning agents and many chemicals, is accepted for food and dairy contact, and polishes to a smooth, cleanable finish. It is tough rather than brittle, so fixtures and tooling survive daily handling. Food and beverage processors, medical and laboratory teams, and equipment designers use it for sanitary fittings, sterilizable fixtures, fasteners, brackets and outdoor enclosures.

How Stainless Steel 304 is manufactured

Stainless Steel 304 parts are made by CNC machining, which removes material from solid billet using precision cutting tools. Datum surfaces and planned fixturing let multi-setup parts reference every critical feature, so bores, threads, sealing faces and mounting patterns are cut to the drawing in the same job. Because there is no tooling to make, the same program runs a single prototype or a repeat production batch.

Machining envelope: 1000 × 600 × 500 mm
Lead time: 5-7 business days
Tolerance: ±0.025 mm typical

Forge Labs Steam

Know before you manufacture in Stainless Steel 304.

Upload CAD files and drawings to Forge Labs Steam, and our engineers review Stainless Steel 304 parts for tolerances, tool access and finish so issues are fixed before production.

Upload your file Chat with us

Industry applications

Industry applications for Stainless Steel 304

Stainless Steel 304 is the industry standard for corrosion resistant hardware, enclosures and food equipment, and the most frequently used alloy in the stainless steel family. It combines reliable resistance to atmospheric corrosion, foods and beverages and many organic and inorganic chemicals with a non-magnetic structure in the annealed condition, and it is suited to sanitary and food contact applications.

Medical, food and beverage programs trust it where uptime matters. Parts clean easily and keep product free from contamination, and 304 responds well to polishing and electropolishing for smooth, cleanable surfaces.

Engineering teams rely on machined Stainless Steel 304 for tight tolerances, and we machine around its fast work hardening so critical features stay on size from the first part to the last.

All industries

Aerospace
MRO Test Fixtures & Adapters
Test plates and fixtures with bores, threads and O-ring grooves machined to the drawing.
Food & Beverage
Sanitary Fittings & Process Hardware
Sanitary fittings, manifolds and process hardware in a stainless accepted for food and dairy contact.
Clean Tech & Power Generation
Engine & Valve Components
Seal protectors, valve parts and threaded fittings, with one lot shipped five days early.
Medical & Laboratory
Laboratory Fixtures & Sterilizable Tooling
Easy-to-clean surgical tooling and lab fixtures that stand up to routine cleaning and sterilizing.
Industrial Design
Enclosures, Fasteners & Consumer Hardware
Corrosion resistant fasteners, brackets and enclosures for inland outdoor use.

Printed stainless steel test-fixture body with machined ports, a seal seat and mounting lugs on a workshop bench

Aerospace

MRO Test Fixtures & Adapters

Engine MRO shops and test teams use machined stainless steel for test plates, maintenance fixtures and adapters. Stainless Steel 304 is tough rather than brittle, absorbing 200 J of Charpy impact energy at room temperature, which suits tooling that is handled, cleaned and returned to the bench. On one stainless engine-maintenance fixture, we machined the tapered pipe threads, handle thread and O-ring grooves to the drawing and finished the seal contact faces to 32 µin Ra (about 0.8 µm).

Engine test plates
Maintenance fixtures and adapters
Ported seal interfaces

Read the stainless test fixture case study

Stainless steel process line with sanitary tri-clamp fittings around a clear inline section

Food & Beverage

Sanitary Fittings & Process Hardware

Food, beverage and dairy processors use Stainless Steel 304 for sanitary fittings, manifolds and process hardware. It is accepted for food and dairy contact and is a standard material of construction in breweries, and food plants clean it with specially formulated caustic, phosphoric or sulfamic acid cleaners.

Sanitary fittings and manifolds
Valve bodies and process hardware
Brewery and dairy equipment parts

Explore clean tech manufacturing

Thread being tapped into a small printed stainless steel part held in a bench vise

Clean Tech & Power Generation

Engine & Valve Components

Engine and power generation developers use machined stainless steel for seal protectors, valve parts, counterweights and threaded fittings drawn for machining. Stainless Steel 304 resists oxidation in air to 870 °C in intermittent service, so it suits hot-running brackets and fittings. On one engine program, we cut the threads on stainless seal protectors, valve heads and counterweights after printing, and the seal protector lot shipped five business days ahead of the promised date.

Seal protectors and valve parts
Threaded counterweights
Threaded engine fittings

Read the DMLS engine parts case study

Touch probe measuring a machined bore on a stainless steel part on a granite inspection table

Medical & Laboratory

Laboratory Fixtures & Sterilizable Tooling

Medical device and laboratory teams use Stainless Steel 304 for surgical tooling, sterilizable fixtures and laboratory equipment that is cleaned and sterilized on a regular basis. It resists the cleaning agents those routines use and stays essentially non-magnetic in the annealed condition, with a magnetic permeability of 1.005. The device maker qualifies any part that contacts patients.

Surgical tooling
Sterilizable fixtures and assemblies
Laboratory equipment parts

Explore medical devices

Machined metal plate housing with an O-ring groove, threaded ports, a quick-connect fitting and a handle

Industrial Design

Enclosures, Fasteners & Consumer Hardware

Product and equipment designers use Stainless Steel 304 for corrosion resistant fasteners and brackets, consumer products and outdoor enclosures, where a part has to look good and last. Building facades in non-marine atmospheres make heavy use of 18-8 stainless steels such as 304.

Corrosion resistant fasteners and brackets
Outdoor enclosures and housings
Consumer product hardware

Explore industrial design

Performance data

Technical performance for Stainless Steel 304

Values for annealed Type 304: ASTM A240/A240M minimums, Outokumpu typical data, and Atlas Steels, ATI and Rolled Alloys alloy data, with the source listed with each property.

Compare with another material

Mechanical performance

Mechanical properties

Stainless Steel 304 delivers dependable strength and impact resistance for sanitary manifolds and fittings, corrosion resistant fasteners and brackets, and sterilizable fixtures and tooling. It yields and stretches well before it fractures instead of cracking, and it stays tough down to cryogenic temperatures.

The minimum rows are the ASTM A240 annealed values for plate; bar stock to A276 or A479 carries minimums set by its finish and size, and the typical rows show what annealed stock usually delivers. ATI, Outokumpu and Rolled Alloys list a slightly higher modulus, 200 GPa, than the Atlas value in the table. 304 cannot be hardened by heat treatment, but cold work raises its strength, and a smooth machined surface improves fatigue life while a corrosive environment reduces it.

PropertyValue

Tensile Strength, Annealed (minimum)ASTM A240/A240M: 515 MPa
Yield Strength Rp0.2, Annealed (minimum)ASTM A240/A240M: 205 MPa
Elongation at Break, Annealed (minimum, 50 mm)ASTM A240/A240M: 40 %
Hardness, Annealed (maximum)ASTM A240/A240M: 201 HB / 92 HRB
Tensile Strength, Annealed (typical)Outokumpu typical data (9.5 mm plate): 600 MPa
Yield Strength Rp0.2, Annealed (typical)Outokumpu typical data (9.5 mm plate): 290 MPa
Elongation at Break, Annealed (typical)Outokumpu typical data (9.5 mm plate): 58 %
Reduction of Area, Annealed (typical)Outokumpu typical data (9.5 mm plate): 70 %
Rockwell Hardness, Annealed (typical)Outokumpu typical data (9.5 mm plate): 82 HRB
Modulus of ElasticityAtlas Steels 304 data: 193 GPa
Poisson's RatioRolled Alloys 304/304L data: 0.30
Charpy V-Notch Impact Energy (23 °C / −196 °C)ATI 304 alloy data: 200 / 115 J

Material makeup

Physical properties

A uniform wrought structure machines consistently from part to part and takes downstream finishing predictably.

The composition rows are the specification limits. Chromium gives 304 its corrosion resistance and nickel its austenitic structure. The salt spray result shows how the alloy handles a neutral salt fog, which does not predict service in sea air or sea water.

PropertyValue

DensityAtlas Steels 304 data: 7.90 g/cm³
Neutral Salt Spray (5% NaCl, 100 h)ASTM B117 (ATI data): No rusting or staining
Chromium (Cr)ASTM A240/A240M: 17.5–19.5 %
Nickel (Ni)ASTM A240/A240M: 8.0–10.5 %
Carbon (C)ASTM A240/A240M: ≤ 0.07 %
Manganese (Mn)ASTM A240/A240M: ≤ 2.00 %
Silicon (Si)ASTM A240/A240M: ≤ 0.75 %
Phosphorus (P)ASTM A240/A240M: ≤ 0.045 %
Sulfur (S)ASTM A240/A240M: ≤ 0.030 %
Nitrogen (N)ASTM A240/A240M: ≤ 0.10 %

Heat performance

Thermal properties

Food, medical and process equipment in Stainless Steel 304 handles repeated heating, washing and cooling without losing its corrosion resistance or toughness. Its thermal expansion is relatively high for a metal, so allow for it in tight fits that run hot.

The service temperatures are oxidation limits in air, not load ratings, and strength falls as temperature rises. Avoid continuous use between about 425 °C and 860 °C where the part must later resist aqueous corrosion, and use the annealing range to restore softness and corrosion resistance after welding or heavy cold work.

PropertyValue

Melting RangeATI 304 alloy data: 1399–1421 °C
Thermal Conductivity (100 °C / 500 °C)Atlas Steels 304 data: 16.3 / 21.5 W/m·K
Coefficient of Thermal Expansion (0–100 / 0–315 / 0–538 °C)Atlas Steels 304 data: 17.2 / 17.8 / 18.4 ×10⁻⁶/K
Specific Heat (0–100 °C)Atlas Steels 304 data: 500 J/kg·K
Maximum Service Temperature in Air, Intermittent (oxidation)Atlas Steels 304 data: 870 °C
Maximum Service Temperature in Air, Continuous (oxidation)Atlas Steels 304 data: 925 °C
Solution Annealing Temperature (cool rapidly)Atlas Steels 304 data: 1010–1120 °C

Functional performance

Electrical properties

Stainless Steel 304 conducts electricity, so machined housings, fixtures and functional prototypes can be grounded through the part, and the resistivity value gives engineers a reliable input for current flow and grounding calculations.

The permeability row shows how close annealed 304 is to non-magnetic. Cold work raises it, so heavily formed or cold-worked areas can become slightly magnetic.

PropertyValue

Electrical Resistivity (20 °C)Atlas Steels 304 data: 7.2×10⁻⁷ Ω·m
Magnetic Permeability (annealed / 30% cold worked)ATI 304 alloy data: 1.005 / 1.163

Compatibility data

Chemical properties

ATI gives corrosion rates in boiling solutions, and Outokumpu gives the temperature above which 304 corrodes faster than 0.13 mm a year. 304 resists dilute nitric, acetic and phosphoric acids well, while boiling dilute hydrochloric and sulfuric acids and hot strong caustic attack it.

Chlorides set the limit: pitting, crevice corrosion and stress corrosion cracking become likely in warm chloride solutions, and ATI recommends 316 for higher chloride levels, lower pH or higher temperatures. Use the ratings for screening and confirm them for your application.

ChemicalCorrosion rate when boiling (ATI)Exceeds 0.13 mm/a above (Outokumpu)

Acetic acid 20%: Corrosion rate when boiling (ATI)< 0.01 mm/a; Exceeds 0.13 mm/a above (Outokumpu)Not tested
Acetic acid 80%: Corrosion rate when boiling (ATI)Not tested; Exceeds 0.13 mm/a above (Outokumpu)100 °C (pitting)
Phosphoric acid 20%: Corrosion rate when boiling (ATI)< 0.03 mm/a; Exceeds 0.13 mm/a above (Outokumpu)Not tested
Phosphoric acid 85%: Corrosion rate when boiling (ATI)Not tested; Exceeds 0.13 mm/a above (Outokumpu)80 °C
Nitric acid 10%: Corrosion rate when boiling (ATI)Not tested; Exceeds 0.13 mm/a above (Outokumpu)Above boiling
Nitric acid 65%: Corrosion rate when boiling (ATI)0.2 mm/a; Exceeds 0.13 mm/a above (Outokumpu)100 °C
Formic acid 45%: Corrosion rate when boiling (ATI)1.4 mm/a; Exceeds 0.13 mm/a above (Outokumpu)Not tested
Formic acid 50%: Corrosion rate when boiling (ATI)Not tested; Exceeds 0.13 mm/a above (Outokumpu)10 °C or below
Hydrochloric acid 0.2%: Corrosion rate when boiling (ATI)Not tested; Exceeds 0.13 mm/a above (Outokumpu)Above boiling
Hydrochloric acid 1%: Corrosion rate when boiling (ATI)2.5 mm/a; Exceeds 0.13 mm/a above (Outokumpu)30 °C (pitting)
Sodium hydroxide 50%: Corrosion rate when boiling (ATI)3.0 mm/a; Exceeds 0.13 mm/a above (Outokumpu)85 °C
Sulfamic acid 10%: Corrosion rate when boiling (ATI)3.7 mm/a; Exceeds 0.13 mm/a above (Outokumpu)Not tested
Sulfuric acid 10%: Corrosion rate when boiling (ATI)11.3 mm/a; Exceeds 0.13 mm/a above (Outokumpu)Not rated

Compliance

Compliance profile

Type 304 is specified under ASTM A240/A240M for plate, sheet and strip and under ASTM A276 and A479 for bar and shapes, with A479 covering bar for boilers and pressure vessels.

ATI states that Type 304 is accepted by the National Sanitation Foundation for food preparation and storage, and by the Dairy and Food Industries Supply Association sanitary standards committee for contact with dairy products. Food and dairy certification is held by the maker of the finished equipment, with 304 as an accepted material of construction.

StandardStatus

ASTM A240/A240M (UNS S30400)Plate, sheet and strip: chemistry and annealed minimums of 515 MPa tensile, 205 MPa yield and 40% elongation: Alloy specification
ASTM A276 / A479 (UNS S30400)Bar and shapes (A479 for boiler and pressure-vessel use); annealed minimums depend on the finish and bar size: Alloy specification
NSF food equipment acceptanceATI: Type 304 is accepted by NSF for food preparation and storage: ATI statement
Dairy contact acceptanceATI: accepted for contact with dairy products by the Dairy and Food Industries Supply Association Sanitary Standards Committee; a standard brewery material: ATI statement

Related materials

Compare Stainless Steel 304 with similar materials

Compare all materials

Resources

Datasheets and design resources

Datasheets, design guidance and supplier documentation for Stainless Steel 304.

Download center

Access the most recent datasheet and supporting documentation maintained by our engineering team.

Stainless Steel 304 datasheet

Design guidelines

Tolerance, wall thickness and finishing guidance for machined parts.

View machining guidance

Five-axis CNC machining centre with its enclosure door open and a part on the rotary table

Advanced Manufacturing

Built with Precision CNC Machining Technology

Stainless Steel 304 is manufactured using advanced CNC machining technology, ensuring optimal material properties and dimensional accuracy. Machined parts keep the wrought strength and corrosion resistance of the stock.

Surface finish: As-machined Ra 1.6-3.2 µm; precision finish Ra 0.4 µm
Production capacity: Large envelope for efficient manufacturing of multiple parts or assemblies
Quality control: In-process monitoring and batch traceability for consistent part quality and material properties
Colours & finishes: Deburring, passivation, electropolishing and bead blasting

Learn more about CNC machining

Frequently Asked Questions

Frequently asked questions about Stainless Steel 304

Can't find the answer you're looking for? Reach out to our customer support team.

: Stainless Steel 304 offers good corrosion resistance in atmospheric, food and beverage, and many chemical environments, is non-magnetic in the annealed condition, and is suited to sanitary and food contact applications. Annealed 304 has a minimum tensile strength of 515 MPa (about 600 MPa typical), a 193 GPa elastic modulus and at least 40% elongation, so it is tough rather than brittle.
: Stainless Steel 304 is machined from solid billet with precision cutting tools. It work hardens quickly and resists chip breaking, so it machines best with slower speeds, heavier feeds, good lubrication, sharp tooling and rigid setups. Typical tolerance is ±0.025 mm, down to ±0.010 mm on request, with an as-machined finish of Ra 1.6-3.2 µm or Ra 0.4 µm with a precision finish.
: Stainless Steel 304 is used for food and beverage equipment such as sanitary fittings, manifolds and process hardware, for test fixtures and adapters, for laboratory equipment and medical fixtures that are cleaned and sterilized, and for corrosion resistant fasteners, brackets, consumer products and inland outdoor enclosures.
: Stainless Steel 304 resists corrosion in most everyday environments, is non-magnetic in the annealed condition, and is accepted for food and dairy equipment according to ATI. It responds well to polishing and electropolishing, keeps its toughness at cryogenic temperatures, and resists oxidation in air to 870 °C in intermittent service and 925 °C in continuous service.
: Stainless Steel 304 work hardens quickly, so it needs sharp tooling and rigid setups. It has lower strength than precipitation-hardened stainless alloys such as 17-4 PH and cannot be hardened by heat treatment, and its thermal conductivity is much lower than that of aluminium alloys. Warm chloride environments can cause pitting, crevice corrosion and stress corrosion cracking.
: ATI does not recommend Stainless Steel 304 for marine exposure, because sea water and warm chlorides cause pitting and crevice corrosion. Choose Stainless Steel 316L for marine and saltwater parts. For inland outdoor hardware, 304 is a proven choice: ATI notes that building facades in non-marine atmospheres make heavy use of 18-8 stainless steels such as 304.
: Annealed Stainless Steel 304 is essentially non-magnetic, with a magnetic permeability of about 1.005 in ATI data. Cold work makes it slightly magnetic, raising the permeability to about 1.163 after 30% cold work, so heavily formed areas can attract a magnet.

Start a quote

Ready to Get Started with Stainless Steel 304?

Upload your design and get a quote for Stainless Steel 304 parts from our engineers.

Engineer-prepared quotes with manufacturability review
Production workflows built for repeatable quality
Engineering support from prototype to production

Compare all materials

Create an account to upload CAD

STEP, STL, OBJ, 3MF and IGES supported

Manufacturing technologies: 6
Engineering materials: 50+
Part quantities: 1-500+