What is 304 stainless steel? Its composition, properties, and applications

304 stainless steel is a high heat-resistant stainless steel alloy with excellent corrosion resistance against many chemicals and industrial environments. With outstanding formability, 304 stainless steel is easy to weld and fabricate using all conventional methods. It is the most widely used stainless steel grade, commonly found in industrial systems and household equipment.

304 stainless steel is considered the standard industrial-grade material for corrosion-resistant applications both indoors and outdoors, including stainless steel fittings. SUS 304 stainless steel is also one of the most environmentally friendly materials due to its durability and recyclability. It can be easily bent, cut, and formed into various shapes for use in products like food containers, bowls, cookware, and thermal water bottles.

Whether you’re a materials expert or simply passionate about stainless steel, this article will cover everything you need to know about 304 stainless steel — a safe, long-lasting material for everyday life.

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What is 304 Stainless Steel?

304 stainless steel is an austenitic stainless steel alloy that contains approximately 18% chromium and 8% nickel, along with iron and trace elements. It has low magnetism, low thermal and electrical conductivity, and much higher corrosion resistance than regular steel.

Its superior formability makes it ideal for producing stainless steel products for both industrial and consumer use.

Grades of 304 Stainless Steel

304 stainless steel comes in two main variants: 304L and 304H. The primary difference lies in their carbon content, which slightly alters their properties. In practice, their unique characteristics become more evident depending on their application environments and service lifespan.

304 Stainless Steel

Standard 18-8 grade, containing approximately 18% chromium and 8% nickel. It is a highly versatile material suitable for a wide range of general-purpose applications. Depending on the carbon variation, 304 stainless steel can also offer improved heat resistance or other enhanced mechanical properties.

304L Stainless Steel

The “L” stands for “low carbon”, with a carbon content of around 0.03%. The lower carbon content minimizes or eliminates carbide precipitation during welding, making 304L ideal for corrosive environments where welding is required. Using 304L helps avoid post-weld treatments, saving time and labor.

304H Stainless Steel

The “H” indicates a high-carbon version of 304 stainless steel, designed for high-temperature service. It typically contains 0.04–0.10% carbon to improve strength at elevated temperatures above 427°C. 304H is usually dual certified as both 304 and 304H. It is non-magnetic in the annealed condition, though slight magnetism may occur after cold working or welding. 304H can be welded and fabricated using standard shop techniques and is both economical and highly corrosion-resistant.

Composition of 304 Stainless Steel

Types 304 / 304L / 304H are primary materials used for producing stainless steel accessories, components, and products designed to withstand harsh industrial environments. They are also commonly found in various everyday and structural applications due to their durability, corrosion resistance, and hardness. Additionally, their shiny surface contributes to the attractive appearance of 304 stainless steel products.

Below are the typical chemical compositions and physical properties of 304 stainless steel.

Chemical Composition of 304 Stainless Steel / 304L Stainless Steel / 304H Stainless Steel

Element304 Stainless Steel304L Stainless Steel 304H Stainless Steel
% CarbonMax 0.08Max 0.030.04 – 0.10
% ManganeseMax 2.0Max 2.0Max 2.0
% PhosphorusMax 0.045Max 0.045 Max 0.045
% SulfurMax 0.030Max 0.030Max 0.030
% SiliconMax 0.75Max 0.75Max 0.75
% Chromium18.0 – 20.018.0 – 20.018.0 – 20.0
% Nickel8.00 – 12.008.00 – 12.008.00 – 12.00
% Nitrogen0.00 – 0.110.00 – 0.110.00 – 0.10
% Iron (Fe)BalanceBalanceBalance

Properties of 304 Stainless Steel

Mechanical Properties of 304 Stainless Steel

The mechanical properties of 304 stainless steel refer to its resistance when subjected to external force. 304 stainless steel is both ductile and flexible, making it ideal for manufacturing and processing industrial stainless steel fittings. Even at very low temperatures, 304 stainless steel maintains its ductility. It has excellent bending, formability, and workability even without the need for heat treatment. For these reasons, 304 stainless steel has become the primary material in most industrial manufacturing fields.

Mechanical property indicators can be evaluated according to the manufacturing standards of each country or based on international standards. Commonly applied standards include TCVN, ISO, JS, AISI, etc.

  • Tensile strength: 515 MPa

  • Yield strength: 205 MPa

  • Elongation (in 50mm): 40%

  • Brinell hardness (HB): Max 201

  • Vickers hardness (HV): Max 92

Physical Properties of 304 Stainless Steel

304 stainless steel is a material with excellent corrosion resistance and high strength. It can be processed into hot-rolled sheets, cold-drawn tubes, and is non-magnetic. It performs exceptionally well against corrosion from environmental exposure or chemical agents. However, in chloride-containing environments, it may suffer from pitting or surface cracks. Stress corrosion cracking may also occur at temperatures above 60°C.

304 stainless steel offers excellent weldability, both with and without filler material. Recommended filler materials include 308 stainless steel, or 321 stainless steel if post-weld heat treatment is not feasible. For heavy-duty structural welding, 304L with filler is commonly used and requires post-weld annealing.

  • Density: approx. 8000 g/cm³

  • Melting point: 1400–1450°C

  • Specific heat: approx. 500 J/kg·°C

  • Electrical resistivity: approx. 720 μΩ·m at 20°C

  • Coefficient of thermal expansion: 17.02–18.4 × 10⁻⁶ /K

  • Thermal diffusivity: approx. 3.84 mm²/s

  • Thermal expansion: approx. 1.7–1.9 × 10⁻⁵ /K

  • Thermal conductivity: 16.2–21.5 W/m·K

Quality Standards for 304 Stainless Steel

The composition of 304 stainless steel varies by country due to different usage requirements, which results in variations in quality standards. These standards are applied nationally or regionally to unify industrial metal quality control.

  • JIS Standard: Japanese Industrial Standard

  • AISI Standard: American Iron and Steel Institute

  • ASTM/ASME Standard: American Society for Testing and Materials

  • GB Standard: Chinese Industrial Standard

  • DIN Standard: German Institute for Standardization

Surface Finishes of 304 Stainless Steel

  • No.1 Finish: Chemically cleaned and annealed after hot rolling. Recognizable by irregular patterns. Commonly used in cold rolling for industrial tanks and chemical equipment.

  • No.2D Finish: Dark, dull surface. Annealed and chemically treated after cold rolling without further polishing. Used widely in automotive, petrochemical plants, and construction due to lower cost.

  • 2B Finish: Processed from No.2D with additional polishing, giving it a smoother surface. Commonly used in all types of applications.

  • No.3 Finish: Polished with 100–120 mesh abrasives. Matte surface with medium reflectivity. Popular in construction, kitchen tools, and decorative uses.

  • No.4 Finish: Polished with 150–180 mesh abrasives. Brighter than No.3, with a silver-white finish. Frequently used in bathtubs, decorations, and food industry equipment.

  • BA Finish (Bright Annealed): Mirror-like shiny surface, annealed after cold rolling. Used in household applications such as mirrors, kitchenware, and ovens.

  • HL Finish (Hairline): Linear grain created by polishing brushes. Used for door frames and interior decorations.

  • Dull Finish: Matte, dull surface created by reducing gloss and applying a coarse finish similar to 2B. Rarely used in industrial sectors but preferred in interior design and elevator panels.

Popular 304 Stainless Steel Products on the Market

304 stainless steel is widely available in many forms and specifications. Below are the most commonly used 304 stainless steel products you should know:

  • 304 Stainless Steel Sheets

  • 304 Stainless Steel Coils

  • 304 Stainless Steel Tubes

  • 304 Stainless Steel Square Tubes

  • 304 Stainless Steel Bars

  • 304 Stainless Steel Mesh

  • 304 Stainless Steel Roofing Sheets

  • 304 Stainless Steel Wires

  • Colored 304 Stainless Steel

Common Methods to Identify 304 Stainless Steel

304 stainless steel is a difficult alloy to distinguish by appearance alone. Its outstanding physical and chemical properties make it the preferred material in many industrial applications, including the production and processing of stainless steel components. To accurately identify 304 stainless steel, several testing methods should be used to compare the material’s characteristics with known benchmarks. Below are three quick and commonly used methods for both professionals and non-specialists to identify 304 stainless steel:

1. Magnetic Test

Type 304 stainless steel is non-magnetic under normal conditions, meaning it does not exhibit magnetic attraction. When purchasing or inspecting stainless steel products, you can use a magnet to test the material. Place the magnet between a standard stainless steel piece and a suspected 304 stainless steel piece. Over time, the magnet will be attracted to the standard steel, not the 304 stainless steel.

2. Spark Test

Another method is to observe the sparks during cutting. When cutting 304 stainless steel with a grinder or cutting machine, if the sparks are few and light yellow, it may indicate the presence of 304. However, this method is not highly reliable as spark observation is subjective and difficult even for experienced professionals.

3. Acid Test

This is the most accurate test for identifying 304 stainless steel. Use a drop of sulfuric acid (H₂SO₄) or hydrochloric acid (HCl) on the surface of the steel. If there’s no reaction or the surface only turns slightly gray, it’s likely 304 stainless steel. If the material turns brick red, it may be a different stainless grade.

Applications of 304 Stainless Steel

304 stainless steel is widely used across nearly all industrial sectors. Its excellent formability and corrosion resistance—thanks to its high chromium and nickel content—make it ideal for both commercial and residential applications. It typically contains 18–20% chromium and 8–10.5% nickel by weight, giving it superior corrosion resistance and workability.

Common applications include:

  • 304 Stainless Steel Flanges

  • 304 Stainless Steel Fittings

  • 304 Stainless Steel Straps

  • 304 Stainless Steel Cable Ties

  • 304 Stainless Steel Welding Rods

  • 304 Stainless Steel Welding Wires

  • 304 Stainless Steel Valves

  • 304 Stainless Steel Tanks

  • 304 Stainless Steel Trim Profiles

  • 304 Stainless Steel Racks

  • 304 Stainless Steel Dining Tables

  • 304 Stainless Steel Pots

  • 304 Stainless Steel Hospital Beds

  • 304 Stainless Steel Kitchen Sinks

Frequently Asked Questions About 304 Stainless Steel

To help users better understand 304 stainless steel, we’ve compiled answers to 10 commonly asked questions:

1. What is the difference between 304 and 430 stainless steel?

304 is mostly non-magnetic and has weak magnetism, while 430 is ferritic and strongly magnetic.

2. What is the difference between 304 and 201 stainless steel?

201 has about 2% less chromium than 304, resulting in lower corrosion resistance. It also contains more manganese, making its surface appear darker.

3. What is the difference between 304 and 316 stainless steel?

316 contains 2–3% molybdenum, which 304 does not have. While 304 has 18% chromium and 8% nickel, 316 typically has 16% chromium and 10% nickel, giving 316 superior corrosion resistance.

4. Which is better: 304 or 316 stainless steel?

It depends on the application. 304 is easier to machine and suited for general use, while 316 is better for corrosive environments like saltwater or acidic conditions.

5. Is 304 stainless steel magnetic?

304 is generally non-magnetic, though it may exhibit slight magnetism due to cold working or impurities.

6. Can 304 stainless steel be corroded by acid?

304 is stable in oxidizing environments. It can resist concentrated sulfuric and nitric acids but is not resistant to hydrochloric acid or diluted sulfuric acid.

7. Is 304 stainless steel electrically conductive?

Like all stainless steels (201, 304, 430), 304 is conductive, but to a lower degree than carbon steel or copper.

8. Does 304 stainless steel rust?

It resists rusting in most environments including air, water, and mild acids. It’s suitable for use in lightly corrosive environments.

9. What is 304 2B stainless steel?

This is a standard finish obtained from 2D with additional polishing, resulting in a smooth, reflective surface. It’s widely used in various applications.

10. What is 304 BA stainless steel?

Bright Annealed (BA) 304 has a mirror-like surface, achieved through annealing after cold rolling. It’s often used in household items like mirrors, cookware, and in construction.

Contact Orinoxsteel for 304 Stainless Steel Pricing

Orinoxsteel is one of the leading stainless steel suppliers with decades of experience in material supply and accessories manufacturing. We provide a full range of 304 stainless steel products and serve customers globally. Our commitment to quality and mutual growth makes us a trusted partner for your stainless steel needs.

For pricing inquiries or product consultation, please contact our support team via hotline or email. We’re ready to assist you promptly with any 304 stainless steel questions or order requests.