what is 304 in ss304?

What is 304 in SS 304? A Clear Explanation

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply high-quality SS 304 plates compliant with ASME SA 240 and ASTM A240 standards. A common question we receive is, "What is 304 in SS 304?" This article clarifies the meaning of "304" in the context of SS 304, detailing its significance as a grade designation, properties, and applications for uses like plat stainless 304 and SA 240 GR 304 pipe. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA 240 stainless steel plate offerings.

What is 304 in SS 304?

In SS 304, the "304" refers to a specific grade of austenitic stainless steel as defined by standards like AISI (American Iron and Steel Institute), ASME SA 240, and ASTM A240. The "SS" stands for stainless steel, indicating that 304 is a type of corrosion-resistant steel alloy containing at least 10.5% chromium. Specifically, 304 is a chromium-nickel austenitic stainless steel grade (UNS S30400, EN 1.4301) known for its excellent corrosion resistance, formability, and non-magnetic properties in the annealed state, often referred to as SA 240 304 non magnetic. The 304 designation originates from the AISI numbering system, where it identifies the alloy’s composition and properties, making it suitable for applications like plat stainless 304, SA 240 GR 304 pipe, and food processing equipment.

Significance of "304"

• Historical Context: The 304 grade was established by AISI to denote a specific composition within the 300-series stainless steels, characterized by ~18% chromium and ~8% nickel.
• Standards: It aligns with ASME SA 240 GR 304 (for pressure vessels) and ASTM A240 304 (general applications), as well as international equivalents like SUS304 (JIS) and 06Cr19Ni10 (GB).
• Properties: The 304 designation ensures a balance of corrosion resistance, strength, and workability, distinguishing it from other grades like 316 (molybdenum-enhanced) or 201 (low-nickel).

Gangsteel’s sa 240 gr 304 plates meet these standards.

Chemical Composition of SS 304

The chemical composition of SS 304, as specified by ASME SA 240 and ASTM A240, defines the "304" grade:

• Chromium: Forms a passive oxide layer for corrosion resistance.
• Nickel: Ensures austenitic structure and SA 240 304 non magnetic properties.
• Carbon: Limited to ≤0.08% for weldability, though SS 304L (≤0.03%) is preferred for critical welds. See sa 240 gr 304l.

For detailed specs, refer to our SS 304 data sheet.

Mechanical Properties of SS 304

The mechanical properties of SS 304 (annealed, 8-75 mm thick) support its versatility:

Cold-working can increase tensile strength (up to 900 MPa) but reduces ductility.

Physical Properties

• Density: 8.00 g/cm³, ideal for lightweight designs (e.g., a 1m x 1m x 3mm plate weighs ~24 kg).
• Melting Point: ~1400-1450°C.
• Thermal Conductivity: 16.2 W/m·K.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K.
• Electrical Resistivity: 0.72 × 10⁻⁶ Ω·m.

These properties make SS 304 suitable for plat SS 304 3mm and plate 2 mm SUS 304.

Corrosion Resistance and Weldability

SS 304 offers excellent corrosion resistance in:

• Atmospheric conditions, freshwater, and mild acids (food-grade).
• General environments, outperforming SS204 vs SS 304 due to higher nickel content.

It’s less resistant to chloride pitting compared to SS 316L. Weldability is good with ER308 fillers, but SS 304L is preferred for critical welds. For chloride-heavy environments, explore sa 240 gr 316l.

Applications of SS 304

SS 304 is used in:

• Food Processing: Tanks, conveyors, and equipment (hygienic, non-tarnishing).
• Chemical Industry: Vessels and SA 240 GR 304 pipe for mild corrosives.
• Architecture: Structural panels like plat stainless 304.
• Automotive: Components requiring corrosion resistance.
• Medical Devices: Non-magnetic instruments leveraging SA 240 304 non magnetic properties.

For high-temperature applications, explore sa 240 gr 304h or sa 240 gr 321.

Pricing and Availability

As of October 15, 2025, SS 304 plate prices (2B finish, 3-6mm) range from $1.55-$3.50/kg globally. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa 240 gr 304 plates, including sizes like plate 2 mm SUS 304.

Why Choose Gangsteel?

Gangsteel provides certified SS 304 plates with competitive SS 304 plate price and sizes like plat stainless 304. Our 600+ ton inventory supports global delivery. For quotes or to learn more about SS 304, visit our astm a 240 stainless plate page or email admin@gangsteel.com.