Stainless steel is one of the most widely used materials in modern manufacturing and daily life, prized for its corrosion resistance, durability, and versatility. Among the many grades available, 304 SUS stainless steel stands out as one of the most common and reliable choices across industries. From household appliances and automotive parts to architectural elements and medical equipment, this stainless steel grade offers a balance of mechanical strength, formability, and cost-effectiveness that makes it highly sought after by engineers, designers, and manufacturers alike.

Despite its popularity, there is often confusion between the terms SUS304 and SS304. Understanding their properties, differences, and ideal applications is critical for anyone involved in material selection or product design. This article provides a comprehensive overview of 304 SUS stainless steel, highlighting its characteristics, advantages, limitations, and uses.

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What Is 304 SUS Stainless Steel?

304 stainless steel is an austenitic stainless steel alloy, primarily composed of approximately 18% chromium and 8% nickel, with small amounts of carbon, manganese, and silicon. These elements provide a balance of corrosion resistance, mechanical strength, and ease of fabrication.

The term SUS304 comes from the Japanese Industrial Standards (JIS), where “SUS” stands for “Steel Use Stainless.” On the other hand, SS304 or 304 stainless steel is commonly used in international standards, such as ASTM or AISI. Despite the different naming conventions, both terms refer to the same material with nearly identical chemical composition and mechanical properties.

Typical mechanical properties of 304 stainless steel include a tensile strength of approximately 515–750 MPa, yield strength of at least 205 MPa, and elongation of 40% or more. Its hardness is moderate in the annealed condition, providing sufficient strength while allowing formability and weldability.

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Key Properties of 304 SUS Stainless Steel

Corrosion Resistance
One of the defining features of 304 stainless steel is its ability to resist corrosion in a wide range of environments, including air, water, and many common chemicals. The chromium content forms a passive oxide layer on the surface, preventing rust and oxidation.

Mechanical Strength and Toughness
304 stainless steel provides a combination of strength and toughness suitable for many structural and functional applications. Its mechanical properties allow it to withstand moderate loads without deformation, making it reliable for long-term use.

Formability and Weldability
The alloy is easy to fabricate through processes such as bending, stamping, deep drawing, and welding. This makes it suitable for producing complex components with minimal machining.

Temperature Stability
The material maintains stable performance at both low and moderately high temperatures, ensuring consistent functionality across various applications.

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Differences Between SUS304 and SS304

The primary difference between SUS304 and SS304 lies in naming standards rather than material performance. SUS304 follows the JIS standard, commonly used in Japan and parts of Asia, while SS304 conforms to ASTM or AISI standards, widely used internationally.

In practice, the two can be considered interchangeable, provided that material certification (MTC) and compliance with the relevant standard are verified. For international projects or export-oriented manufacturing, specifying the standard is essential to ensure supply chain reliability and regulatory compliance.

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Advantages of 304 SUS Stainless Steel

Versatility
304 stainless steel is suitable for a wide range of applications, from automotive and industrial components to home appliances, kitchen equipment, and architectural structures.

Durability
Its resistance to corrosion, oxidation, and wear ensures long-lasting performance, even in frequently used or exposed environments.

Ease of Fabrication
The alloy’s good formability and weldability reduce manufacturing complexity and allow for efficient production of complex shapes.

Cost-Effectiveness
Compared to higher-grade stainless steels or specialty alloys, 304 offers an excellent balance between performance and cost, making it a practical choice for mass production.

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Limitations of 304 SUS Stainless Steel

While 304 stainless steel is highly versatile, it is not suitable for all conditions:

• High Chloride or Marine Environments: Exposure to seawater or strong chlorides can lead to corrosion over time. In such cases, higher-grade alloys like 316 stainless steel may be more appropriate.

• Extreme Loads or Temperatures: For applications requiring very high strength, fatigue resistance, or elevated temperature performance, 304 may not suffice.

• Surface Maintenance: Although corrosion-resistant, the passive oxide layer can be compromised by scratches, contaminants, or harsh chemicals. Regular cleaning and maintenance are recommended.

• Standard Compliance: Differences between JIS and ASTM standards may affect international procurement. Ensure that material certificates and compliance documents match the intended standard.

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Applications of 304 SUS Stainless Steel

304 SUS stainless steel’s combination of corrosion resistance, strength, and formability makes it suitable for a wide array of industries:

Automotive
Used in exhaust systems, structural brackets, seat frames, and other components requiring durability and corrosion resistance.

Home Appliances
Common in kitchen sinks, ovens, refrigerators, washing machines, and other appliances, providing both structural integrity and aesthetic appeal.

Construction and Architecture
Ideal for railings, door frames, cladding, and decorative panels due to its clean finish and resistance to environmental exposure.

Medical and Food Industry
Applied in surgical instruments, food processing equipment, piping, and tanks where hygiene and corrosion resistance are critical.

Industrial Equipment
Found in pumps, valves, chemical tanks, and machinery parts, ensuring reliability and durability in manufacturing environments.

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Choosing 304 SUS Stainless Steel vs. Other Grades

When selecting stainless steel, consider the application requirements:

• 304 vs. 316: 316 offers superior corrosion resistance, especially in marine or chemical environments.

• 304 vs. 430: 430 is ferritic, less corrosion-resistant, and less ductile but often cheaper.

• 304 vs. 201: 201 is a lower-cost alternative with reduced nickel content, suitable for decorative or light-duty applications.

Choosing the right grade involves balancing corrosion resistance, mechanical strength, cost, and manufacturability.

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Conclusion

304 SUS stainless steel is one of the most versatile and widely used stainless steel grades worldwide. Whether referred to as SUS304 or SS304, the material provides excellent corrosion resistance, mechanical strength, formability, and cost efficiency. Its suitability across industries—from automotive and appliances to architecture and medical equipment—demonstrates its unmatched adaptability.

While 304 stainless steel is highly reliable for many applications, engineers and designers must consider environmental conditions, load requirements, and international standards to ensure optimal performance. By understanding its properties, advantages, limitations, and differences from other grades, manufacturers can make informed decisions and deliver durable, high-quality products that meet global expectations.