ASTM 304 vs. SUS304: What’s the Difference?

Key Differences & Similarities

Standards: SUS304 is under Japanese JIS standards (JIS G 4304/4305), while SS304/304 is under American ASTM standards (ASTM A240).

Composition: Nearly identical 18% Chromium (Cr) and 8% Nickel (Ni) content, making them "18/8" steel.

Slight Range Difference: SUS304 might have a slightly higher Chromium range (18-20%) than ASTM 304 (17.5-19.5%), providing very stable corrosion resistance.

Properties: Both offer excellent corrosion resistance, weldability, formability, and mechanical strength, with any variations being minimal and dependent on specific manufacturing.

Application: SUS304 is common in Asian markets (Japan), while SS304 is prevalent in North America and Europe, making regional sourcing the primary deciding factor.

When to Choose Which

For Asian/Japanese Projects: Choose SUS304 to align with local standards and availability.

For US/European Projects: Choose SS304 (ASTM 304) for North American/European markets.

For Most Uses: Since properties are virtually interchangeable, your choice often depends on what's easily accessible in your region.