Q235B, SS400, A36 and S235JR are the same family of general structural carbon steel specified under four different national standards. Buyers meet all four because projects are designed to different codes.

The four systems

• Q235B: Chinese GB/T 700, 235 MPa minimum yield, B quality 20 deg C impact.
• SS400: Japanese JIS G3101, 400-510 MPa tensile, no specified yield by grade.
• A36: American ASTM A36, 250 MPa minimum yield (36 ksi).
• S235JR: European EN 10025-2, 235 MPa yield, JR quality +20 deg C impact.

Are they interchangeable?

For general construction and fabrication, yes in practice: chemistry and strength overlap closely and mill certificates document what was actually supplied. For pressure equipment, bridges or code-stamped work, substitution needs the designer's approval because impact testing and traceability rules differ.

How to order

Name the grade and standard your drawings call for, and add thickness, size and quantity. We supply carbon steel plate from 3 to 200 mm, cut to size, with EN 10204 3.1 mill test certificates and third-party inspection on request.

Related reading

• Hot Rolled vs Cold Rolled Steel: A Buyer's Guide
• Carbon Steel vs Stainless Steel: How to Choose
• Stainless Steel Grades Explained: 201, 304, 316L, 430