ASTM A36 vs Q235B: revealing the main differences

A36 is similar to Q235B, but there are differences between A36 and Q235B as follows:

1. Different yield strengths (A36 = 250MPa, Q235B = 235MPa);

2. Different tensile strengths (A36 = 400-550MPa, Q235B = 375-500MPa);

3. Different requirements for element content: (A36: C≤0.25%, Si≤0.4%, P≤0.04%, S≤0.05%; Q235B: C=0.12-0 .2%, Si≤0.3, P≤0.045%, S ≤0.045%).

Q235 has requirements for manganese content (Mn = 0.30-0.70%), while A36 has no requirements for manganese content.

If we only compare the mechanical properties of the materials, A36 is considered to have similar mechanical properties to 20# high-quality carbon structural steel. The tensile strength of 20# steel is not less than 410 and the yield strength is not less than 245, which is similar to the mechanical properties of A36.

Comparison of A36, SS400 and Q235

1. Different standardization organizations:

A36 is a material standard of the American Society of Mechanical Engineers (equivalent to ASTM specifications), SS400 is a material standard of Japanese Industrial Standards (JIS G3101), and Q235 is a material standard of Chinese National Standards (GB700).

2. Different chemical compositions:

Chemical composition comparison table for A36, SS400 and Q235:

In A36, the Mn element content is not used due to the different plate thicknesses (or round diameters of the steel). For thicknesses less than 20mm, Mn is not included. Q235 has requirements for the content of C, Si, Mn, S, P, while SS400 only requires S and P to be less than 0.050, with no other requirements.

3. Different mechanical properties of materials:

The tensile strength of A36 is 58-80 Ksi (approximately 400-550 MPa) and the yield strength is 36 Ksi (approximately 250 MPa);

The tensile strength of Q235 is 370-500 MPa and the yield strength is 235 MPa;

The tensile strength of SS400 is 400-510 MPa and the yield strength is 245 MPa.

(The mechanical properties of SS400 and Q235 are provided as examples for steel plate thicknesses less than 16 mm.)

From the above data, it can be seen that the material names of ASME A36 and Chinese Q235 are based on the yield strength of the material, while SS400 is named based on the tensile strength of the material. From the analysis of the mechanical properties of the material, A36 is equivalent to SS400, while Q235 is slightly inferior in terms of material properties.

4. Replacement of A36, SS400 and Q235:

Although Q235 has slightly lower mechanical properties compared with A36 and SS400, in practical operations, as long as the owner does not explicitly require it, these three materials can often be used interchangeably.

If we only compare the mechanical properties of the materials, I believe that A36 and SS400 have similar mechanical properties to 20# high-quality carbon structural steel. The tensile strength of 20# steel is not less than 410 and the yield strength is not less than 245, which is similar to the mechanical properties of A36 and SS400.