What is the difference about Japanese standard SS400 and National standard Q235B ?

SS400 is a marking method of Japanese steel materials and a judgment standard.

Structural steels in foreign standards are often classified according to tensile strength, such as SS400 (marked as such in Japan), where 400 represents σ The minimum value of b is 400MP. Ultra high strength steel refers to σ Steel not less than 1373 Mpa.

1. Different meanings
SS400: SS400 is a marking method of steel materials in Japan and a judgment standard, equivalent to Q235 steel in China.
Q235: Q235 ordinary carbon structural steel is also called A3 steel. Ordinary carbon structural steel plain plate is a kind of steel material.

2. Different yield points
The yield point of Q235 is greater than 235 MPa, while that of SS400 is 245 MPa.

3. Different standard numbers
The standard number of Q235 is GB/T700. The standard number of SS400 is JIS G3101.

4. Different strength
SS400: Structural steels in foreign standards are often classified according to tensile strength, such as SS400 (marked as such in Japan), in which 400 means σ the minimum value of b is 400MPa. Ultra-high strength steel refers to σ B Steel not less than 1373 Mpa.
Q235: Q represents the yield limit of this material. The following 235 refers to the yield value of this material, which is about 235MPa. The yield value will decrease with the increase of material thickness. Due to moderate carbon content, the comprehensive properties are good, and the strength, plasticity and welding properties are well matched.

5. Comparison of chemical composition between Q235 and SS400
Q235B carbon C: no more than 0.18
Q235B Mn: 0.35-0.80
Q235B silicon Si: no more than 0.3
Q235B sulfur S: no more than 0.04
Q235B phosphorus P: no more than 0.04
SS400 sulfur S: no more than 0.05
SS400 Phosphorus P: no more than 0.05

6. Comparison of mechanical properties between Q235 and SS400
Q235 yield strength: not less than 185.
Q235 tensile strength: 375-500
Q235 elongation: not less than 21
SS400 yield strength: no less than 215.
SS400 tensile strength: 400-510
SS400 elongation: not less than 17