Do you know the difference of ASTM-A36, Q235B, and SS400?

There is almost no difference among ASTM-A36, Q235B, and SS400 On the surface, and they have many similarities in chemical composition and mechanical properties. They can even be used interchangeably to some extent. So, what are the differences of them? Today, let's analyze them together.

1. In terms of executive standards
The executive standards of the three materials are different. A36 is a carbon structural plate under the standard of American Society for Testing Materials (ASTM) , SS400 is a material of Japanese Industrial Standard (JIS) G3101 (rolled steel of general structures), and Q235B is made according to the Chinese standard GB/T700.

2.In terms of chemical composition

Steel Standard	Steel Grade	Chemical Composition
Steel Standard	Steel Grade	C(≤)	Mn(≤)	Si(≤)	S(≤)	P(≤)	Cu(≤)
ASTM	A36	0.26	-	0.40	0.050	0.040	0.2min
GB	Q235B	0.12~0.20	0.30~0.70	0.30	0.045	0.045	GB
JIS	SS400	-	-		0.050	0.050

The content of Mn element in A36 varies depends on the thickness (or diameter) of the plate (below 20mm without Mn). Q235 has requirements for the content of elements such as C, Si, Mn, S, P, etc. SS400 has no other requirements, and the content of S and P are less than 0.050.

3.In terms of physical property

The tensile strength of A36 is 400-550MPa, and the yield strength is 250MPa; The tensile strength of Q235 is 370-500 MPa, and the yield strength is 235 MPa（thickness ＜ 16 mm）; The tensile strength of SS400 is 400-510 MPa, and the yield strength is 245 MPa（thickness ＜ 16 mm）.

It can be found that A36 and Q235 are named after the yield strength of the material, while SS400 is named after the tensile strength. In this term, SS400 is more similar to A36.

Do you have a clearer judgment on ASTM-A36, Q235B, and SS400 now? Based on the above content, we can better choose a suitable product with actual requirements and application standards.