Q235 ordinary carbon structural steel, Q stands for yield strength, 235 means yield strength of 235 MPa, so what do Q235A and B mean?

The carbon content of q235a is 0.14-0.22%, and the carbon content of q235 is 0.12-0.20%. The values of a and b are graded, mainly because of the different impact temperatures. A means no impact and b means impact at room temperature of 20 degrees. The mechanical properties of steel made of Q235B are far superior to those made of Q235A.

Such as: angle steel, channel steel, I-beam, H-beam and other steel products, the steel factory has marked them on the identification plate before the finished profiles leave the factory.

If only q235 is marked, it is not correct, just choose the required material according to the impact resistance.

Some engineers said that Q235 cannot be heat-treated, which is wrong. Q235 is a low-carbon steel that can be heat-treated, but the hardness of the heat treatment is not large, and the effect is not good, and you need to pay attention to problems such as deformation and cracking. 

The advantage of q235 is that the price is relatively cheap, and because it is low-carbon steel, it is generally used for welding parts, etc., and its welding performance is good. Good processing performance. The disadvantage is that it is easy to rust and not resistant to corrosion. Generally, surface treatment such as baking paint and powder spraying will be carried out.