How to distinguish Q235 steel and Q345 steel?

The appearance of Q235 steel and Q345 steel are almost the same. The color difference has nothing to do with the material of the steel, but is caused by the different cooling method after the steel is rolled. Under normal circumstances, the surface of the steel plate after natural cooling is red. If a rapid cooling method is used, a dense oxide layer is formed on the surface, which will appear black.

Q345 steel is used for general strength design, because Q345 steel has higher strength than Q235 steel. It is better to use Q235 steel when designing with stability control.

So, how to distinguish Q235 steel and Q345 steel?

1. Q235 steel and Q345 steel can be distinguished according to the color of the steel plate. For the steel that has just entered the site, the color of Q235 steel is blue, and Q345 steel is a little red.

2. The most distinguishable test is chemical analysis. Q235 steel and Q345 steel have different carbon content and different chemical content.

3. Distinguish by welding method: two steel plates of unknown material are jointed and welded with ordinary welding rods. If the steel plate with cracks appears, it is proved to be Q345 steel.

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