Q represents the yield of this material, 345 refers to the yield value of this material, in the 345 or so. As the material thickness will increase its yield value decreases. Similar to the naming method in Q235.
Q345A, Q345B, Q345C, Q345D, Q345E. This is a class distinction represents mainly the impact of different temperature and Q345A level, is not to shock; Q345B grade, is 20 degrees room temperature impact; Q345C level, is 0 degree impact; Q345D level, is -20 degree of red; Q345E level is -40 degrees impact. The impact of different temperatures, the impact of values ??are different. In the plate, the case of low-alloy series. In the low alloy material, such material is the most common.