It consists of Q+ number + quality grade symbol + deoxidation method symbol. Its steel number is preceded by "Q", which represents the yield point of the steel, followed by a number indicating the yield point in MPa. For example, Q235 represents a carbon structural steel with yield point (σs) of 235 MPa. ② If necessary, the steel number can be marked after the quality grade and deoxidation method symbol. The quality grade symbols are A, B, C and D respectively. Symbol of deoxidation method :F stands for boiling steel; b stands for semi-killed steel; Z stands for dead steel; TZ stands for special sedative steel. Sedative steel may not be marked, that is, Z and TZ may not be marked. For example, Q235-AF indicates grade A boiling steel. Hot rolling is a mill process which involves rolling the steel at a high temperature (typically at a temperature over 1700° F), which is above the steel’s recrystallization temperature. When Mild Steel Sheet Metal is above the recrystalli…