Cold Hard coil is obtained by pickling and cold rolling the hot rolled coil. It is a kind of cold rolled coil.
Cold rolled coil (annealed state) : hot rolled coil through pickling, cold rolling, hood annealing, leveling, (finishing) ,can get Cold rolled coil.
The difference between Cold Rolled and Cold Hard :
1.From the appearance,cold Hard plate is a little Micro Black color generally
2.The surface quality ,Structure and Size precision of Cold Rolled is better than Cold Hard .
3.On the performance:
Since Cold Hard coil obtained directly by the cold rolling process ,in the cold rolling process is work hardened during cold rolling, the yield strength increases and some internal stress remains, and the external appearance is relatively hard, so it is called Cold Hard coil. .
Cold-rolled coil (annealed state): the cold hard coil is obtained by hood annealing before rolling. After annealing, the work hardening phenomenon and internal stress are eliminated (substantially reduced), that is, the yield strength is reduced to near cold. Before rolling.
Therefore, the yield strength: the cold hard coil is larger than the cold-rolled coil (annealed state), so that the cold-rolled coil (annealed state) is more favorable for stamping.
