Hot rolling and cold drawing

Hot rolling is relative to cold rolling. Cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature. To put it simply, hot rolling is to heat a piece of steel billet to a certain temperature, then roll it through several passes, then trim and straighten it into a steel plate.

The difference between hot rolling and cold rolling:

1. The forming processes of hot-rolled steel plates and cold-drawn steel plates or steel plates are the same. They have a great influence on the microstructure and mechanical properties of steel. Hot-rolled steel plates are mainly used, while cold-rolled steel plates are only used to produce small and Thin seamless steel pipe.

2. Cold-formed steel sections are allowed to undergo local buckling, which can fully utilize the load-bearing capacity of the rods after buckling; while hot-rolled steel sections are not allowed to undergo local buckling.

3. Since the causes of residual stress of hot-rolled steel plates and cold-rolled steel plates are different, the distribution of their cross-sections is also very different. The residual stress distribution on the cold-formed steel section is curved, while the residual stress distribution on the hot-rolled steel or welded steel section is membrane-shaped.

4. The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional performance of hot-rolled steel is better than that of cold-rolled steel.

5. Hot rolling process: pipe making - heating - hot punch - rolling - cooling bed, cold drawing process: initial processing - drilling - pickling - phosphating - drawing - annealing.