Making of hot-rolled steel plates - 1

It is interesting to note how steel sheets are being made. As the name implied, the steel plate is rolled to its desired thickness while the steel slab is heated to red hot temperature. The equipment that is used to roll the steel slabs is called a mill stand which consists mainly of work rollers, top and bottom; usually the top roller could be screwed downward or mechanically gear-driven to decrease the gap or distance between the two rollers to achieve the thickness by stages. The downward movement of the top roller or screw down is, at a progression of 7-8mm and subsequently when near to the desired thickness, the decrease is more gradual, say 5mm or less.


To start with, slabs of various thickness dimensions are procured in, cut to the sizes which fit the inside dimensions of the furnace, and the slabs are raised to temperature in the region of 1250 degree C. And the heated slab is then discharged onto a conveyor of rollers, and these rollers will carry the heated slab to a primary descaling station, whereby high pressure water jet in the region of 120 bars are sprayed onto both the top and bottom surfaces of the slab. The force and the cooling will crack and peel the scales of the oxidized layers of the slabs.

The descaled slab is normally subjected to a secondary descaling process where water is blasted against the surfaces to get rid of the remaining scales. Then the work rollers will start to roll the slab back and forth until the desired thickness and length is achieved and then pass on to another station called the hot leveler.

The hot leveler is an assembly of rollers that flattens the surface of the plates so as to meet the industry standard requirement. Without going through the hot leveler process, the surface of the plate is wavy and uneven.

After this leveling process, the steel plates are then sheared or cut to standard sizes for delivery to customers.

This is a simple layman description on the hot rolled steel plates processes. Of course running a steel mill is more complicated than this. If there is chance I will go into the technical details of it.