◆ Mechanical polishing:

This method is usually done manually, which is to smooth out the concave and convex position of the steel coil. In this process, props such as sandpaper and oil stone strips are used. By mechanically polishing the steel coil, the surface quality of the steel coil can be improved.

◆ Chemical polishing:

A chemical reaction is used in this polishing method to flatten the raised position of the steel coil plate. The biggest advantage is that there is no need to use too complicated equipment in this process and the polishing effect is good.

◆ Electrolytic polishing:

The principle of electrolytic polishing is very similar to chemical polishing, but the effect of electrolytic polishing is better because this polishing method uses electrolyte to flatten the raised position on the surface of the steel coil.

Hot rolled steel coil:

With continuous casting slab or primary rolling slab as raw material, it is heated by step heating furnace and enters into rough rolling mill after high pressure water phosphorus removal. Rough rolled material enters the finishing mill through head cutting, tail cutting and computer controlled rolling: after finishing, it is cooled by laminar flow (computer controlled cooling speed) and coiled into straight hair rolls by coiling machine.

Cold rolled coil:

With hot rolled steel coil as raw material, cold continuous rolling after pickling to remove oxidation skin. The finished product is rolled hard coil. Continuous cold deformation caused by cold work hardening so that the strength and hardness of the rolled hard volume increased, toughness and plasticity indicators reduced, so that the stamping performance becomes poor. It can only be used for simply deformed parts. Since hot-dip galvanizing units are equipped with annealing lines, hard rolled coils can be used as raw material for hot-dip galvanizing plants.

There are three main differences between cold rolled coil and hot rolled coil:

◆ In appearance, the color of cold hard coil is a little darker.
◆ In terms of surface quality, structure and dimensional accuracy, cold hard rolled coil is better than cold rolled plate.
◆ In terms of performance, the cold hard coil directly obtained from hot rolled coil through cold rolling process, process hardening occurs during the cold rolling process, so that the yield strength and internal stress residual part increases, and it looks “hard” from the outside, so it is called cold hard coil. Generally speaking, the default delivery condition of cold rolled coil is annealed. Nowadays, most steel is sold in coils. After a company purchases a coil, it needs to be uncoiled before it can be processed. Generally speaking, it is used more in the automotive industry. Of course, many automotive industries outsource the uncoiling process and the plants use the uncoiled sheets directly.

Advantages of cold rolled steel coils.
Fast forming speed, high yield, no damage to the coating. Can be made into a variety of cross-sectional forms to meet the needs of the conditions of use; cold rolling can make the steel produce a large plastic deformation, thereby increasing the yield point of steel.

◆ The reasonable accumulation of carbon steel coil is the basis of safe transportation

The loading and unloading of carbon steel coil should be stacked at the bottom of the cargo hold, with one side of the cargo hold arranged on the other side and stacked layer by layer. carbon steel coil axis should be in line with the ship’s bow line, side by side and close together. Generally, the coil steel can be stacked in three layers, depending on the strength of the cabin floor. According to the calculation of the total load and the local load of the bilge area, no overload accumulation is allowed.

◆ Laying rolled steel liner is an important part of safe transportation

Study the binding scheme carefully before loading the rolled steel. At present, the anti-slip device in each port cannot disperse the pressure but has anti-slip effect. carbon steel coil should be planked on the ship bottom and bulkheads on both sides, and carbon steel coil should be stacked on transverse anti-slip liner planks, at least 2 of them. Angles should also be placed on the bottom to prevent rolling. Both wings of the first roll of steel in each row shall be solid. After unloading, each bulkhead should be placed close to at least 2 triangular wood liners. After loading, more boards and corners need to be prepared for backup.

◆ How to arrange coils is necessary for safe transportation

The carbon steel coil loaded on each ship often vary in size. When loading, small coils of steel should be considered to be arranged in the hatch as far as possible, large coils of steel should be arranged outside the hatch as far as possible, and a row of coils of the same volume should be chosen; when the conditions do not allow, large coils of steel are best loaded on both sides of the cargo hold, and small coils of steel are loaded in the middle of the cargo hold, but the working surface must be neatly arranged to facilitate the operation of the next row.

◆ Reasonable bundling of carbon steel coil is the key to safe transportation

Carbon steel coil bundling should be followed up in time, and bundling should be done one row at a time in sequence.
① Each steel strip should be tightened at the nearest distance from the adjacent coil to prevent loosening.
② the bundling of steel coils at both ends of the whole row.
③ the outermost row of the upper and lower steel coil bundle, the channel is appropriately increased.
④If the carbon steel coil is installed to three layers high, the bottom layer can be untied.
⑤ If for some reason there is no binding position, you can ask to install a backpack or connect the front and rear rows and connect three rows.
If there is a steel belt tensioner on board, some steel belts need to be reserved after loading to strengthen the loose coil steel when sailing.