In the process of steel rolling (mainly cold rolling), in order to reduce the friction between the rolling mill and the rolled material, lower the rolling force and power consumption, make the rolled material easy to extend, control the rolling temperature, and improve the quality of the rolled product, it is necessary to add lubricating coolant between the rolling mill and the rolling material contact surface. This process is called steel rolling process lubrication.  
Cold rolling is usually achieved by using hot roughing and finishing to obtain steel coils with a thickness of 2-4mm, which have undergone acid washing and annealing treatment as billets, and then rolling them into thin plates with a thickness of 0.8mm to 0.01mm using a multi roll rolling mill (reversible or continuous rolling). Due to the high deformation resistance of cold metals, the rolling force of modern cold rolling mills has reached thousands of tons, and the rolling speed is close to 2500m/min. Obviously, during the high-speed deformation process of metals, on the one hand, a large amount of thermal energy is inevitably generated due to the friction between molecules inside the metal; On the other hand, the thinning (extension) of the rolled material inevitably causes relative motion between the rolling mill and the surface of the rolled material.  
The basic requirements for lubricants in cold rolling process are:
1. Appropriate oiliness, that is, it can still form a boundary oil film under extreme rolling pressure to reduce friction resistance and metal deformation resistance; Reduce the wear of rollers and extend their service life; Increase the amount of compression, reduce the number of rolling passes, and save energy consumption. However, it is necessary to consider that there must be a certain amount of friction between the rolling mill and the steel periodically in order for the steel to bite into the rolling mill. If the friction coefficient is too low, it will slip. So the lubrication performance must be appropriate
2. Good cooling capacity, which can absorb the heat generated during the rolling process to the maximum extent, achieve constant temperature rolling, and maintain the stable roll shape of the rolling mill, so as to keep the thickness of the strip steel uniform;  
3. It has a good flushing and cleaning effect on the surface of the rolling mill and strip steel. To remove impurities and dirt mixed in from the outside and improve the surface quality of steel;  
4. Good physical and chemical stability. During the rolling process, it does not react chemically with the metal and does not affect the physical properties of the metal;  
5. Good annealing performance. In modern cold-rolled strip production, in order to simplify the process, improve labor productivity, and reduce costs, the production process of direct annealing without degreasing and cleaning is adopted when intermediate annealing is required. This requires that the lubricant does not undergo annealing corrosion due to its residue on the surface of the steel (i.e., producing spots on the surface of the steel);  
6. Good filtering performance. In order to improve the surface quality of steel, some rolling mills use high-precision filtering devices (such as diatomaceous earth) to remove impurities from the oil to the maximum extent possible. At this point, it is important to avoid the adsorption or filtration of additives in the oil to maintain its quality;  
7. Good oxidation stability and long service life;  
8. Good rust resistance. Short term storage between processes can have a good anti rust effect;  
9. It should not contain substances that harm human health or pungent odors;  
10. Wide range of oil sources, easy to obtain, and low cost.  
Hot rolling process lubrication
Improving the output of hot-rolled strip mills, reducing consumption, and increasing productivity are extremely important things in the steel rolling process. Practice in various countries has proven that the use of hot rolling oil can significantly reduce the wear of rolling rolls, lower power consumption, improve the surface quality of steel plates, and increase productivity.  
The following benefits can be obtained by using hot rolling (which has been proven in practice):
1. Improved the surface condition of the rolling mill.  
2. Reduced the unit consumption of rolling mills.  
3. Reduced energy consumption.  
4. Improved the surface quality of the strip steel.  
5. Reduce rolling pressure, making it easy to roll thin gauge strip steel.  
6. Promote research on hot rolling theory.