Influence of Concentration of Sodium Metasilicate and Descaling on the High Temperature Lubricating Effects Evaluated by Hot Rolling Mill

Lubricant is vital to improve energy efficiency and workpiece durability for the moving counterpart. High-temperature lubricants are important for the hot rolling process to reduce the rolling force and protect the roller and the strips. The current paper concerns eco-friendly sodium metasilicate as a high-temperature lubricant. A hot rolling mill is employed to evaluate the lubrication effect of sodium metasilicate. The influence of crucial factors of concentration of lubricant and descaling is discussed; the rolled surface was analyzed by scanning electron microscopy, energy dispersive spectroscopy, and 3D profilometer. The results depict that the sodium metasilicate can reduce the rolling force by about 7.8% when the concentration of sodium metasilicate is 18% and above, and descaling of the hot stripe makes the lubrication effect more effective, which can reach a 12.7% reduction in the rolling force. This lubrication is attributed to the formed melts of the sodium silicate layer that offers an easy shearing interface. For the un-descaled samples, the lubricant will be compacted and mixed with the oxide scale, and weakens the lubrication effect. This work suggests that sodium metasilicate can be a high-temperature lubricant for hot rolling; descaling is vital, not only for the quality of the product but also for the efficiency of the lubricant. This work will also be useful for the concentration selection of glass lubricant.