The roll material for small-sized steel and bar rolling mills is an important factor determining the quality and performance of the rolled products. Selection of the right roll material has a direct influence on the lifetime and quality of the final product.
Rolls are the most important component or consumable of the steel bar rolling mill. So rolls’ quality affects the production yield and efficiency of the mill. The rolls used in the steel rolling mill are typically wider than the steel bars being rolled and they must be able to endure and withstand the wear, temperature, and deformation placed on them by the processes of forming, sizing and finishing.
Rolling Mill rolls must have high wear resistance and strength so that the steel being rolled does not break, crack or deform and wear quickly. To obtain this capacity, the material used to make the roll must be strong enough to withstand these operations but also hard enough to maintain its shape in the milling process. Roll selection is critical for steel quality and productivity of the mill.
Rolls used in the most common rolling processes are made of special cast iron, cast steel and forged steel. There are also composite rolls, made from more than one type of material. For example, many lightweight calibers rolls for low-speed rolling mills are made with a carbon steel core which is itself reinforced by a layer of middle chromium steel and floor or sintered layer of powdered cast iron.
In particular, the rolls used in steel bar rolling mills are usually made of special cast iron or cast steel. Cast iron rolls (white cast iron, spheroidal graphite cast iron and pearlitic nodular cast iron) are mainly used for mild steel and low-carbon steel bars and special alloyed steels.
Cast steel rolls (chrome molybdenum steel, chromed steel and high-speed steel) are widely employed for rolling low alloyed, medium-carbon and high-carbon steel bars, rods and wire products. The use of high-speed steel is limited to rolling mill speeds of up to 25 m/s.
The selection of the right roll material depends on the product that the rolling mill is producing, the desired yield and quality of the material being rolled and the rolling speed, temperature and load of the mill. Furthermore, the level of automation and maintenance of the mill must also be taken into consideration in order to select the right roll material.
Forged steel and composite rolls are becoming increasingly popular with rolling mills. Forged steel rolls are suitable for rolling higher strength materials. Meanwhile, composite rolls are becoming more widely used due to their better wear resistance, cracking resistance and capacity for producing complex shapes than conventional rolls.
Whichever roll material is chosen, it must be correctly installed and correctly lubricated in order to ensure maximum mill performance. The correct roll material selection is an important factor in producing quality products. By making an informed selection, the performance, yield and maintenance of the mill can be improved.
