Are you familiar with low-temperature rolling?

Low-temperature rolling involves heating steel billets to temperatures lower than conventional heating levels, followed by rolling performed at these reduced temperatures—more precisely referred to as medium-temperature rolling. The primary goal is to significantly cut down on fuel consumption required for billet heating and minimize metal burn-off during the process.

Old-style rolling mills operate at low speeds, leading to significant temperature drops in the workpiece during the rolling process. This is why the initial rolling temperature had to be set very high. In contrast, modern continuous rolling mills achieve much higher speeds, and the deformation heat generated within the workpiece during rolling helps maintain its temperature—at least preventing it from dropping—and even causes a slight increase. This makes low-temperature rolling possible under today’s conditions.
Low-temperature rolling refers to the process of rolling metal at temperatures lower than those typically used in conventional hot rolling. Not only does low-temperature rolling reduce energy consumption and minimize metal burn-off, but it also enhances product quality, leading to significant economic benefits.

There are generally two types of low-temperature rolling procedures for steel bars. One approach leverages the minimal temperature drop or even slight temperature rise that occurs during continuous rolling, allowing operators to reduce the initial rolling temperature—from 1000–1100°C down to 850–950°C—while keeping the final rolling temperature relatively close to the initial level. This method requires strengthening the rolling mill by increasing motor power and boosting energy consumption during the process. However, because the heating temperature is lowered, fuel usage is reduced, ultimately resulting in an overall energy-saving benefit of about 20% when factoring in both the increased efficiency and lower fuel costs.

Another approach not only lowers the initial rolling temperature but also leverages the cooling sections between stands to reduce the final rolling temperature below the recrystallization temperature (700–800°C). Combined with a deformation level of 40%–50%, this process effectively completes a thermo-mechanical treatment, refining grain size, achieving uniform microstructure, and enhancing both the mechanical and weldability properties of the steel—while also improving the surface quality of the rolled product. Notably, this method outperforms any conventional heat-treatment technique. As a result, modern rolling mills often increase the distance between stands, with some even incorporating large side guide rolls or adding intermediate cooling water tanks. Low-temperature rolling offers precise control over grain size. However, a key limitation of implementing low-temperature rolling is that the mill equipment and its main drive motors are typically designed based on traditional parameters, which often leads to insufficient capacity to support this advanced process.

Low-temperature rolling refers to the process of rolling metal at temperatures lower than those typically used in conventional hot rolling; it is also known internationally as medium-temperature or warm rolling. The primary goal is to significantly reduce fuel consumption required for heating the billets, thereby minimizing metal burn-off during the process. According to international reports, a typical wire and bar mill consumes about 650 kWh/t of energy, with roughly 520 kWh/t dedicated to heating the billets to 1150°C—leaving only 110 kWh/t available for the actual rolling operation. Production trials conducted at Sweden’s Fagersta plant demonstrated that rolling a 70 mm medium-carbon steel billet (SSl650) through 14 passes to produce a 10.5 mm square bar with sharp corners consumed approximately 182 kWh/t less energy when performed at 750°C compared to rolling at the conventional temperature of 1150°C. Importantly, this method avoided issues such as poor bite and surface defects. Moreover, when applying low-temperature rolling to alloy steels like spring steel, bearing steel, tool steel, and stainless steel, the process proved viable within a temperature range of 800–950°C, resulting in energy savings of 85 to 130 kWh/t.