Technical Characteristics Of Hot Rolling Mills

I. Advantages of Process Characteristics
High-temperature processing characteristics: Hot rolling mills roll at temperatures above the recrystallization temperature of metals (typically 1200℃-1300℃), endowing steel with better plastic deformation capacity. Compared with the cold rolling process, it can reduce processing energy consumption by 15% to 20%, and is particularly suitable for processing with large deformation.
The production efficiency is outstanding. It adopts a continuous rolling production line design. The speed of the modern hot continuous rolling mill can reach 25m/s, and the annual production capacity of a single production line exceeds 5 million tons. A typical six-stand finishing mill group can complete the entire rolling process in just 90 to 120 seconds.
The material has wide adaptability and can process slabs with a thickness of 150-300mm. The finished product thickness can be flexibly adjusted within the range of 1.2-25.4mm. It can not only produce common carbon steel, but also roll special alloy materials such as stainless steel and silicon steel.
Ii. Structural Features of the Equipment
The diameter of the working rolls configured for heavy equipment usually reaches 800-1400mm, and the designed value of the rolling force is 20-50MN. It adopts a four-roll or six-roll structure and is equipped with a hydraulic AGC automatic thickness control system, with a thickness tolerance that can be controlled within ±0.05mm.
The temperature control system is equipped with segmented heating furnaces (preheating section, heating section, and homogenization section), and adopts intelligent combustion control technology, with the temperature difference controlled within ±10℃. Laminar flow cooling devices are configured during the rolling process, and the cooling rate adjustment range is 5-30℃/s.
The highly automated integrated PLC control system realizes closed-loop control of parameters such as rolling speed, roll gap and tension. The latest model is equipped with a digital twin system, which can simulate the rolling process in real time for process optimization.
Iii. Product Performance Characteristics
Microstructure characteristics: The hot-rolled state product has a typical hot-rolled banded structure, with grain sizes ranging from 20 to 50μm. Fine grain strengthening effect can be achieved through controlled rolling and controlled cooling technology, with the yield strength increased by 10%-15%.
The surface quality performance was achieved by using a high-pressure water descaling system (with a pressure of 18-22 mpa), and the removal rate of iron oxide scale was over 98%. The surface roughness of the conventional products is Ra3.2-12.5μm, meeting the requirements of most industrial applications.
Residual stress distribution: The residual stress in hot-rolled sheet and strip shows a characteristic distribution of surface compressive stress and core tensile stress. The stress value is usually 1/3-1/2 of that of cold-rolled products, which is more conducive to subsequent processing and forming.