Commonly used hot-rolled steel
Hot-rolled steel, commonly used, refers to steel with defined cross-sectional shapes and sizes produced through a hot rolling process. It serves as a fundamental material in fields such as construction, machinery manufacturing, and bridge construction. Its cross-sectional shapes vary, including I-beams, channels, angles, H-beams, round bars, and square bars, each with unique mechanical properties and applications. Hot-rolled steel is made from billets and deformed through high-temperature rolling. It boasts high production efficiency, low cost, and optimal strength, meeting the load-bearing requirements of most structural components and making it an indispensable material in modern industry.
From a production perspective, the manufacturing of commonly used hot-rolled steel sections primarily involves billet heating, rolling, cooling, and finishing. First, the billet is heated in a furnace to a temperature of 1000-1250°C to impart good plasticity to the steel, facilitating deformation during rolling. The heated billet then enters the rolling mill, where it is rolled through a series of horizontal and vertical rolls to gradually form the desired cross-sectional shape. The rolling process varies depending on the type of steel section. For example, H-beams are typically rolled on universal mills, which form the flanges and web in a single pass, ensuring precise cross-sectional dimensions. Angle steel, on the other hand, uses multiple rolling passes to gradually adjust the angle and leg length. After rolling, the section is cooled naturally or under controlled conditions on a cooling bed to avoid internal stresses caused by rapid cooling. Finally, finishing steps such as straightening, cutting, and flaw detection ensure the product’s dimensional accuracy and surface quality.
In terms of performance characteristics, the mechanical properties of commonly used hot-rolled steel sections are primarily determined by their material and rolling process. Generally speaking, low-carbon steel hot-rolled sections (such as Q235) exhibit good plasticity and toughness, with a tensile strength between 375-500 MPa, making them suitable for structural components subject to static loads. Medium-carbon steel and low-alloy steel hot-rolled sections (such as Q355) possess higher strength, with a tensile strength of 470-630 MPa, making them suitable for applications subject to dynamic or heavy loads. Furthermore, the cross-sectional design of hot-rolled steel sections ensures optimal load-bearing properties. For example, I-beams have a large moment of inertia and excellent bending resistance, making them commonly used in beams. Channel flanges have symmetrical flanges, facilitating connection and making them suitable for structures such as brackets and frames. Hot-rolled steel sections also come in a wide range of sizes and specifications to meet the design requirements of diverse projects.
Hot-rolled steel is commonly used across various industries. In construction, I- and H-beams are often used in the framework of factories and high-rise buildings, bearing vertical and horizontal loads. Angle steel and channel steel are used for connecting, supporting, and reinforcing components, such as scaffolding and curtain wall frames. Round steel and square steel can be used as embedded parts, tie rods, and other load-bearing components. In machinery manufacturing, hot-rolled steel is used in equipment frames, bases, and drive shafts. For example, machine tool beds are often manufactured using a combination of cast iron and hot-rolled steel, ensuring rigidity while reducing costs. In bridge construction, large H- and I-beams are used in the main and cross beams of bridges, bearing vehicle loads and their own weight. Angle steel is used in auxiliary bridge structures, such as railings and connectors. With the continuous advancement of infrastructure construction, the application range of commonly used hot-rolled steel continues to expand.
Industry trends indicate that the production of commonly used hot-rolled steel sections is moving toward high strength, lightweighting, and customization. By developing low-alloy, high-strength steel, the thickness of steel can be reduced while maintaining strength, achieving lightweight structures. The use of high-strength hot-rolled steel sections, such as Q460 and Q690, can reduce component weight and material consumption. At the same time, manufacturers are beginning to offer customized hot-rolled steel sections with customized cross-sections, such as special-shaped and variable-section sections, to meet specific engineering needs, improving material utilization and structural safety. Furthermore, the continued promotion of green production technologies, through the use of high-efficiency heating furnaces and waste heat recovery systems, aims to reduce energy consumption and pollutant emissions during the production process. In the future, with the increasing popularity of steel structures and the development of high-end equipment manufacturing, the demand for high-performance, high-precision hot-rolled steel sections will continue to increase, driving the industry to achieve greater progress in material research and development and process innovation.
