Analysis of the differences in production processes for customized light and heavy steel structures

The differences in production processes for customized light and heavy steel structures stem from the fundamental differences in their load-bearing requirements, component sizes, and application scenarios. These differences ultimately manifest in the entire production process, including material selection, processing methods, core procedures, and precision control. The following provides a detailed breakdown of the specific differences between the two from key dimensions, offering clear guidance for process selection in customized production.

1. Core premise: differences in material selection (fundamental orientation of production process)

The differences in production processes are already clear from the material selection stage, as the specifications and properties of the materials directly determine the design of subsequent processing flows:

Customized light steel structure: The core material is Q235 series cold-formed steel (such as C-shaped steel, Z-shaped steel, and cold-formed thin-walled square tubes), with light hot-rolled H-shaped steel used in some scenarios. The material features a thin section and light weight (with the weight of a single component typically less than 50kg). Priority is given to ensuring the material's processability and prefabrication adaptability, as it is not required to withstand extreme loads.

Customized heavy steel structure: Mainly made of high-strength hot-rolled steel such as Q355 and Q460, common components include hot-rolled H-beams, box girders, and thick plates (with a thickness of ≥10mm, often exceeding 25mm in industrial settings). The materials must possess high tensile strength and fatigue resistance, and be suitable for complex working conditions such as heavy equipment loads and large-span stress, making the processing more challenging.

II. Core Processing Technology: Essential Differences from Molding to Joining
This is the core difference between the two production processes, which directly determines the production equipment, process complexity, and production efficiency:

1. Component forming process

Light steel structure: With "cold bending" as the core process, thin plates are continuously roll-formed at room temperature through a cold bending unit, directly producing standardized components such as C-shaped steel and Z-shaped steel without the need for high-temperature heating. The process is simple and energy-efficient. For non-standard components (such as irregular connectors), only simple cutting and punching processes are required, resulting in high forming efficiency. A single production line can produce over a thousand standard components daily.

Heavy steel structure: centered around "hot-rolled forming + welding splicing". Hot-rolled steel sections undergo high-temperature rolling at the steel mill first, and during on-site customization, thick plates also need to be cut and bent (preheating is required to avoid cold bending cracking). For complex components such as box girders and lattice columns, multiple thick plates need to be welded and spliced together to form the structure. The process includes groove processing, assembly, welding, and straightening, which is cumbersome. Furthermore, thick plates need to be preheated (preheating temperature ≥100℃) before welding, and post-weld heat treatment is required to relieve stress and prevent weld cracking.

2. Connection node processing technology

Light steel structure: The entire process adopts a "bolt connection"-oriented manufacturing technique. During component production, precise drilling (with a hole diameter error of ≤±1mm) is carried out using a CNC punching machine, and bolt connection holes are reserved. No on-site welding is required; simply ensuring accurate hole positioning enables rapid on-site assembly. The processing of nodes primarily involves "drilling + simple bending", with no complex welding procedures involved.

Heavy steel structure: Oriented towards "welding connection + high-strength bolt assistance". For node processing, component assembly and positioning must be carried out first, followed by node welding through processes such as submerged arc welding and gas shielded welding. After welding, the weld seam needs to be ground and subjected to flaw detection (such as ultrasonic flaw detection and radiographic flaw detection). At the same time, high-strength bolt holes need to be precisely machined at the nodes to ensure that both the welding quality and bolt hole position accuracy meet standards. The node processing cycle is 3-5 times that of light steel.

3. Modular prefabrication process

Light steel structure: Highly compatible with "modular prefabrication". Components such as steel columns, steel beams, wall panels, and roof panels can be pre-assembled into standardized modules (such as residential unit modules and warehouse partition modules) in the factory. All connection nodes within the module are pre-processed, requiring only overall lifting and bolt fixation on site. The modularization rate can reach over 80%, significantly shortening the on-site installation period.

Heavy steel structure: Modular prefabrication is challenging and can only be achieved through "segmented prefabrication". Due to the large weight (a single steel column can weigh several tons) and size of the components, it is impossible to pre-assemble them into complete modules. Instead, they need to be processed in sections according to the lifting capacity. Each segment of the component only completes its own processing and the pre-treatment of the end connection nodes. After on-site lifting, they are spliced and welded in sections, with a modularization rate typically less than 30%.

III. Auxiliary processes: differences in corrosion prevention and straightening

1. Anti-corrosion treatment process

Light steel structure: Due to the thin cross-section of components, corrosion has a more significant impact on the structure. The principle of anti-corrosion is "economic efficiency + comprehensive coverage". The mainstream process is "shot blasting (derusting grade Sa2.5) + electrostatic spraying". In some scenarios, hot dip galvanizing is used (for key connectors), with the coating thickness controlled at 60-80μm, which can meet the anti-corrosion needs for 10-15 years. Key treatment is required for rust-prone areas such as component edges, corners, and hole locations to avoid missing spraying.

Heavy steel structure: It demands higher anti-corrosion standards and involves more intricate processes, with "long-lasting durability" as its core principle. The process involves "sandblasting for rust removal (with a rust removal grade of Sa3) + multiple coatings". For thick plate components, a phosphating treatment is required to enhance the coating adhesion, ensuring a coating thickness of ≥120μm. For severe corrosion scenarios such as industrial plants and coastal areas, a composite anti-corrosion process involving hot-dip galvanizing and topcoating is necessary. Additionally, some critical nodes require application of anti-corrosion mastic to ensure a corrosion-resistant lifespan of over 20 years.

2. Component straightening process

Light steel structure: Deformations are often caused by minor bumps during cold bending or transportation, and the correction process is simple. Mechanical correction (such as hydraulic straightening machines) or manual correction is used to make minor adjustments to local deformations. The correction accuracy can be controlled within ±2mm, without requiring complex equipment.

Heavy steel structure: Due to welding and thick plate processing, large residual stresses are easily generated, leading to more pronounced deformations, necessitating professional correction techniques. After welding, flame correction (local heating to 600-800°C) or mechanical correction is required. For complex components such as box girders, specialized correction jigs are also necessary to ensure that the deviation in straightness and perpendicularity of the components is ≤±3mm, thereby avoiding any impact on the accuracy of on-site installation.

IV. Production equipment and efficiency differences

Light steel structure: The production equipment primarily consists of lightweight CNC equipment, such as cold-formed roll forming units, CNC punching machines, and small shearing machines. These equipment require low investment and are easy to operate. A single production line can achieve automated production, resulting in high per capita productivity. The production cycle for 1000㎡ of light steel components is approximately 7-10 days.

Heavy steel structure: It requires support from large heavy-duty equipment such as large CNC cutting machines, submerged arc welding machines, welding robots, thick plate bending machines, and cranes weighing over 50t. The equipment investment is large, the skill requirements for operators are high, and the production cycle is long. The production cycle for 1000㎡ of heavy steel components is approximately 20-30 days.

V. Core Summary: The Essential Logic of Technological Differences

The core of the customized production process for light steel structures lies in "lightweight, prefabricated, and efficient" characteristics, revolving around "cold bending + bolt connection" and adapting to batch standardized production. For heavy steel structures, the focus is on "high strength, high stability, and long-term durability", advancing around "thick plate welding + segmented processing" and emphasizing the precision of single-piece or small-batch customization. The process selection for both ultimately serves their respective load-bearing needs and application scenarios. During the production process, targeted control of key procedures is required to ensure structural safety and performance.