In-depth analysis of cold-rolled and hot-rolled plate processing technology and practical strategies for plate cost optimization

In-depth analysis of cold-rolled and hot-rolled plate processing technology and practical strategies for plate cost optimization

 

In the field of metal sheet processing, cold-rolled sheet processing and hot-rolled sheet processing are two core process routes. A deep understanding of their differences and the implementation of effective sheet cost optimization strategies are crucial to the competitiveness of enterprises.

Core process comparison: the essential difference between cold rolling and hot rolling

Hot-rolled sheet process:

Process: The steel billet is heated to the austenitizing temperature (about 1100°C or above) → High temperature and high pressure rolling to the target thickness → Coiling or shearing.

Core features: High temperature plastic deformation, weak work hardening effect.

Performance: There is iron oxide scale on the surface (need to be removed by pickling), and the dimensional accuracy and surface finish are relatively low; the mechanical properties are moderate, usually with slightly lower strength and better plasticity; there is anisotropy.

Typical applications: Building structures (beams, columns), pipelines, truck chassis, containers, equipment shell substrates, etc., which do not have strict surface requirements and emphasize strength and weldability.

Cold rolled sheet processing:

Process: hot rolled coil → pickling to remove scale → multiple rolling at room temperature (accompanied by work hardening) → annealing (plasticity recovery) → (optional) finishing (flattening, straightening, coating, etc.).

Core features: plastic deformation at room temperature, accompanied by significant work hardening.

Performance: smooth and clean surface, high dimensional accuracy; excellent comprehensive mechanical properties (high strength, high hardness, good elongation) can be obtained after annealing; high performance consistency.

Typical applications: automotive body panels, high-end home appliance housings (refrigerators, washing machines), precision instrument parts, high-end furniture, coated substrates (galvanized, tinned), etc., which have extremely high requirements for dimensional accuracy, surface quality, and formability.

Comparison table of core characteristics of cold-rolled and hot-rolled plates:
Characteristics Hot-rolled plate process Cold-rolled plate processing
Processing temperature High temperature (>1100°C) Room temperature
Surface state There is iron oxide scale, relatively rough (improved after pickling) High finish, can be used directly
Dimensional accuracy Relatively low (±0.1-0.2mm or higher) High (±0.01-0.05mm)
Mechanical properties Moderate strength, good plasticity, and directionality High strength and hardness, good plasticity after annealing, and uniform performance
Thickness range Wide (usually >1.2mm, up to tens of mm) Thin (usually 0.15mm - 3mm or slightly thicker)
Processing procedures Relatively simple (heating → rolling) Complex (pickling → cold rolling → annealing → finishing)
Cost structure Raw materials and energy (heating) costs account for a large proportion There are many processing procedures, and the manufacturing cost (rolling, annealing) accounts for a significant proportion

Plate cost optimization strategy: precise policy implementation, cost reduction and efficiency improvement

1. Source optimization: precise material selection and specification design

Material selection on demand: Avoid excess performance. For parts that do not require appearance, such as structural parts and internal support parts, give priority to hot-rolled plate process products that meet mechanical properties and make full use of their cost advantages. Cold-rolled plate processing products are only selected when there are strict requirements on surface, precision, and deep drawing.

Optimize specifications: Accurately calculate the load-bearing requirements and select the most economical thickness and grade within the safety margin. Work closely with suppliers to give priority to the steel mill's stock specifications to reduce the additional costs brought by customization.

2. Process leanness: improve efficiency and reduce losses

Hot rolling process optimization:

Waste heat utilization: Explore post-rolling waste heat recovery and utilization technology (such as power generation and preheating steel billets) to significantly reduce heating energy consumption.

Improve the yield rate: Optimize the rolling procedures and plate shape control technology to reduce head and tail cutting losses and edge defects; promote hot loading and hot delivery processes to reduce secondary heating energy consumption.

Efficient descaling: Use high-efficiency means such as high-pressure water descaling to reduce the generation of iron oxide scale and the burden of subsequent pickling.

Cold rolling process optimization:

Rolling lubrication upgrade: Use efficient and environmentally friendly rolling fluid to reduce rolling force and energy consumption, extend the life of the roller, and improve surface quality.

Intelligent control of annealing process: Apply mathematical models and online monitoring to achieve precise control of annealing temperature, time, and atmosphere, reduce energy consumption while ensuring stable performance.

Reduce turnover between processes: Optimize production planning and logistics, shorten the inventory time and transportation distance of work-in-progress.

3. Production management: Get benefits from waste

Optimize cutting plan: Use professional CAD/CAM nesting software to achieve intelligent optimization of plate cutting, maximize material utilization, and reduce corners. Even a small percentage increase can bring significant plate cost optimization in mass production.

Strict control of process loss: Establish a full-process loss tracking system from raw material storage to finished product delivery. Focus on controlling the pickling loss, rolling strip breakage, trimming loss, surface scratches and other links. Set loss targets and continuously improve.

Equipment maintenance upgrade: Implement predictive maintenance to ensure the efficient and stable operation of key equipment (rolling mills, annealing furnaces, pickling lines) and reduce unplanned downtime. Evaluate the return on investment of introducing automated and intelligent equipment (such as automatic surface inspection and robot handling) to improve efficiency and quality stability.

4. Circular economy: turning waste into treasure

Waste recycling: Establish a complete in-plant scrap steel and scrap edge material classification and recycling system. Cooperate with qualified recyclers to ensure efficient and compliant waste treatment and generate revenue. Explore the possibility of directly recycling some clean waste for smelting or lower-requirement products.

Conclusion: Wise choice, continuous optimization
Cold-rolled plate processing and hot-rolled plate processes each have irreplaceable advantages. The core of achieving true plate cost optimization lies in:

Accurate matching: Based on the mechanical, surface, and precision requirements of the final use of the product, scientifically select the most cost-effective plate type and process.

Lean throughout: From design and material selection, procurement specifications to production and manufacturing, and waste management, we implement refined cost control throughout the entire process.

Technology-driven: We actively embrace intelligent, automated technology and process innovation to continuously improve efficiency, quality and resource utilization.

By deeply understanding the essence of the process and systematically implementing optimization strategies, companies can effectively control sheet costs and gain market competitive advantages while ensuring quality and delivery.