The Manufacturing Process of Hot Finish EN 10210 S355J2H CHS

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The Manufacturing Process of Hot Finish EN 10210 S355J2H Circular Hollow Section

The production of Hot Finish EN 10210 S355J2H Circular Hollow Section (CHS) involves a series of precisely controlled processes to ensure the final product meets stringent standards for structural applications. This comprehensive overview outlines the key stages in the manufacturing process of hot-finished CHS, highlighting the importance of each step in achieving superior mechanical properties, dimensional accuracy, and surface finish.

Raw Material Selection and Preparation

The manufacturing process of Hot Finish EN 10210 S355J2H CHS begins with selecting high-quality raw materials. The base material is typically steel billets or slabs that meet the chemical composition requirements specified by the EN 10210 standard for S355J2H grade. These materials are sourced from reputable suppliers to ensure consistency and reliability.

Billet Heating:

The selected steel billets are heated in a furnace between 1200°C and 1300°C. This high temperature is crucial for the necessary plasticity for subsequent forming processes.

Piercing and Rolling

Piercing:

Once heated, the billets are transferred to a piercing mill, undergoing rotary piercing. During this process, a rotary piercer, consisting of two large rollers and a piercing mandrel, transforms the solid billet into a hollow shell. The high temperatures ensure the material is sufficiently pliable to form a seamless tube.

Elongation:

The hollow shell is then elongated using a series of rolling mills. These mills progressively reduce the diameter and wall thickness of the shell while increasing its length. This stage involves several passes through the mills to achieve the desired dimensions and improve the uniformity of the material’s structure.

Sizing and Shaping

Sizing Mill:

After elongation, the tube enters the sizing mill, which is further reduced to the precise outer diameter and wall thickness required for the final product. The sizing process ensures that the circular hollow section maintains its dimensional accuracy and uniformity.

Shaping and Calibration:

To achieve the exact circular shape, the tube passes through calibration rolls. These rolls refine the tube’s roundness and prepare it for the final finishing process. Calibration is crucial for maintaining the tight tolerances specified by the EN 10210 standard.

Heat Treatment

Normalization:

To enhance the steel’s mechanical properties, the tubes undergo normalization. They are reheated to a temperature above the critical range and then air-cooled. This heat treatment refines the grain structure, improves toughness, and ensures uniformity in mechanical properties throughout the section.

Inspection and Testing

Nondestructive Testing:

After normalization, the tubes are subjected to various nondestructive tests (NDT) to detect any internal or surface defects. Techniques such as ultrasonic testing, eddy current testing, and magnetic particle inspection are commonly used. These tests ensure the tubes’ structural integrity and reliability.

Dimensional Inspection:

Each tube undergoes rigorous dimensional inspection to verify that it meets the specified tolerances for diameter, wall thickness, and length. Any deviations are corrected to ensure compliance with the EN 10210 standard.

Cutting and Finishing

Cutting to Length:

The long tubes are cut into standard lengths or to customer specifications using high-precision cutting equipment. This step ensures the final products are ready for construction and other applications.

Surface Finishing:

The tubes are then subjected to surface finishing processes such as sandblasting or pickling to remove any scale or surface imperfections. This step enhances the aesthetic appearance and prepares the surface for subsequent coating or painting.

Final Quality Control

Final Inspection:

A final quality control inspection ensures that each tube meets all specified requirements. This includes verifying mechanical properties such as yield strength, tensile strength, and impact toughness and ensuring compliance with dimensional and surface quality standards.

Certification and Marking:

Once the tubes pass all inspections, they are certified according to EN 10210 standards. Each tube is marked with essential information such as the grade (S355J2H), size, batch number, and manufacturer’s mark, ensuring full traceability.

Conclusion

The manufacturing process of Hot Finish EN 10210 S355J2H CHS involves a series of highly controlled and precise steps, from raw material selection to final inspection. Each stage is critical in ensuring the final product meets stringent requirements for structural applications, providing high strength, excellent toughness, and reliable performance. By adhering to these meticulous processes, manufacturers can deliver high-quality CHS products that meet the diverse needs of the construction and engineering industries.

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