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Cold Drawn SS400 Bright Polished Carbon Steel Flat Bar Ground Surface GB Standard for Building Structure
Our cold-drawn SS400 flat bar features bright polished & ground surface. Complying with GB standard, this carbon steel bar offers stability and durability, ideal for building structure applications.
- Overview
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In the field of building structure engineering, the selection of structural materials is directly related to the safety, durability, and aesthetic performance of construction projects. Among numerous steel products, the Cold Drawn SS400 Bright Polished Carbon Steel Flat Bar with Ground Surface has become a core material in modern building structures due to its compliance with GB standards, excellent mechanical properties, and high-quality surface treatment. This flat bar integrates the structural stability of SS400 carbon steel, the precision of cold-drawing technology, and the decorative effect of bright polishing, perfectly meeting the dual demands of building structures for "load-bearing reliability" and "surface aesthetics". Whether in residential buildings, commercial complexes, or public infrastructure, it plays an irreplaceable role in connecting components, supporting structures, and decorative details.
The foundation of the cold-drawn SS400 flat bar's reliability lies in its high-quality SS400 carbon steel base material and strict compliance with GB standards. SS400 is a widely used carbon structural steel grade, with a carbon content ranging from 0.13% to 0.22%, which gives it excellent comprehensive mechanical properties—neither too brittle due to high carbon content nor too soft due to low carbon content. As a mandatory requirement for building structural materials, this flat bar fully complies with GB/T 700-2006 "Carbon Structural Steels" and GB/T 3078-2008 "Cold-Drawn Steel Bars" standards. According to the standards, its tensile strength reaches no less than 400MPa, yield strength is not lower than 235MPa, and elongation after fracture is over 21%, which can fully bear the static load and dynamic load in building structures, such as the stress from floor slabs, walls, and external decorations. Compared with ordinary carbon steel bars, SS400 steel has better weldability and formability, which can be easily connected with other structural components through welding, bolting, and other methods, and can be bent, cut, and processed into various shapes according to construction needs, greatly improving the flexibility of structural design.
The precision cold-drawing process is another key advantage that distinguishes this flat bar from traditional hot-rolled products. The production process starts with the selection of high-quality SS400 steel billets, which undergo strict pre-treatment processes such as acid pickling, rust removal, and annealing. Acid pickling and rust removal can completely eliminate the oxide scale and surface defects on the billet surface, while annealing treatment can soften the material, reduce internal stress, and lay a foundation for subsequent cold drawing. During the cold-drawing stage, the treated steel billet is pulled through a special flat die at room temperature. This cold-working process does not require high-temperature heating, which avoids the surface oxidation and internal grain coarsening problems caused by hot rolling. At the same time, the strong tensile force in the cold-drawing process refines the grain structure of the steel, making the internal structure more dense and uniform, and eliminating defects such as porosity and segregation. The final flat bar has extremely high dimensional accuracy: the thickness tolerance can be controlled within ±0.02mm, the width tolerance is within ±0.05mm, and the straightness is less than 0.3mm/m. This precision ensures that when the flat bar is applied to building structures, it can fit closely with other components, reducing the gap between connections, and improving the overall stability of the structure. For example, in the assembly of steel structure prefabricated parts, the high precision of the flat bar can avoid on-site secondary processing, shorten the construction period, and reduce construction costs.
The bright polished and ground surface treatment is a highlight of this product, which not only enhances its corrosion resistance but also expands its application scope in decorative fields. After cold drawing, the flat bar undergoes two-stage surface processing: first, it is ground with high-precision grinding equipment to remove the slight burrs and unevenness on the surface, making the surface flatness reach Ra ≤ 0.8μm; then, it is subjected to bright polishing treatment, which forms a smooth, bright, and mirror-like surface on the steel bar surface. This surface treatment has multiple benefits: on the one hand, the dense oxide film formed during the polishing process can effectively isolate the steel from air, water vapor, and other corrosive media, significantly improving the corrosion resistance of the flat bar. In humid environments such as basements, bathrooms, and exterior walls, it can avoid rusting and peeling, extending the service life of the building structure. On the other hand, the bright surface gives the flat bar excellent decorative performance, making it no longer just a hidden structural component but can be directly used in visible parts such as handrails, decorative grilles, and ceiling keels. For example, in high-end commercial buildings, the bright polished SS400 flat bar is used to make decorative partitions, which not only plays a role in dividing space but also adds a sense of modernity and texture to the interior environment, realizing the integration of "structure and decoration".
In building structure applications, the cold-drawn SS400 bright polished flat bar shows strong versatility and adaptability, covering multiple links from the main structure to the auxiliary decoration. In the main structure system, it is often used as a connecting rod between steel beams and columns, a support for prefabricated concrete components, and a stress bar for lightweight steel structures. Its high strength and good toughness can effectively absorb the vibration and deformation caused by earthquakes, strong winds, and other external forces, ensuring the safety of the main structure. In the secondary structure and decoration field, its application scenarios are more diverse: in residential buildings, it is used to make window frames, door frames, and balcony handrails, with the advantages of high strength, no deformation, and beautiful appearance; in commercial spaces, it is processed into decorative screens, display racks, and ceiling keels, combining practicality and aesthetics; in public infrastructure such as bridges and tunnels, it serves as a corrosion-resistant connecting component for guardrails and drainage systems, adapting to harsh outdoor environments. In addition, this flat bar can also be customized according to the specific needs of construction projects, including different thicknesses (from 2mm to 50mm), widths (from 10mm to 200mm), lengths (from 2m to 12m), and surface treatment methods (such as adding anti-fingerprint coating, galvanized layer, etc.), to meet the personalized needs of different building types.
Strict quality control system is the guarantee for the stable performance of the cold-drawn SS400 flat bar. From the purchase of raw materials to the delivery of finished products, every link is subject to rigorous testing. In the raw material inspection stage, the chemical composition and mechanical properties of SS400 steel billets are tested by spectral analysis and tensile testing machines to ensure that they meet the GB standard requirements; in the cold-drawing process, real-time monitoring of the drawing speed, die temperature, and dimensional accuracy is carried out to avoid quality problems caused by process fluctuations; after surface treatment, the surface roughness, brightness, and corrosion resistance are tested by roughness meters, gloss meters, and salt spray test machines. The salt spray test shows that the flat bar can resist corrosion for more than 480 hours in a 5% sodium chloride solution, far exceeding the industry average level. In addition, each batch of products will be accompanied by a quality inspection report, clearly marking the product model, batch number, test data, and compliance with standards, to provide a reliable basis for construction units and quality supervision departments.
Against the background of the continuous development of green building and prefabricated construction, the cold-drawn SS400 bright polished carbon steel flat bar conforms to the development trend of the construction industry with its environmental protection, high efficiency, and high performance. In terms of environmental protection, the cold-drawing process consumes less energy than hot rolling, and the waste water and waste gas generated during production are easy to treat, which meets the requirements of energy conservation and emission reduction; the long service life of the product reduces the frequency of material replacement and reduces construction waste. In terms of construction efficiency, its high precision and good processability can realize prefabricated production in the factory and on-site assembly, which greatly shortens the construction period and reduces the labor intensity of on-site workers. For example, in the construction of a prefabricated residential community, the use of this flat bar as a connecting component can reduce the on-site construction time by 30% compared with the use of traditional steel bars, and the construction quality is more controllable.
In conclusion, the Cold Drawn SS400 Bright Polished Carbon Steel Flat Bar with Ground Surface is a high-performance building structural material that integrates strength, precision, corrosion resistance, and aesthetics. It relies on the excellent properties of SS400 carbon steel, the precision processing of cold-drawing technology, and the high-quality surface treatment, and strictly complies with GB standards, providing a reliable material guarantee for the safety and durability of building structures. Whether in the main structure bearing heavy loads or the decorative parts pursuing beauty, it can play an excellent role. With the continuous progress of the construction industry, this flat bar will be more widely used in various construction projects, contributing to the development of safer, more durable, and more beautiful buildings.
Cold drawn steel profiles are precision steel products manufactured through a cold-drawing process at room temperature.
This process significantly improves dimensional accuracy, surface smoothness, and mechanical properties compared to hot-rolled steel.
They are widely used in machinery manufacturing, construction structures, automotive components, and precision equipment.
This process significantly improves dimensional accuracy, surface smoothness, and mechanical properties compared to hot-rolled steel.
They are widely used in machinery manufacturing, construction structures, automotive components, and precision equipment.
Material Grades Available
Carbon Steel: Q195, Q215, Q235, 20#, 35#, 45#, 55#
Alloy / Gear Steel: 40Cr, 20CrMo, 35CrMo, 42CrMo, 20Cr, 20CrMoTi, Q355
Free Cutting Steel: 1215, 12L14, 1144
Bearing Steel: GCr15
Spring Steel: 60Si2Mn, 65Mn
Carbon Steel: Q195, Q215, Q235, 20#, 35#, 45#, 55#
Alloy / Gear Steel: 40Cr, 20CrMo, 35CrMo, 42CrMo, 20Cr, 20CrMoTi, Q355
Free Cutting Steel: 1215, 12L14, 1144
Bearing Steel: GCr15
Spring Steel: 60Si2Mn, 65Mn
Diameter Range |
Customized (typically 3mm – 300mm) |
Length |
Standard 6 meters or customized |
Surface Finish |
Bright, smooth, no oxide scale |
Tolerance |
±0.05mm |
Shape Options |
Round / Square / Flat / Hexagonal / Special profiles |
Process |
Cold drawing, straightening, cutting, polishing |
Certification |
ISO9001 / SGS / Mill Test Certificate available |
✅ High Dimensional Precision – Tolerance up to ±0.02mm
✅ Bright Surface Finish – Smooth and oxide-free, ready for machining
✅ Enhanced Mechanical Strength – Balanced hardness and toughness
✅ High Material Utilization – Reduced machining allowance, higher efficiency
✅ Customizable Solutions – Shapes, sizes, and materials can be tailored to drawings or requirements
✅ Bright Surface Finish – Smooth and oxide-free, ready for machining
✅ Enhanced Mechanical Strength – Balanced hardness and toughness
✅ High Material Utilization – Reduced machining allowance, higher efficiency
✅ Customizable Solutions – Shapes, sizes, and materials can be tailored to drawings or requirements
Jiangsu Beitong Cold-Drawn Steel Technology Co., Ltd.
was established in 2018 with an investment of 80 million RMB.Located in Fenhu High-Tech Zone, Wujiang District, Suzhou, Jiangsu Province, the company covers an area of 35 mu (≈23,000 m²) and integrates R&D, production, and modern management.
With a team of over 60 employees, including skilled engineers and R&D professionals, Beitong specializes in the research and manufacture of precision cold-drawn steel products, serving more than 5,000 domestic and overseas customers.
Guided by technological innovation, Beitong has obtained over 10 national patents, was recognized as a Provincial Science &Technology SME (2022), achieved ISO Three-System Certification (2023), and was honored as a Specialized and Innovative SME (2024).
The company operates 50+ advanced cold-drawing production lines, equipped with mechanical performance testers, ultrasonic flaw detectors, and full laboratory analysis systems, ensuring reliable quality and strong technical capability.
Main Products & Applications
* Elevator guide rails – exported to the Middle East
* Automotive parts materials – supplied to major brands such as BYD, Tesla, Toyota, SAIC, GAC, Huawei, and CATL
* Chain flat steel and precision shafts
* Free-cutting steel – directly supplied to top domestic automation enterprises
Our products are widely used in construction machinery, automotive, aerospace, petroleum, coal mining, national defense, textile machinery, machine tools, agricultural equipment, fitness equipment, and elevators.
With solid technology and stable quality, Beitong warmly welcomes customers worldwide for long-term cooperation and mutual
success.
With a team of over 60 employees, including skilled engineers and R&D professionals, Beitong specializes in the research and manufacture of precision cold-drawn steel products, serving more than 5,000 domestic and overseas customers.
Guided by technological innovation, Beitong has obtained over 10 national patents, was recognized as a Provincial Science &Technology SME (2022), achieved ISO Three-System Certification (2023), and was honored as a Specialized and Innovative SME (2024).
The company operates 50+ advanced cold-drawing production lines, equipped with mechanical performance testers, ultrasonic flaw detectors, and full laboratory analysis systems, ensuring reliable quality and strong technical capability.
Main Products & Applications
* Elevator guide rails – exported to the Middle East
* Automotive parts materials – supplied to major brands such as BYD, Tesla, Toyota, SAIC, GAC, Huawei, and CATL
* Chain flat steel and precision shafts
* Free-cutting steel – directly supplied to top domestic automation enterprises
Our products are widely used in construction machinery, automotive, aerospace, petroleum, coal mining, national defense, textile machinery, machine tools, agricultural equipment, fitness equipment, and elevators.
With solid technology and stable quality, Beitong warmly welcomes customers worldwide for long-term cooperation and mutual
success.
1. When can you produce the samples?
Usually, it takes 5–7 days to produce samples.
2. What is your minimum order quantity (MOQ)?
For cold-drawn steel profiles, we usually offer two purchasing options - LTL (less than truckload) and bulk order, starting from 2 tons. The specific quantity can be discussed.
3. What is your delivery time?
For customized product orders, we can arrange shipment within 30 days after receiving the deposit.
4. Which ports do you ship from?
We usually ship from Shanghai Port.
5. What are your payment terms?
Normally 30% T/T deposit in advance, and the balance against the copy of the Bill of Lading.
6. Where is your company located?
Our factory is located in Jiangsu Province, China.
7. What are your main products?
We specialize in cold-drawn steel:
* Cold drawn round bar
* Cold drawn square bar
* Cold drawn flat bar
* Cold drawn hexagonal bar
* Cold drawn special-shaped bar
Material Grades:
* Carbon steel: Q215, Q195, Q235, 20#, 35#, 45#, 55#
* Alloy / gear steel: Q355, 40Cr, 20CrMo, 35CrMo, 42CrMo, 20Cr, 20CrMoTi
* Free cutting steel: 1215, 12L14, 1144
* Bearing steel: GCr15
* Spring steel: 60Si2Mn, 65Mn
Service Commitment:
24-Hour Feedback, 48-Hour Solution
8. What types of carbon steel bars are there?
* Low carbon steel bar: Low carbon content, good toughness, suitable for welding and machining.
* Medium carbon steel bar: Balanced strength and toughness, ideal for mechanical parts.
* High carbon steel bar: High hardness, used for tools and springs.
9. Will carbon steel bars rust?
Yes. Carbon steel bars can rust in humid environments. Coating, galvanizing, or heat treatment can improve corrosion resistance.
10. What are the common applications of carbon steel bars?
* Building structures (rebar, support rods)
* Mechanical parts (shafts, bolts)
* Tools (cutting tools, drill bits)
11. How to determine the size specifications of carbon steel bars?
Classified by diameter and length.
Diameter: from a few millimeters to several hundred millimeters.
Length: typically 6 meters or customized.
12. What is the fatigue resistance of carbon steel bars?
Fatigue performance depends on carbon content, microstructure, and surface quality.
It can be improved by surface treatment (rolling, polishing) or optimized heat treatment.
13. What should be noted when welding carbon steel bars?
* Low carbon steel: easy to weld, but avoid overheating.
* High carbon steel: prone to cracking during welding; preheating and post-heat treatment are recommended.
14. Can I get samples?
Yes, samples are available.
15. Do you have a factory?
Yes, we have our own factory in Jiangsu, and warmly welcome your visit.
We are a professional cold-drawn steel manufacturer providing OEM & ODM services.
Usually, it takes 5–7 days to produce samples.
2. What is your minimum order quantity (MOQ)?
For cold-drawn steel profiles, we usually offer two purchasing options - LTL (less than truckload) and bulk order, starting from 2 tons. The specific quantity can be discussed.
3. What is your delivery time?
For customized product orders, we can arrange shipment within 30 days after receiving the deposit.
4. Which ports do you ship from?
We usually ship from Shanghai Port.
5. What are your payment terms?
Normally 30% T/T deposit in advance, and the balance against the copy of the Bill of Lading.
6. Where is your company located?
Our factory is located in Jiangsu Province, China.
7. What are your main products?
We specialize in cold-drawn steel:
* Cold drawn round bar
* Cold drawn square bar
* Cold drawn flat bar
* Cold drawn hexagonal bar
* Cold drawn special-shaped bar
Material Grades:
* Carbon steel: Q215, Q195, Q235, 20#, 35#, 45#, 55#
* Alloy / gear steel: Q355, 40Cr, 20CrMo, 35CrMo, 42CrMo, 20Cr, 20CrMoTi
* Free cutting steel: 1215, 12L14, 1144
* Bearing steel: GCr15
* Spring steel: 60Si2Mn, 65Mn
Service Commitment:
24-Hour Feedback, 48-Hour Solution
8. What types of carbon steel bars are there?
* Low carbon steel bar: Low carbon content, good toughness, suitable for welding and machining.
* Medium carbon steel bar: Balanced strength and toughness, ideal for mechanical parts.
* High carbon steel bar: High hardness, used for tools and springs.
9. Will carbon steel bars rust?
Yes. Carbon steel bars can rust in humid environments. Coating, galvanizing, or heat treatment can improve corrosion resistance.
10. What are the common applications of carbon steel bars?
* Building structures (rebar, support rods)
* Mechanical parts (shafts, bolts)
* Tools (cutting tools, drill bits)
11. How to determine the size specifications of carbon steel bars?
Classified by diameter and length.
Diameter: from a few millimeters to several hundred millimeters.
Length: typically 6 meters or customized.
12. What is the fatigue resistance of carbon steel bars?
Fatigue performance depends on carbon content, microstructure, and surface quality.
It can be improved by surface treatment (rolling, polishing) or optimized heat treatment.
13. What should be noted when welding carbon steel bars?
* Low carbon steel: easy to weld, but avoid overheating.
* High carbon steel: prone to cracking during welding; preheating and post-heat treatment are recommended.
14. Can I get samples?
Yes, samples are available.
15. Do you have a factory?
Yes, we have our own factory in Jiangsu, and warmly welcome your visit.
We are a professional cold-drawn steel manufacturer providing OEM & ODM services.
