As a metal material specialist, our company leverages mature smelting-rolling systems and strict quality control to produce professional carbon steel plates—iron-carbon alloys (0.0218%-2.11% carbon, no intentional alloying elements) with advantages of easy smelting, controllable costs and wide adaptability, serving as indispensable basics in multi-field industrial production.
The core components of carbon steel plates are iron and carbon, supplemented by small amounts of naturally occurring impurity elements such as silicon, manganese, sulfur, and phosphorus. Their performance is essentially dominated by carbon content: the higher the carbon mass fraction, the better the material's hardness and strength, but the plasticity and toughness show a decreasing trend. Our company strictly controls core component indicators, with graded control standards for harmful elements phosphorus (P) and sulfur (S): for ordinary carbon steel, P ≤ 0.045% and S ≤ 0.050%; for high-quality carbon steel, P ≤ 0.035% and S ≤ 0.035%; for high-grade high-quality steel, P ≤ 0.025% and S ≤ 0.025%. Differential adaptation of product performance is achieved through precise component regulation.
Adhering to national standards such as GB/T 700-2006 and international standards like ASTM A653/A653M, our company has established a comprehensive classification system for carbon steel plates to ensure accurate correspondence between product identification and performance parameters:
- Low-carbon steel: Carbon mass fraction < 0.25%, representative grades include Q195, Q215, and Q235 series. It possesses excellent plasticity, toughness, and weldability, suitable for cold working processes such as stamping and bending.
- Medium-carbon steel: Carbon mass fraction 0.25% ~ 0.6%, representative grades include 45# steel and 50Mn. It features a balanced combination of strength and toughness, and can meet the load-bearing requirements of mechanical parts after quenching and tempering treatment.
- High-carbon steel: Carbon mass fraction > 0.6%, representative grades include T8 and T10. It has high hardness and excellent wear resistance, mainly used in the manufacture of wear-resistant components such as tools and molds.
- Carbon structural steel: Including engineering construction steel and machine manufacturing structural steel. The grade consists of the yield strength letter (Q), yield strength value (MPa), quality grade (A/B/C/D), and deoxidation method symbol (F/Z/TZ; Z and TZ can be omitted). Examples include Q235AF (yield strength 235MPa, grade A rimmed steel) and Q355B (yield strength 355MPa, grade B killed steel), suitable for scenarios such as building steel structures and mechanical supports.
- Carbon tool steel: The grade starts with the letter T, followed by the carbon mass fraction in per mille. For example, T8A (high-grade high-quality tool steel with a carbon mass fraction of 0.8%), used for manufacturing cutting tools and measuring tools.
- Cast steel: Carbon mass fraction is controlled between 0.20% and 0.60% to avoid casting cracks caused by excessively high carbon content. The grade marking is divided into two categories: one is yield strength-tensile strength marking (e.g., ZG200-400, yield strength 200MPa, tensile strength 400MPa), and the other is carbon content marking (e.g., ZG25, carbon mass fraction 0.25%).
- Hot-rolled carbon steel plate: Rolled at a high temperature (above 1000℃), with a thickness range of 2.0 ~ 200mm, a black-brown oxide scale surface, and dimensions covering a width of 1000 ~ 2500mm and a length of 2000 ~ 12000mm. It is cost-effective and has good plasticity, suitable for welding and cutting processes.
- Cold-rolled carbon steel plate: Further rolled from hot-rolled plates at room temperature, with a thickness of 0.3 ~ 6.0mm, high surface finish, and a dimensional accuracy error of ≤ ±0.02mm. It has higher strength than hot-rolled plates, suitable for scenarios requiring high surface quality such as home appliance casings and automobile body panels.
Our company has established a full-process closed-loop production system from raw material selection to finished product delivery, with key process links as follows:
High-quality scrap steel, pig iron, and molten iron are selected as raw materials. The chemical composition of raw materials is 100% inspected by spectral analysis equipment to ensure that the content of elements such as carbon and silicon meets the preset formula, preventing unqualified raw materials from entering the production process.
The converter primary smelting process is adopted to remove impurity elements from the raw materials and precisely control the end-point carbon content. The molten steel after primary smelting enters the LF furnace for refining. Through bottom argon blowing stirring, calcium treatment, and soft blowing processes, deep desulfurization and deep deoxidation are achieved, the purity of molten steel is improved, and the quantity and size of inclusions are reduced.
The refined molten steel is cast at a low superheat through a continuous caster. Advanced technologies such as a strong cooling mold and low casting speed control are adopted to strictly regulate the molten steel temperature in the tundish (fluctuation range ≤ ±5℃) and cooling water volume, effectively reducing internal cracks and segregation defects in continuous casting billets and providing high-quality billets for subsequent rolling.
After surface cleaning, the continuous casting billets enter the heating furnace. The heating temperature (1150 ~ 1250℃) and holding time are controlled in sections to avoid billet damage caused by thermal stress. Hot rolling adopts multi-pass rough rolling + finish rolling. The computer control system adjusts the rolling mill pressure and speed in real time to ensure the uniformity of steel plate thickness. Cold rolling is performed below the recrystallization temperature to improve the strength and surface finish of the steel plate.
- Pickling: Remove the oxide scale on the surface after rolling to lay the foundation for subsequent processing.
- Leveling and straightening: High-precision straightening machines are used to control the flatness error of the steel plate to ≤ 3mm/m.
- Coating protection: Provide surface treatments such as anti-rust paint and galvanizing according to customer requirements to improve corrosion resistance.
Our company has established a three-level quality inspection system to ensure that each batch of products meets standard requirements:
Spectral analysis of chemical composition and random inspection of mechanical properties are conducted on incoming raw materials. Unqualified key indicators result in direct rejection.
- Smelting stage: Real-time monitoring of the chemical composition and temperature of molten steel, with samples retained for each heat.
- Rolling stage: Online thickness gauges and surface defect detectors are used to real-time monitor the thickness and surface quality of steel plates. The machine is shut down immediately for processing if defects such as cracks and inclusions are found.
- Heat treatment stage: For products requiring quenching and tempering treatment, the quenching temperature (820 ~ 860℃), tempering temperature (550 ~ 650℃), and holding time are strictly controlled to ensure stable mechanical properties.
- Dimensional inspection: Laser rangefinders are used to detect the thickness, width, and length of steel plates, with deviations complying with the GB/T 709-2016 standard.
- Mechanical property testing: Tensile tests (measuring yield strength, tensile strength, and elongation), bending tests, and impact tests (low-temperature impact energy Akv ≥ 27J at room temperature) are conducted on samples from each batch of products.
- Metallographic analysis: Detect grain size and tissue uniformity to ensure no abnormal structures.
- Surface inspection: Magnetic particle inspection or penetrant inspection is used to check for surface microcracks and other defects.
Relying on precise performance regulation and specification diversity, our carbon steel plates cover the application needs of multiple industries:
- Construction industry: Q235 and Q355 series hot-rolled plates are used for steel structure beams, columns, roof trusses, and bridge girders. They have excellent weldability and can withstand heavy loads and outdoor environmental erosion.
- Machinery manufacturing: Medium-carbon steel plates such as 45# steel and 50Mn are used for gears, shafts, connecting rods, and other components, meeting strength requirements after heat treatment. High-carbon steel plates are used for wear-resistant liners of mining machinery.
- Automobile manufacturing: Cold-rolled low-carbon steel plates are used for car bodies and doors due to their good stamping formability; hot-rolled plates are used for chassis components with strong load-bearing capacity.
- Petrochemical and power industry: High-quality carbon steel plates are used for manufacturing pipelines, storage tanks, and boiler components, with stable high-pressure and high-temperature resistance.
- Home appliance manufacturing: Cold-rolled plates are used for the casings of refrigerators and washing machines, featuring high surface finish and facilitating subsequent coating.
