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Mild Steel Plate: Properties, Manufacturing, Applications, and Market Trends

Issuing time:2025-09-26 17:01

低碳钢板.jpg1. Introduction

Mild steel plate, also known as low - carbon steel plate, is a widely used material in the manufacturing, construction, and engineering industries. It is characterized by its relatively low carbon content, which gives it unique mechanical properties that make it suitable for a vast range of applications. Unlike high - carbon steel, which is hard but brittle, mild steel plate strikes a balance between strength, ductility, and weldability, making it a go - to choice for many professionals. In this article, we will delve into the properties, manufacturing process, applications, and market trends of mild steel plate, providing a comprehensive overview of this essential material.
2. Properties of Mild Steel Plate
2.1 Chemical Composition
The key feature of mild steel plate is its low carbon content, typically ranging from 0.05% to 0.25%. This low carbon level is what differentiates it from other types of steel. In addition to carbon, mild steel plate contains small amounts of other elements such as manganese (usually between 0.30% and 0.60%), which enhances its strength and hardenability. It may also have trace amounts of silicon, phosphorus, and sulfur, but these are kept at low levels to avoid adverse effects on the material's properties. For example, excessive phosphorus can increase brittleness, while too much sulfur can lead to hot shortness during processing.
2.2 Mechanical Properties

  • Strength: Mild steel plate has a moderate tensile strength, usually between 370 MPa and 480 MPa. While it is not as strong as high - strength steel, its strength is sufficient for many common applications, such as general structural components.

  • Ductility: One of the notable properties of mild steel plate is its high ductility. It can be easily stretched, bent, and formed into various shapes without breaking. This ductility makes it ideal for processes like rolling, forging, and stamping. For instance, it can be formed into pipes, tubes, and automotive parts with relative ease.

  • Weldability: Mild steel plate is highly weldable. The low carbon content prevents the formation of hard and brittle zones in the weld, ensuring good weld strength and integrity. This property makes it widely used in the fabrication of structures and equipment that require welding, such as bridges, ships, and pressure vessels.

  • Toughness: It exhibits good toughness, meaning it can absorb energy without fracturing under impact loads. This is particularly important in applications where the material may be subjected to sudden shocks or vibrations, like in machinery components.

2.3 Physical Properties

  • Density: The density of mild steel plate is approximately 7.85 g/cm³, which is similar to other types of steel. This density gives it a certain weight, which is a consideration in structural design.

  • Thermal Conductivity: It has a thermal conductivity of about 50 W/(m·K) at room temperature. This property allows it to conduct heat relatively well, making it suitable for applications where heat transfer is required, such as in heat exchangers.

  • Electrical Conductivity: Mild steel plate is a moderate conductor of electricity. While not as good as copper or aluminum, it is used in some electrical applications where strength is also a factor.

  • Corrosion Resistance: Compared to stainless steel, mild steel plate has relatively poor corrosion resistance. It tends to rust when exposed to moisture and oxygen. To improve its corrosion resistance, it is often coated with materials such as zinc (galvanized mild steel plate), paint, or other protective coatings.

3. Manufacturing Process of Mild Steel Plate
The manufacturing of mild steel plate involves several key steps, each of which plays a crucial role in determining the quality and properties of the final product.
3.1 Raw Material Preparation
The main raw material for mild steel plate is iron ore. First, iron ore is mined and then processed to remove impurities such as silica, alumina, and phosphorus. The processed iron ore is then mixed with coke and limestone in a blast furnace. The coke acts as a fuel and a reducing agent, while the limestone helps to remove the impurities as slag. In the blast furnace, the iron ore is reduced to molten iron, also known as pig iron. Pig iron has a high carbon content (usually between 3.5% and 4.5%) and other impurities, so it needs further processing.
3.2 Steelmaking
The next step is steelmaking, where pig iron is converted into mild steel. There are several methods for steelmaking, including the basic oxygen furnace (BOF) process and the electric arc furnace (EAF) process.

  • Basic Oxygen Furnace (BOF) Process: In the BOF process, molten pig iron is poured into a converter, and pure oxygen is blown into the molten iron at high speed. The oxygen reacts with the carbon and other impurities in the pig iron, oxidizing them to form gases (such as carbon dioxide) and slag. The process is fast, typically taking around 30 to 40 minutes, and is suitable for large - scale production of mild steel.

  • Electric Arc Furnace (EAF) Process: The EAF process uses electricity to melt scrap steel, which is a major raw material. Scrap steel is loaded into the furnace, and an electric arc is formed between the electrodes and the scrap, generating heat to melt the scrap. Once the scrap is melted, alloying elements can be added to adjust the composition of the steel to meet the required specifications. The EAF process is more flexible and can be used to produce a wide range of steel grades, including mild steel. It is also more environmentally friendly as it uses scrap steel, reducing the need for mining and processing iron ore.

3.3 Casting
After steelmaking, the molten mild steel is cast into semi - finished products called slabs. The casting process can be either continuous casting or ingot casting.

  • Continuous Casting: This is the most common method used today. The molten steel is poured into a water - cooled copper mold, where it solidifies into a solid shell. The shell is then pulled out of the mold continuously and passed through a series of secondary cooling zones to further solidify the steel. The continuous casting process produces slabs of uniform quality and dimensions, with high productivity.

  • Ingot Casting: In this method, the molten steel is poured into large molds called ingots. The ingots are allowed to cool and solidify, and then they are reheated and rolled into slabs. Ingot casting is less efficient than continuous casting and is mainly used for producing large - sized slabs or special - grade steels.

3.4 Rolling
The slabs are then reheated to a high temperature (usually between 1100°C and 1300°C) and rolled into plates using a rolling mill. The rolling process involves passing the slab through a series of rolls that apply pressure to reduce the thickness of the slab and increase its length and width. There are two main types of rolling: hot rolling and cold rolling.

  • Hot Rolling: Hot rolling is done at a temperature above the recrystallization temperature of the steel. This makes the steel more ductile and easier to roll. Hot - rolled mild steel plate has a rough surface finish and a slightly irregular shape. It is commonly used in applications where surface finish is not a critical factor, such as in structural components and heavy machinery.

  • Cold Rolling: Cold rolling is done at a temperature below the recrystallization temperature. After hot rolling, the steel plate is pickled to remove the oxide scale on the surface, and then it is passed through cold rolls. Cold rolling results in a smoother surface finish, tighter dimensional tolerances, and increased strength and hardness of the steel plate. Cold - rolled mild steel plate is used in applications where a high - quality surface finish and precise dimensions are required, such as in automotive body panels, electrical appliances, and furniture.

3.5 Heat Treatment (Optional)
In some cases, mild steel plate may undergo heat treatment to further improve its properties. Common heat treatment processes include annealing, normalizing, and tempering.

  • Annealing: Annealing involves heating the steel plate to a specific temperature, holding it at that temperature for a certain period, and then cooling it slowly. This process relieves internal stresses, softens the steel, and improves its ductility and machinability.

  • Normalizing: Normalizing is similar to annealing, but the steel is cooled in air instead of slowly. This process refines the grain structure of the steel, improving its strength and toughness.

  • Tempering: Tempering is usually done after quenching (a process where the steel is heated and then rapidly cooled to harden it). However, mild steel is not typically quenched because of its low carbon content. But in some special cases, if mild steel is hardened by other means, tempering can be used to reduce brittleness and adjust the hardness and toughness.

3.6 Surface Treatment
To improve the corrosion resistance and appearance of mild steel plate, various surface treatment methods can be applied.

  • Galvanizing: Galvanizing is a common surface treatment where a layer of zinc is applied to the surface of the steel plate. The zinc layer acts as a barrier, protecting the steel from corrosion. Galvanized mild steel plate is widely used in outdoor applications, such as roofing, fencing, and automotive parts.

  • Painting: Painting is another simple and effective way to protect mild steel plate from corrosion. A layer of paint is applied to the surface, which prevents moisture and oxygen from coming into contact with the steel. Different types of paints, such as epoxy paints and polyurethane paints, can be used depending on the specific application requirements.

  • Chrome Plating: Chrome plating provides a hard, smooth, and corrosion - resistant surface. It is often used in applications where a high - quality decorative finish is required, such as in furniture, automotive trim, and bathroom fixtures.

4. Applications of Mild Steel Plate
Due to its excellent combination of properties, mild steel plate finds applications in a wide range of industries.
4.1 Construction Industry
The construction industry is one of the largest consumers of mild steel plate. It is used in the construction of buildings, bridges, tunnels, and other infrastructure projects.

  • Building Construction: In building construction, mild steel plate is used for manufacturing structural components such as beams, columns, and trusses. These components provide support to the building and ensure its stability. Hot - rolled mild steel plate is commonly used for this purpose because of its high strength and ductility. It is also used in the construction of floors, roofs, and walls. For example, it can be used as a base material for concrete slabs or as a cladding material for exterior walls.

  • Bridge Construction: Bridges require materials that can withstand heavy loads and harsh environmental conditions. Mild steel plate, especially galvanized or painted mild steel plate, is used in the construction of bridge decks, girders, and piers. Its high weldability allows for easy fabrication of large bridge structures, and its toughness ensures that the bridge can withstand the impact of traffic and environmental factors such as wind and earthquakes.

  • Tunnel Construction: In tunnel construction, mild steel plate is used for lining the tunnel walls and ceilings. It provides a strong and durable barrier against the surrounding soil and rock, preventing the tunnel from collapsing. The ductility of mild steel plate allows it to adapt to minor movements in the tunnel, reducing the risk of cracking.

4.2 Manufacturing Industry
The manufacturing industry relies heavily on mild steel plate for the production of various machinery, equipment, and consumer goods.

  • Machinery Manufacturing: Mild steel plate is used in the manufacturing of machine frames, bases, and components. Its high strength and rigidity make it suitable for supporting the moving parts of machinery, while its machinability allows for easy processing into complex shapes. For example, it is used in the production of lathes, milling machines, and industrial robots.

  • Automotive Industry: The automotive industry uses a large amount of mild steel plate in the production of car bodies, chassis, and other components. Cold - rolled mild steel plate is preferred for car bodies because of its smooth surface finish and precise dimensions, which allow for easy stamping and forming into complex shapes. It is also used in the production of engine parts, such as cylinder blocks and crankshafts, due to its good strength and toughness.

  • Appliance Manufacturing: Mild steel plate is used in the manufacturing of household appliances such as refrigerators, washing machines, and ovens. It is used for the outer casings, inner liners, and structural components of these appliances. The corrosion resistance of mild steel plate can be improved by coating it with paint or other protective materials, ensuring that the appliances have a long service life.

4.3 Energy Industry
The energy industry, including oil and gas, power generation, and renewable energy, uses mild steel plate in various applications.

  • Oil and Gas Industry: In the oil and gas industry, mild steel plate is used for the construction of pipelines, storage tanks, and offshore platforms. Pipelines made of mild steel plate are used to transport oil and gas from the production site to the refinery or distribution center. The high strength and weldability of mild steel plate make it suitable for withstanding the high pressure and harsh environmental conditions in the oil and gas industry. Storage tanks are used to store oil, gas, and other petroleum products, and mild steel plate is chosen for its durability and low cost. Offshore platforms require materials that can withstand the corrosive effects of seawater and strong winds, and galvanized or coated mild steel plate is often used for this purpose.

  • Power Generation Industry: The power generation industry uses mild steel plate in the construction of power plants, including thermal power plants, nuclear power plants, and hydropower plants. In thermal power plants, mild steel plate is used for the construction of boilers, steam turbines, and other equipment. Boilers require materials that can withstand high temperatures and pressures, and mild steel plate with appropriate heat treatment can meet these requirements. In nuclear power plants, mild steel plate is used for the construction of containment structures and other safety - related components, where its strength and toughness are crucial. In hydropower plants, mild steel plate is used for the construction of turbines, generators, and dams.

  • Renewable Energy Industry: The renewable energy industry, such as wind power and solar power, also uses mild steel plate. In wind power, mild steel plate is used for the construction of wind turbine towers and nacelles. The towers need to be tall and strong to support the wind turbine blades, and mild steel plate is a cost - effective choice for this purpose. The nacelles, which house the generator and other components, are also made of mild steel plate. In solar power, mild steel plate is used for the construction of solar panel frames, which provide support to the solar panels.

4.4 Other Applications

  • Shipbuilding Industry: Mild steel plate is widely used in the shipbuilding industry for the construction of ship hulls, decks, and other structural components. Ship hulls need to be strong, durable, and corrosion - resistant, and mild steel plate, especially marine - grade mild steel plate with special coatings, meets these requirements.

  • Railway Industry: In the railway industry, mild steel plate is used for the construction of railway tracks, train bodies, and other components. Railway tracks need to withstand heavy loads and repeated impacts, and mild steel plate with high strength and wear resistance is used for this purpose. Train bodies are made of mild steel plate for its strength and light weight, which helps to improve the speed and efficiency of the trains.

  • Agricultural Machinery: Mild steel plate is used in the manufacturing of agricultural machinery such as tractors, harvesters, and plows. These machines need to be strong and durable to withstand the harsh conditions in the field, and mild steel plate is suitable for this purpose. It is also used in the production of agricultural storage equipment, such as grain silos.


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