Ultimate Guide of Iron and Steel

Of the many metals, none is more widely used and in greater quantity than iron, which became popular in China more than 2,000 years ago for building production tools and weapons.

Nowadays, iron is used in a wide range of industries due to its unique physical and chemical properties.

Physical Properties

Pure iron appears silver-white when the surface is not oxidised, has good thermal and electrical conductivity, and is magnetic especially when worked into specific forms. Iron has several isotopes and its crystal structure changes with temperature.

Iron is not as ductile and malleable as metals such as copper or aluminium, but can be formed by casting, forging, stamping and other processes to meet a wide range of shapes and sizes.

Chemical Properties

Iron tends to react with oxygen in the air to form oxides, a process known as rusting, and the oxides are rust. In order to prevent rusting, surface treatment is usually applied to iron, such as painting, powder coating and electroplating. The corrosion resistance of iron can also be enhanced by adding metals such as chromium and nickel to form alloys such as stainless steel.

Iron has good weldability and can be connected to other metals or itself through the welding process. This makes iron very useful in the manufacture of large structural parts and complex components.

Compared to rare metals, iron is abundant and cheap to mine, making it the metal of choice for many industries. At the same time, iron is a recyclable resource, and used iron products can be smelted and reprocessed into new iron products, realising the recycling and efficient use of resources.

Types of Steel

There are many types of steel, which can be classified into many types according to its composition and processing as well as its use.

The common types are mainly as follows:

1. Pig Iron

Pig iron is a primary product extracted from iron ore, with a high carbon content of 2%-4.5%, and contains many impurities. For example, silicon, manganese, sulfur, phosphorus.

Toughness, plasticity and weldability is poor, but has good castability, suitable for casting process. Such as for casting iron pots, iron pipe and machine tool bed.

2. Carbon Steel

Steel is added to iron in carbon and other metal elements in the composition of the alloy material. According to the size of its carbon content can be divided into low carbon steel (carbon content <0.25%), medium carbon steel (carbon content of 0.25% – 0.6%), high carbon steel (carbon content > 0.6%).

Among them, mild steel has better plasticity and welding properties, and can be used to make steel plates, reinforcement bars and pipes.

Medium carbon steel has high strength and hardness and is used to make gears, shafts, springs, etc.

High-carbon steel is extremely hard and wear-resistant, suitable for making props, moulds, etc.

3. Alloy Steel

Alloy steel is a steel material to which other alloying elements have been added in addition to carbon. By adding different alloying elements, specific physical, chemical and mechanical properties can be obtained. Alloy steel is widely used in the manufacture of special tools, bearings and high-strength structural parts.

4. Cast Iron

Cast iron has a high carbon content (2%-4%) and also contains a certain percentage of silicon to enhance fluidity and facilitate casting. Has good casting properties, but brittle. Commonly used in the manufacture of castings, such as pipes, mechanical parts, pump body.

5. Pure Iron
When all the impurities in iron are removed, theoretically pure iron can be obtained, but in practice it is not possible to produce a material with a purity of 100 per cent. However, there is still the term pure iron, and the iron content of this pure iron is 99.90% ~ 99.95%. It can be used as a special industrial material.

Application Fields

Steel is used in almost every industry, from large aircraft, ships and skyscrapers to small staples and pencil sharpeners. The following is a list of some common areas of application for sheet metal parts made of steel.

1.Automobile manufacturing

Body parts: Special sheet metal parts are widely used in the construction of car bodies, such as doors, bonnets, boot lids and roofs. These parts are formed into curved surfaces and shapes through the stamping process to meet the appearance and performance needs of automobiles.

Chassis Structure: The chassis is the backbone of the vehicle, and many chassis components such as cross members, longitudinal beams, and suspension systems are made of iron sheet metal. These components need to withstand the weight of the vehicle and various forces during driving, and require materials with sufficient strength and rigidity.

Interior parts: Although some interior parts are made of plastic and other materials, iron sheet metal parts are still used in parts such as seat frames, armrests, and pull handles.

2.Home Appliance Manufacturing

Shell Manufacturing: The shells of home appliances such as refrigerators, washing machines, air conditioners, etc. are often made of sheet metal. These shells are not only required to be aesthetically pleasing, but also need a certain degree of strength and durability to protect the internal components from damage.

Internal structure: In addition to the shell, the internal structure of home appliances may also contain iron sheet metal parts, such as brackets, partitions, air ducts, etc. These parts are used to support and fix the internal components. These parts are used to support and secure the internal components of the company to ensure the normal operation of the product.

3.Building Components                                 

Steel buildings: In steel buildings, ferrous sheet metal parts are used in large quantities for the manufacture of beams, columns, wall panels and other components. These components are welded or bolted together to form a stable structural system that carries the weight and load of the building.

Roofs and Walls: The roofs and walls of some buildings may also be decorated or protected with sheet metal parts. These sheet metal parts are anti-corrosive, fire-resistant, weather-resistant, etc., which can extend the service life of the building.

4.Mechanical Equipment

Shell Manufacturing: The shells of mechanical equipment are often manufactured using sheet metal parts made of iron. These shells not only play a role in protecting the internal components, but also have a certain degree of dustproof, waterproof, radiation and other functions.

Brackets and bases: Brackets and bases for mechanical equipment also need to be made of strong and durable materials, and iron sheet metal parts are preferred for their good strength and rigidity. These parts are used to support and fix the mechanical equipment to ensure its stable operation.

In A Word

The use of steel has a long history, from ancient time 2 thousand years ago to now. The technology and steel products have been improved through the time.

In order to meet the needs of a variety of uses, people continue to carry out research and improvement, and finally produced kinds of steel, which has a wide range of uses, from high buildings, bridges, machine tools, aircraft, ships, automobiles, trains, as small as knives, frying pots. In the future, steel will continue to support all aspects of human life.