Iron is the most abundantly available mineral spread throughout the earth’s core and mantle, though it’s extremely soft in its pure form and needs to be oxidized into iron oxide. The poor strength and durability of this form greatly obstruct the use of iron. To enhance these properties, up to 2% of carbon is added to pure iron, producing a highly durable and hard substance called steel.
Owing to its high tensile strength and solidity, steel is used to fabricate everything from sewing needles to oil tankers, as well as the tools required to produce them. Yet, other metal types are often added to steel to incorporate different qualities depending on the intended use.
These metallic additions have produced 3,500 different variations of steel up till now, each carrying different structural, chemical, and physical features and properties. Even more startling is the fact that more than 75% of these variations were introduced in the last two decades to cater to rapidly developing industrial demands.
Table of Contents
- Carbon Steel
- High Carbon Steel
- Medium Carbon Steel
- Low Carbon Steel
- Alloy Steel
- Tungsten Steel
- Nickel Steel
- Manganese Steel
- Vanadium Steel
- Chromium Steel
- Chromium-Vanadium Steel
- Silicon Steel
- Molybdenum Steel
- Cobalt Steel
- Aluminum Steel
- Tool Steel
- Shock Resistant Tool Steel
- Special-Purpose Tool Steel
- Hot-Work Tool Steel
- Stainless Steel
Let’s explore the most frequently used types of steel, their distinctive properties, and uses:
Most of the steel around the globe is some form of carbon steel. It comprises of iron, carbon and varying specific amounts of other alloying elements. As the main alloying element of carbon steels, carbon accounts for around 90% of all steel production. It helps create a stronger and a lot more rigid metal. This is because the atoms present in carbon allow it to travel through the iron’s crystal lattice, slightly distorting the lattice and filling the gaps between the metallic atoms.
Given this characteristic, the resultant carbon steel products are extremely hard. What determines this strength is the amount of carbon present, further classifying it into three categories:
High Carbon Steel
High carbon steel typically contains around 0.61% to 1.5% carbon content, resulting in strong, brittle, and hard steel. To improve its wear resistance, it is taken through appropriate heat treatment. Besides being used for high strength wires and springs, it is a useful material for producing shock-absorbing machinery.
Medium Carbon Steel
This variation incorporates carbon content of 0.31% to 0.6%, resulting in mildly ductile steel with more tensile strength than low carbon steel. To harden it, it is often treated with tempering, a form of heat treatment. Because it is highly malleable and can be molded into a variety of shapes and sizes, this type is the most commonly used among the three. From skyscrapers to fences, to bridges and homes, you’ll see it used everywhere.
Low Carbon Steel
Low carbon steel contains up to 0.3% carbon. While it offers high malleability and ductility, low carbon steel is characterized by low tensile strength, which can certainly be improved through the process of cold-rolling. This involves rolling the steel between two polished rollers under high-pressure conditions. Among its most common uses include the production of metal sheets, boxes, pipes, chains, wires, cases, rivets, vehicle frames, etc.
Alloy steel is composed of varying amounts of different metals besides iron. These additions help manipulate the properties of steel to serve specific applications. Metals such as aluminum, nickel, silicon, chromium, manganese, titanium, and copper are used in some capacity. The use of these metals results in characteristics not found in carbon steel. Desired changes occur in the steel’s strength, formability, corrosion resistance, ductility, and hardenability.
Generally more responsive to different sort of treatments, alloy steel is used in more specialized industries such as appliances, shipbuilding, and the automotive industry. It may come in stronger or more tactile forms, those with high resistance to rust, or those that are more suitable for welding.
Alloy steel is often used to manufacture pipelines, auto parts, power generators, transformers, and electric motors.
Depending upon the combination of alloying elements, alloy steels encompass numerous different variations. We’ve put together the most widely used types:
Tungsten, also known as wolfram, is basically a dull silver metal that boasts the highest melting point among all metal types in their purest form. What makes it stand out from other metal types is its strength and ability to withstand high temperatures. Owing to these characteristics, different steel alloys make use of this metal to enhance resistance to corrosion and wear.
Besides this, rocket engine nozzles make use of tungsten steel to achieve high heat resistance. If combined with cobalt, nickel, and iron, tungsten steel can be used to produce turbine blades for many types of aircraft. Besides, many other machines and tools require high heat resistance, and thus, make use of tungsten steel.
Source: The balance
Nickel steel alloy is among the most commonly used steel alloy around the globe. Besides a high nickel content of around 3.5%, it comprises of approximately 0.35% carbon content. Its specialty is that adding nickel strengthens structural steel without a proportionate decrease in ductility. This increase in toughness helps resist fractures that may be caused by high impacts, shocks, and loads.
Moreover, at the time of quenching, nickel decreases the value of distortion in steel. Nickel steel offers incredible responsiveness to heat treatment as the addition of nickel lowers the steel’s temperature, making it ideal for heat treatment.
Source: Bright hub engineering
Manganese steel is a work hardening steel that is made up of 11 to 14% manganese content. Due to its excellent work hardening characteristics and wear resistance, manganese steel is used in manufacturing complex railway tracks. Other contemporary applications include shovel buckets, shot blast cabinets, scrapers, anti-drill security plates, etc.
Source: West Yorkshire Steel
Vanadium steel is known for its corrosion-resistant properties as well as the ability to absorb shocks. Besides being used for chemical-carrying pipes and tubes, vanadium steel is used in the form of a thin layer to bond titanium to steel for aerospace applications. As little as 1% vanadium and chromium are sufficient to achieve shock and vibration resistance, making it ideal for automobile applications.
The addition of chromium lowers the critical cooling rate and increases the scaling resistance, wear resistance, and high-temperature strength of steel. It is primarily used to increase corrosion resistance. Featuring high elasticity and tensile strength, chromium steel is often used to manufacture machine and auto parts, rock crushers and safes.
Chromium-vanadium steel makes use of both chromium and vanadium, combining the features of each. Featuring extremely high tensile strength, the steel is can be easily cut but is not brittle. Common uses include gears, axles, connecting rods, vehicular frames, and so on.
When it comes to magnetic force, silicon steel is the most significant material used today. While small quantities of silicon steel are used in pulse transformers and small relays, applications like large motors and generators utilize tons of silicon steel. Among its properties, saturation reduction, resistivity, magnetostriction, and magneto-crystalline anisotropy are highly sought out. With a mere 1 to 2% addition of silicon, the steel is most widely used to produce permanent magnets.
Source: Total materia
As a valuable alloying agent for steels, molybdenum helps improve the steel’s toughness, weldability, as well as its corrosion resistance. This makes it ideal for use in structural steels, and therefore, they are widely used in marine environment applications. Oil and gas pipelines and ball bearings also make use of molybdenum steel.
Cobalt alloys offer tremendous corrosion resistance, wear resistance, high-temperature strength, and magnetic properties. Some tougher cobalt applications include gas-turbine vanes and buckets. Yet, this type of steel is more commonly used to make cutting tools.
Source: Science direct
The addition of aluminum helps incorporate the ability to reflect heat. Comprising of a density of around one-third of that of steel, it is used in applications where low weight and high strength are essential. Aluminum steels are thus widely used to manufacture exhaust systems of motorbikes and cars. Besides the automotive industry, aluminum steel is diversely used in energy generation, architecture, food preparation, packaging, electrical transmission applications, etc.
Tool steels are the type of steels used for producing different sort of tools used for a wide range of purposes, including impact tools, cutting tools such as knifemaking tool, and others. They are made up of metal alloys such as tungsten, cobalt, molybdenum, and vanadium in varying amounts. Not only are they hard and durable, but also highly resistant to heat.
Depending on the type of tool to be produced, the quality of tool steel differs, resulting in numerous variants within the tool steel category:
Shock Resistant Tool Steel
As the name suggests, this tool steel variant is designed to offer high resistance to shocks at varying temperature levels. Comprising of low contents of carbon, silicon, and molybdenum, it is abrasive and moderately tough. This steel is mostly used to manufacture tools such as screwdrivers, punches, chisels, and tools used in riveting.
Special-Purpose Tool Steel
This tool steel is specifically designed to achieve moderate toughness and malleability, using a low alloy class of steel. They are often used for producing wrenches, arbors, and taps.
Hot-Work Tool Steel
Hot-work tool steel is used to produce tools that require high resistance to heat for prolonged time periods, such as those utilized in forging, extrusion, punching, casting, and hot-shearing blades.
Water-Hardening Tool Steel
As the cheapest type, water-hardening tool steel is the most widely used tool steel in the production of tools. To incorporate hardness into the objects or tools, this steel is water quenched. Featuring high resistance to surface wear, this steel is often used to make files, cutters, hammers, blades and similar items.
High-Speed Tool Steel
High-speed tool steel is composed of tungsten, molybdenum, and vanadium steel alloys. These components are hard and retain their hardness when exposed to high temperatures, helping produce steel that’s perfect for high-speed machinery such as drills, reamers, saws, punches, taps, etc.
Cold-Work Tool Steel
This tool steel variant incorporates a high chromium content to achieve low distortion property while hardening, which may be done through air or oil. This feature means that the tools produced do not crack easily. As highly sturdy steel, cold-work tool steel is ideal for making knife blades, stamping dies, coining tools, etc.
Mold steel makes use of carbon steels to make injection and compression molds for plastics. Plus, another common application is zinc die casting.
Source: Science struck
While stainless steel is made of several metal alloys, chromium serves as the primary element, constituting 10 to 20% of the total steel composition. Previously known as ‘Rustless’ steel, stainless steel is highly popular due to its appearance and its high resistance to rust. Precisely, it is approximately 200 times more resistant to rusting than other steel types, particularly when the amount of chromium is more than 11%.
Owing to its ability of high corrosion resistance, stainless steel is the most expensive type of steel. As a highly durable type, stainless steels are capable of withstanding wear and tear that is bound to happen as a result of everyday use. To further enhance its resistance to scratches and corrosion, the invisible chromium layer serves to prevent oxidation. Other metal components that make up stainless steel include molybdenum and nickel.
Based on the application, the sizes and grades of stainless steel may be different, and they may come in the form of sheets, bars, tubes, plates, and wires. Based on the crystalline structure and mechanical properties of stainless steel, it can be further categorized into various types:
Ferritic Stainless Steel
Ferritic stainless steel contains about 12-17% chromium, up to 0.1% carbon, trace amounts of nickel and other alloy metals in small quantities such as aluminum, molybdenum, and titanium. While ferritic steels are tough, strong, and magnetic, they can be further strengthened by cold working. However, they aren’t responsive to heat treatment, which means they can’t be hardened through this technique.
Austenitic Stainless Steel
Austenitic steel is much high in chromium content than its stainless steel counterparts. The chromium content in this type of steel can be as high as 18%, while other elements include nickel, constituting 8%, and carbon at 0.8%. Even though austenitic steel is unresponsive to heat treatments, it is popular for its non-magnetic properties, making this steel one of the most widely used steels worldwide. Some common uses include the manufacturing of pipes, food processing equipment, and kitchen utensils.
Martensitic Stainless Steel
Comprising of 11 to 17% chromium, martensitic steel contains approximately 1.2% carbon and less than 0.4% nickel. Martensitic steels are not only responsive to heat treatments but also encompass magnetic properties. Dental and surgical instruments, knives, blades, and other cutting tools make use of martensitic stainless steel.
Duplex Stainless Steel
Duplex steel is simply a combination of ferritic and austenitic steels, resulting in steel that’s much stronger than both individually. It is not only weldable but also corrosion-resistant. Yet, it’s not strong magnetically.
Precipitation Hardening Stainless Steel
This steel is made up of 17% chromium and 4% nickel, leading to a hardened steel variety. Additionally, some other metals are also added in varying quantities, including aluminum, copper, and niobium. This type can be molded into different shapes, making them ideal for use in engine components and nuclear waste casks. It also offers moderate corrosion resistance.
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