Steel is used in so many applications, from construction and transportation to residential tools and appliances. Steel comes in a variety of forms, and knowing which one to use is critical because using the wrong one can result in poor quality or performance.
Different types of steel have varying properties like strength, hardness, toughness, machinability, weldability, corrosion resistance and conductivity. Knowing the application of your steel will help you choose the right type of steel.
Once you have the right type of steel for your purpose, you will certainly reap the benefits. Before you reach the fabrication design and prototyping stage, identifying which steel is best for your project will determine what processes will be effective.
If you’re not sure what type of steel is best for your needs, speaking to an experienced metal fabrication company can provide you with expert guidance. However, to get you started, we’ve created this article covering the basic types of steel on the market.
Here is our useful guide to help you better understand the different types of steel and decide which one you need to use.
What Is Steel?
Steel is an iron alloy that is one of the most universally used things in construction around the world. Primarily, a metal can be called steel if it has iron and carbon as its foundation, however different elemental make-ups will affect what type of steel it becomes, and how it’s commonly used.
Steel is produced in billions of tonnes at a time. It is an extremely important type of metal thanks to its wide range of applications. Its primary uses range from the infrastructure industry to product manufacturing of appliances, medical equipment, and even artworks like outdoor sculptures.
There are various types of steel, but the most common ones are carbon steel, stainless steel, alloy steel, and tool steel. The properties of steel changes depending on its composition—number and variety of impurities—and how it is heated and cooled. It is important to know which steel is used to manufacture something because certain properties are not ideal for every application.
Depending on the steel’s composition, it may be suitable or unsuitable for different fabrication methods (such as laser cutting vs plasma cutting), require different machinery (like CO2 vs fibre laser cutters) or require different types of welding to work with successfully.
For you to understand the different types of steel better,you should know the common mechanical properties of steel.
- Yield strength refers to steel’s ability to be deformed, bent, or warped. High yield strength means it can withstand or resist deformation, bending, or warping.
- Tensile strength is how much force is needed to break steel.
- Hardness refers to the ability to withstand or resist friction and abrasion.
- Toughness is the ability to absorb or resist stress without breaking or fracturing.
- Machinability refers to the ease of cutting, drilling, grinding, or processing steel using a machine. This is inversely proportional to hardness as, when hardness increases, machinability decreases.
- Weldability refers to the ease of welding or joining metal together using heat.
- Ductility or Elongation is the threshold of the steel in terms of stretching and/or compressing. How much can it be stretched or compressed without breaking?
These are just a few terms to keep in mind when selecting steel for your specific application. Remember that the pros of a type of steel might actually be cons for the use you intend for the steel. Always consider your goal for the material in mind.
What Are The 4 Main Types Of Steel?
The four main types of steel are carbon steel, stainless steel, alloy steel and tool steel. The difference between these types of steel is their elemental make-up, and the difference in this make-up allows them to serve different roles across multiple industries.
Carbon steel is the most commonly used steel in the world. It refers to steel that mixes iron with less than 2% carbon. The higher the carbon, the greater the steel’s strength and hardness, but also its brittleness. Higher carbon also means lower ductility, as well as more difficult weldability and machinability.
Carbon steel has three main types.
- Low Carbon Steel or Mild Steel has up to 0.3% carbon. It is characterised by high ductility and low tensile strength.
- Medium Carbon Steel has 0.31% to 0.6% carbon. It also has .060% to 1.65% manganese, which increases the steel’s tensile strength and hardness. Therefore, it’s relatively tougher to weld, cut, and form into shape. It also has lower ductility compared to low carbon steel.
- High Carbon Steel or Carbon Tool Steel has 0.61% to 1.5% carbon. It is hard, brittle, and difficult to cut and weld.
Some further categorise carbon steel into Extra Low Carbon Steel, which contains 0.05% to 0.015% carbon, and Ultra-Low Carbon Steel, which has less than 0.015% carbon.
Pros Of Carbon Steel
Carbon steel is a staple in the construction industry for the many benefits it provides, including:
- High tensile strength
- Usability in small-scale and large-scale construction or building projects
- Cost-effectiveness, particularly low carbon steel, because of the abundance of iron and carbon
- Wear resistance, particularly medium carbon steel
Cons Of Carbon Steel
Carbon steel is not without its faults, and does have associated negatives such as:
- The high yield strength, making it tough to bend or mould
- A higher susceptibility to rust and corrosion relative to other types of steel, so it’s quite high maintenance in the cosmetic department
- Increased cost due to higher maintenance
- In terms of aesthetics, carbon steel needs to be painted on or powder-coated immediately after polishing for its look to be kept
Carbon Steel Fabrication
Carbon steel is suitable for laser cutting and can be folded or bended with CNC machines, and can be welded making it universally steel. Because different types of carbon steel have varying degrees of ductility, weldability, and tensile strength, it can be found in a variety of industries, such as railway tracks and gears in machinery.
Carbon steel with a low carbon content is easily weldable, and can also be laser cut or plasma cut. However, medium and high carbon steel are not as easy, and they are more prone to weld cracking. Be mindful of the cooling rate of the steel as well, since high cooling rates make your weld more likely to crack. For higher-carbon content steel, you’ll need additional preheating and post-heating treatments or special welding filler metals to be successful, making this a specialised welding process.
The higher the carbon content, the more difficult it is to bend, form, and roll the steel. However, it is not impossible. There are companies that can bend, form, and roll carbon steel into your desired form.
Similarly, a high carbon content also makes it difficult for the steel to be laser cut, but it is still possible to do so. Consult with your local laser cutting provider to find out if they’re able to cut carbon steel for you.
Applications Of Carbon Steel
Carbon steel has a wide range of applications, as it accounts for 90% of global steel production. It’s common across all industries, including infrastructure, construction and defence industries.
Low carbon or mild steel are often used as structural beams, railroad tracks, vehicle frames, chains, rivets, metal sheets, boxes, pipes, wires, cases, gears, etc.
Medium carbon steel can be found in structures like bridges, houses, buildings and skyscrapers, etc.
High carbon steel is used in tough materials like brick nails, trencher blades, high-strength wires, springs, and edged tools like kitchen knives.
Stainless steel is metal with alloying components like chromium, nickel, or molybdenum. Its most distinguishing feature is that it contains at least 10% chromium, which allows it to “heal over” cuts or corrosion while preventing oxidation or rusting.
Its chromium content can get as high as 30%, and the higher the chromium content in the stainless steel, the better the corrosion resistance.
Stainless steel is magnetic and has poor electrical conductivity (particularly martensitic and ferritic stainless steel). Its nickel content, meanwhile, makes it pliable.
Stainless steel has three main types.
- Austenitic Stainless Steel contains 16%-26% chromium, about 35% nickel, and 0.8% carbon. With its high chromium content, it has the best corrosion resistance. It is not magnetic, and it cannot be hardened using heat treatment.
- Ferritic Stainless Steel has 12-17% chromium, trace amounts of nickel along with other alloying elements (e.g., molybdenum, aluminium, titanium), and approximately 0.1% carbon. Compared to other types of steel, ferritic stainless steel still has good corrosion resistance because of its chromium content. Its hardness, toughness, and strength are high. It is magnetic and cannot be hardened using heat treatment, but its strength can be improved through a process called cold working. This is less expensive compared to other types of steel.
- Martensitic Stainless Steel contains about 11%-17% chromium, less than 0.4% nickel, and about 1.2% carbon. It is tough, magnetic, and can be hardened using heat treatment.
Another type of stainless steel is Duplex Stainless Steel or Duplex Alloy, which is a combination of ferritic and austenitic stainless steel. It can, of course, resist corrosion. It lends itself to welding and does not have strong magnetic properties.
Precipitation Hardening Stainless Steel is also another type. It is made up of 17% chromium, 4% nickel, and trace metals like aluminium, copper, and niobium. It only has moderate corrosion resistance, but it can be moulded well.
Pros Of Stainless Steel
Stainless steel is potentially one of the most common types of steel, and it’s easy to see why. The massive list of benefits associated with stainless steel includes:
- Corrosion and rust resistance, up to 200 times more than mild steel, so it can be used in outdoor or wet environments (to a degree)
- More ductile than carbon steel
- Less brittle than carbon steel
- Has a very high melting point, making it invaluable in machine-building and for construction
- Has a very high pressure point, making it useful for manufacturing storage containers
- Low maintenance, compared to carbon steel, and easy to clean because it does not stain much
- Lends itself to steam-cleaning and sterilising
- Highly durable
- Can be sanded and polished and is more flexible in terms of appearance and aesthetic, compared to other types of steel
- Can have various finishes (e.g., glossy or shiny, matte, mirror)
- Can hold text and designs (making it one of the best materials for plaques, vehicle parts with serial numbers, and metal artworks)
- Can be coloured
Cons Of Stainless Steel
Even though it’s universally recognised as one of the most versatile steels, stainless steel does have negative aspects, such as:
- More expensive than other types of steel
- Weaker wear resistance compared to carbon steel
- Suffers from chlorine-induced corrosion
- Difficult to use in welding
- Fingerprints and smudges show on stainless steel
Stainless steel can be fabricated in many ways, making it one of the most common and versatile metals for fabrication. The most common industrial fabrication methods for stainless steel include welding, CNC bending and folding, and laser cutting. It is also suitable for plasma cutting as a conductive metal. Stainless steel can also be moulded or cast into plates, tubing, bars, channels, and wire.
Aesthetics-wise, stainless steel can undergo brushing, polishing, and even get a satin, matte, brushed, reflective or mirror, bead blast, or heat-coloured finish. Stainless steel can be laser engraved and etched for domestic or manufacturing applications—like adding a company name, house number, bar codes, or serial number for traceability and even etching designs or logos.
Applications Of Stainless Steel
Stainless steel is also very common in the market as its corrosion-resistant property makes it relatively low maintenance.
Culinary Uses – Common applications of austenitic stainless steel include piping, cutting tools, kitchen utensils (e.g., knives), food processing, and commercial kitchen equipment.
Automotive Parts – Ferritic stainless steel is usually used in automotive parts too.
Medical Supplies – Martensitic stainless steel is used in medical equipment (e.g., dental tools, surgical equipment), blades, cutlery, and cutting tools (e.g., knives, pliers).
Industrial Containers and Storage – Duplex stainless steel or Duplex alloy are well-suited for hazardous construction material storage and building applications. Precipitation Hardening Stainless Steel lends itself to engine components and nuclear waste casks.
Alloy steel is carbon mixed with several alloying elements like manganese, nickel, copper, chromium, aluminium, silicon, and/or titanium from 1% to 50%. Although some people confuse alloy steel with carbon steel, the two are not the same.
It is the amount and variety of alloying elements that make the properties of alloy steel different from carbon steel. The mix of alloys determines the steel’s strength, ductility, machinability, weldability, and corrosion resistance.
In terms of hardenability, alloy steel can either be carburising or through-hardening. Carburising steel mostly hardens near the surface, while through-hardening hardens even until the core.
Depending on the ratio of the alloys, alloy steel can either be Low-Alloy Steel or High-Alloy Steel
- Low-Alloy Steel has 8% (weight) or fewer non-iron elements
- High-Alloy Steel has over 8% (weight) non-iron elements
Stainless steel is sometimes considered high-alloy steel as it has chromium as an alloying element at over 8%. Other types of steel under high-alloy steel are ultrahigh-strength nickel-cobalt steel and maraging steel.
Here is a rough guide on how some alloying elements affect the properties of your alloy steel.
|Nickel||2-5% nickel content increases toughness12-20% nickel content increases corrosion resistance|
|Manganese||0.25%-0.4% manganese content with a bit of sulphur can lessen brittlenessOver 1% will increase hardenability|
|Silicon||0.2-0.7% silicon content increases hardenability and strength2% silicon content increases yield strengthHigh percentages will also give magnetic properties to the alloy steel|
|Chromium||0.5-2% chromium content increases hardenability4-18% chromium content increases corrosion resistance|
|Boron||0.001-0.003% boron content increases hardenability|
|Copper||0.1-0.4% copper content increases corrosion resistance|
Pros Of Alloy Steel
The advantages of alloy steel include:
- Economical or cost-effective
- Widely available
- Easy to process
- Has higher tensile strength than stainless steel
- Has a high strength-to-weight ratio, which means it’s relatively light given its strength and ability to withstand pressure.
- Responsive to heat and mechanical treatments as opposed to carbon steel
- Versatile and can have varying properties
- High-alloy steel, in particular, has high hardness, toughness, and corrosion resistance
- Maraging steel, in particular, has high tensile strength and high fracture toughness
Cons Of Alloy Steel
The disadvantages of alloy steel include:
- Relatively lower machinability, weldability, and formability compared to other types of steel
- High-alloy steel is very expensive to manufacture and fabricate
- Can be difficult to get the right mix of alloys to match the properties you desire
Alloy Steel Fabrication
Once alloy steel is made, it can be rolled or moulded into sheets, plates, bars (round, square, flat, hexagon), tubes, rods, coils, and wires. It lends itself to welding, folding, bending, and even laser etching and engraving.
As long as you have the right type of alloy steel, you can fabricate it whichever way you want. For instance, if you’re using high-alloy steel (particularly stainless steel), then you can laser engrave or colour it.
Applications Of Alloy Steel
Low-alloy steel is used in construction equipment, pipelines, ships, pressure vessels, oil drilling platforms, structural components, and even in military vehicles.
High-alloy steel can be used in structural components, automotive parts, aircraft (helicopter, landing gear, rocket motor cases, slat tracks, undercarriages), power-generating equipment, and chemical processing equipment. Stainless steel falls under high-alloy steel, so any applications of stainless steel can also be seen as a benefit of high-alloy steel.
This range of applications makes alloy steel a common metal in defence applications, as well as a full range of heavy industrial uses.
Other applications, depending on the mix of elements, can be found in shipping containers, mining equipment, off-shore applications like the pipes for oil and gas drilling, bearings, railways and road construction, architecture, automotive, appliances, cookware, cutlery, countertops, and even art. Because of the range and versatility of alloy steel, it’s everywhere.
Tool steel refers to a variety of steel mixed with alloying elements like vanadium, molybdenum, tungsten, and cobalt. Its distinguishing features are hardness and abrasion resistance, as well as good durability and heat resistance. Thus, tool steel is usually used in high-impact applications and environments.
There are seven main types of tool steel.
- Water-Hardening Tool Steel (W-grade steel). This is essentially high carbon plain carbon steel and commonly manifests itself in chisels, files, lathes, drills, and razor blades.
- Shock-Resisting Tool Steel (S-grade steel). This can resist shock and deal with both low and high temperatures, as seen in impact hammers on nail guns and jackhammer bits.
- Plastic Mould Steels (P-grade steel). This is usually used as moulds for plastic and zinc die casting.
- Cold Work Tool Steels consist of oil-hardening (O), air-hardening (A), and high-carbon high-chromium (D) steels. O-grade tool steel, which hardens from oil-quenching, has great machinability, so it is used for gauges, taps, reamers, stamping dies, and blanking and forging dies. A-grade tool steel, which is hardened by air, is used in dies (trimming, thread rolling, injection moulding), forming tools, and blanking and forming punches that require good stability with moderate wear resistance. D-grade tool steel, which is oil or air-hardened, is used for master gauges, shear blades, blanking and piercing dies, drawing dies (bars, tubes, wires), etc.
- Hot Work Tool Steel (H-grade tool steel). This type of steel has high hot yield strength, so it is used for die casting of aluminium and copper, forging, hot piercing, hot stamping, hot pressing, etc.
- High Speed Tool Steel. With properties like high hardness, strength, wear resistance, and reasonable toughness, this tool steel is used particularly for high-speed metal cutting.
- Special Purpose Tools Steel. This includes Low-Alloy types (L) and Carbon-Tungsten types (F). L-grade tool steel has high wear resistance and toughness, so it is used for bearings, clutch plates, cams, rollers, wrenches, etc. Meanwhile, F-grade tool steel has high wear resistance but for low-impact applications, and it can be seen in broaches, taps, paper-cutting knives, wire-drawing dies, plug gauges, reamers, etc.
Pros Of Tool Steel
The advantages of tool steel include:
- Very durable
- Physically hard
- Has good abrasion resistance
- High heat resistance
- Resilient, for high-impact applications
- W-grade tool steel, in particular, is very cheap
Cons Of Tool Steel
The disadvantages of tool steel include:
- Application is very specific to tools
- Has a lot of varieties, so it requires proper knowledge to be fabricated with good quality
Tool Steel Fabrication
Tool steel is mainly used to form other metals in a manufacturing context. This type of metal can be cut, welded and bent and folded through a CNC fabricator to form it into plates, sheets, coils, strips, rods (drill rod) and pipes, bars (flat, round, square, ground flat stock, ground square stock), rails, wires, angles, and other shapes.
Tool steel can also be deep laser-engraved.
Applications Of Tool Steel
Tool steel can be used in dies (e.g. forging dies, drawing dies, wire-drawing dies, plastic injection moulding dies, zinc die casting), forging, blades and tools (e.g., wrenches, knives, cutting tools, drills, files, razor blades, hammers and sledges, woodworking tools), punches, bar feed guides, and many more.
The seven types of tool steel (water-hardening, shock-resisting, plastic mould, cold work, hot work, high speed, and special purpose) lend themselves to a variety of uses. This includes the metal fabrication and manufacturing industries, as well as agricultural tools and equipment.
Other Types Of Steel
Galvanised steel is steel or iron coated with zinc. The zinc protects the steel from corrosion or rusting. It is durable and has reasonable strength and formability. It is commonly used in automotive, construction, solar, and agricultural applications.
Some pros of galvanised steel are its low cost, and its relatively long lifespan. Because of its zinc coating, the zinc corrodes first before it eats away at the steel underneath. Maintenance costs also won’t be as high as buying new steel.
Colorbond steel is a well-known brand of steel that is commonly used around Australia for fencing and roofing. It is essentially galvanised steel treated with anti-corrosion and weather-resistant paint for extra protection, so it is perfect for outdoor use.
Made in Australia, Colorbond steel is durable, lightweight, and is even designed to reduce cooling costs. It is made for the Australian climate and also lends itself to some artistry with over 20 colours to choose from. Colorbond steel can be laser cut depending on the intricacy of the intended design.
Weathering Steel (Corten)
Weathering steel, trade name Corten steel, is atmospheric corrosion resistant steel made in the USA. It is low alloy steel with high strength. Usually used outdoors, weathering steel develops rust or patina when it’s exposed to elements like water, moisture, and air. The patina then develops a barrier that prevents further corrosion to the steel underneath.
Weathering steel is very low maintenance, especially if you don’t paint over it or you don’t plan to maintain it with paint, and it can be used long-term.
Things To Consider When Choosing Steel
There are a variety of things to consider when choosing a type of steel for your next project, including:
Purpose – What will you use it for? Does it need to have high hardness, weldability, and/or strength? Does it need to be heat-resistant, shock-resistant, and/or weather-resistant?
Environment – Will it withstand the environment you will put it in? Or does it need to withstand harsh weather or a wet environment?
Availability, cost, and maintenance – Will I get enough supply of this type of steel, or will I need to import when there’s a shortage? Is it cost-effective, or will I be spending too much to maintain it in the long run?
Most of these factors overlap, so use this guide wisely when choosing steel. Some people prioritise strength, ductility, and toughness when picking steel, and rightfully so since they’re related to the capacity to perform your needs and maintenance. That said, purpose, environment, and availability, cost, and maintenance should trump those mechanical properties because nobody wants good steel to be wasted on the wrong purpose.
For the very best advice, speak to an experienced metal fabrication company – they can advise which type of steel is best for the results you need.
What Type Of Steel Takes The Longest To Rust?
Galvanised steel usually takes the longest to rust or corrode. This is because the zinc coating protects the steel from corrosion.
Colorbond steel is also in an excellent position for this since it is essentially galvanised steel with an extra coating of weather-resistant and anti-corrosion paint.
Which Steel Is Safe For Planting?
You can use either galvanised or stainless steel boxes for planting. But the best and safest choice is galvanised steel. Galvanised steel can withstand the wear and tear of the soil and water. Corten steel is also a popular choice for garden planters.
Which Type Of Steel Is Easiest To Maintain?
Stainless steel is the easiest to maintain. Though fingerprints and smudges show on stainless steel, they can easily be wiped. Because it is also corrosion-resistant, you don’t have to worry about scrubbing away rust. However, steel metal art outdoors will still need protective coating and maintenance to stay in good condition.
Which Types Of Steel Can Be Painted?
The types of steel that can be painted are carbon steel, stainless steel, alloy steel, galvanised steel, and even weathering steel. It’s really the priming and the type of paint that you should think about when painting steel.
What Is The Most Common Type Of Steel?
Carbon steel is the most common type of steel, accounting for 90% of steel production in the world. It is used in construction and infrastructures, automotive and transportation, and many more key industries.
How Is Steel Graded?
There are different organisations that grade steel, but essentially, it is graded by composition (the variety of metal alloys mixed into iron and carbon), manufacturing or fabrication (how it was treated, heated, and cooled), and properties (strength, hardness, toughness, machinability, ductility, weldability, and others).
This article is published in good faith and for general informational purposes only. Kanyana Engineering does not make any warranties about the ongoing completeness and reliability of this information. Always seek specific advice on your metal fabrication project to ensure all variables are taken into consideration.
Graham Dawe is the Managing Director and Works Manager of Kanyana Engineering. With decades of experience in the metal fabrication industry, he is dedicated to keeping Kanyana at the forefront of the sector’s technological growth. Looking beyond the process itself to holistic, integrated CAD, CAM and MRP solutions, Graham believes Australian manufacturing has an enduring place on the global stage. In Kanyana Engineering’s state-of-the-art workshop in Mandurah, WA, Graham delivers an exceptional standard of work for commercial, industrial and government clients alike.