What is steel what are the main properties of steel

What Are the Types and Properties of Steel?

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Terence Bell is a former writer who has been involved in the rare earth and minor metal industries for over 10 years.

Different types of steel are produced according to the mechanical and physical properties required for their application. Various grading systems are used to distinguish steels based on these properties, which include density, elasticity, melting point, thermal conductivity, strength, and hardness (among others). To make different steels, manufacturers vary the type and quantity of alloy metals, the production process, and the manner in which the steels are worked to produce particular products.

According to the American Iron and Steel Institute (AISI), steels can be broadly categorized into four groups based on their chemical compositions:

Properties of Carbon Steels

Carbon steels are alloys made from a combination of iron and carbon. By varying the percentage of carbon, it is possible to produce steel with a variety of different qualities. In general, the higher the carbon level the stronger and more brittle the steel.

Low carbon steel is sometimes called «wrought iron.» It is easy to work and may be used for decorative products such as fencing or lamp posts. Medium carbon steel is very strong and is often used for large structures such as bridges. High carbon steel is used mainly for wires. The ultra-high carbon steel also called «cast iron» is used for pots and other items. Cast iron is very hard steel, but it is also quite brittle.

Properties of Alloy Steels

Alloy steels are so named because they are made with a small percentage of one or more metals besides iron. The addition of alloys changes the properties of steels. For example, steel made from iron, chromium, and nickel produces stainless steel. The addition of aluminum can make steel more uniform in appearance. Steel with added manganese becomes exceptionally hard and strong.

Properties of Stainless Steels

Stainless steels contain between 10 to 20% chromium, making the steel extremely resistant to corrosion (rusting). When steel contains over 11% chromium, it is about 200 times more resistant to corrosion as steels that do not contain chromium. There are three groups of stainless steels:

Properties of Tool Steels

Tool steels are durable, heat resistant metals containing tungsten, molybdenum, cobalt, and vanadium. They are used, not surprisingly, to make tools such as drills. There are a variety of different types of tools steels, containing varying amounts of different alloy metals.

Properties of Steel | Understanding Material Properties

Every type of steel has unique properties that affect how it performs. When finding a type of steel to specify its important to understand how the material properties will affect all aspects of your project.

Just with most things in life, there are trade offs when selecting a type of steel. This requires having a thorough understanding of the manufacturing, construction or assembly, and use of your product or project prior to selecting ideal steel properties.

Characteristics

Weldability

Weldability is a property of steel that greatly affects how easily it can be used in construction and fabrication. A steels weldability determines how easily a material can be welded. Materials with low weldability are likely to crack due to the local stresses caused from heating at the weld joint. A materials weldability is inversely correlated to the materials hardenability. This is because if a material is hardenable it will tend to harden during the welding process which can increase the brittleness and lead to cracking due to local thermal strain.

There are many different welding methods including Arc (aka stick) Welding, MIG Welding, TIG welding, Flux-Cored Arc Welding, Energy Beam Welding, Friction Welding, and more. Each welding method is used in different scenarios for different types of metals.

To weld steels with low weldability you can a use a heat treatment process which will increase the ductility of the material during the weld making it less susceptible to cracking. You may also need to relieve the residual stresses after the welding through another heat treatment process.

Hardenability

If your design is going to be required for cutting or need substantial wear resistance then the hardenability property of steel should be weighed in your decision.

A materials hardenability determines how easily the material can be hardened by thermal treatment. As hardenability increase, weldability decreases and vise versa. Steel with adequate or high hardenability can have hardness levels specified during the design phase. This is standard practice for tooling, and applications that require surface durability. Since hardness and ductility and inversely related, controlling the hardness of a material allows you to optimize the materials properties.

Hardenability can be affect by alloys, but is also dependent upon carbon content. Tool steel alloys which have exceptional hardenability also have high carbon content. Many steels can also only be surface hardened and not through hardened.

Machineability

If you are going to have to cut or remove material for your design then the machineability property of steel should play a role in your material selection.

Machineability is dependent upon a lot of factors. If a material is too hard it will reduce the tool life and dramatically increase the part costs. If a material is too ductile it can spring back after being cut leading to difficulty meeting tolerances. The most machinable metals are those with lower hardness and moderate ductility. To avoid wearing down tooling quickly, most metals are heat treated to the desired hardness after being machined. 01 Tool steel for instance is machined after being fully annealed to remove any residual stress and improve machinability. Once tool steel is machined it is then heat treated up to the desired hardness.

A materials ability to be work hardened also can reduce the machineability of a part as it deforms and hardens during manufacturing. This can lead to thermal build up in the machined part instead of the metal chips causing thermal distortions making meeting tolerances difficult. If cut rates and speeds aren’t properly adhered to it’s also possible for some metals to work harden to the point that they meet the same hardness as the tool leading to a dangerous tool failure. Metals such as stainless steel and high-temperature alloys are the most prone to work hardening and require extra care during machining.

A machinability rating system has been created which is based on a significant number of factors. The system uses 1212 steel as it’s benchmark 100% rating.

Workability (Bending / Forming)

If your design requires bending steel or if you can benefit from the low cost and high volume of stamping, then the workability property of steel will be critical for your project.

Workability affects how easily a material can be bent or formed. This is commonly done to form sheet metal or even steel plate into various shapes including anything from car panels to very large rolled steel tubes. Metals with high work-ability can be used in stamping without the need for expensive servo presses or can be easily formed into various shapes with tight bending radius’s.

Material properties including hardness and ductility have a large effect on workability. Higher strength metals such as high carbon steel have lower ductility making them far less workable compared to low carbon steel which has high ductility. In order to form metal you have to yield it making metals with a high yielding point and lower ductility less workable as they require more energy to bend and are prone to fracturing during bending. A materials stress strain curve can guide how much a material can be formed prior to failing.

After a material has been worked it will retain residual stresses and have reduced ductility due to work hardening. If needed the material’s residual stresses can be relaxed by annealing the formed metal which removes residual stresses and returns ductility.

Workability can also be increased by heating the metal. This is refereed to as hot workability. As a metal is heated it’s ductility increases and the yield stress decreases which leads to dramatically increased workability. This can be used to hot form higher strength metals that would typically crack if cold formed.

Wear Resistance

If you’re making a cutting edge, a stamping die or something similar then the wear resistance property of steel will be dictate how long your tool can be used prior to failing.

Wear resistance is a materials resistance to surface material loss due to some form of mechanical action such as abrasion, erosion, adhesion, fatigue, or cavitation. Materials such as Diamond and Sapphire have extraordinarily high wear resistance which makes them ideal for use as gem stones that last a lifetime or used in demanding cutting tools. Surface hardness greatly affects the wear resistance of a material. The high surface hardness of a file allows it to wear down other metals of lower hardness without experiencing significant wear itself.

The hardness or wear resistance of metals is affected by the lattice geometry formed by the atoms of the metal. If atoms are able to move or dislocated within this lattice due to irregularities then the hardness of the metal is lower. When dislocations are prevented due to the lattice structure then the hardness of the metal increases delivering improved wear properties. When a metal is heat treated in order to increase the metals hardness the lattice structure is rearranged to form martensite in which the lattice structure is far less prone to slipping.

Corrosion Resistance

Corrosion resistance measures how well a material can withstand damage caused by oxidation or other chemical reactions. Metals have different levels of corrosion resistance.

Metals that are going to be exposed to rain, water, humidity, or anything else that can cause a metal’s surface to oxidize are vulnerable to corrosion damage. To protect against corrosion you can use stainless or galvanized steel, titanium, aluminum, weathering steel, or add and maintain a sealant layer such as paint.

Unless a metal is only exposed to vacuum, after enough time corrosion will occur. This is why corrosion prevention maintenance and monitoring is needed for any critical component. To determine maintenance recommendations you will want to calculate the corrosion rate.

Due to the high cost of stainless steel and aluminum most large scale civil projects today rely on weathering steel or sealants such as paint, or concrete cover to prevent corrosion damage.

While materials such as stainless steel, galvanized steel, weathering steel, titanium, or aluminum are highly corrosion resistant, they are not corrosion proof. Stainless steel, contains a very thin oxide layer which remains passive in the presence of corrosive elements. It is possible for the passive layer to break down exposing localized spots to corrosion. Galvanized steel provides corrosion resistance through a thin layer of zinc coating which bonds with the iron. Should the galvanized layer wear away the steel will become susceptible to corrosion again. Similarly weathering steel, titanium, or aluminum can all be affected by corrosion under certain situations. The best protection from corrosion is monitoring and maintenance.

Properties

Yield Strength (Yield Stress or Point)

The yield strength of a material is the point at which a material begins to undergo a significant increase in the rate of strain in relation to stress. At this point ductile materials such as low carbon steel will begin to undergo significant deformation. An example of this is an overfilled room where the floor begins to deflect far more than what is typical.

Most designs will use yield strength as the design limit as once a material goes past the yield point it’s fatigue life becomes dramatically reduced. Some designs where remaining below the yield point of a material can add significant cost or that only require a limited number of uses may exceed the yield point and allow plastic deformation. To design a component for plastic deformation while meeting required cycle counts you will need to use more advanced analysis techniques such as nonlinear transient FEA which ASR Engineering provides frequently for our clients.

Springs are reliant on a very high yield strength which allows them to remain elastic and spring back to their original position after deforming.

Tensile Strength (Ultimate Stress)

The tensile or ultimate stress of a material is the point at which deflection will continue until fracture unless if the load is reduced. In other words this the amount of stress that will cause a material to fail with enough time. If you approach the tensile strength of a material you will either need to add reinforcement, increase the cross sectional area, switch to a higher strength material, or reduce the load.

Elongation

Elongation measures how much a material will stretch compared to its initial state prior to fracturing. This is communicated as a percentage of total elongation divided by the initial length. For instance a 1 inch long rubber band which can elongate to 2 inches prior to fracturing would have an elongation of 100% at fracture.

The more brittle a material is the less it will elongate prior to fracturing. Materials such as concrete or glass are extremely brittle and fracture or crack if they experience nearly any elongation. Metals however vary significantly in how much they can elongate prior to failure. For instance, alloy and low-carbon steels will typically elongate far more than high-carbon steels.

Hardness

The hardness of a material measures how much it will resist local plastic deformation due to mechanical indentation or abrasion. Hardness is especially important during manufacturing. Materials with high hardness are not able to be machined or formed similarly to materials with lower hardness. Typically metals will be hardened through a heat treatment process after being formed or machined in order to meet required specifications without dramatically increasing manufacturing costs.

While there are multiple hardness scales and types, the most popular for machining is the Rockwell scale. The Rockwell test measures the depth of penetration of an indenter under a large load and compares it to the penetration by a preload. Unlike other hardness tests, the Rockwell test is considered nondestructive. There are three Rockwell hardness scales including HRA, HRB, and HRC which are selected depending on which best represents the materials hardness with HRC representing the hardest materials.

Very hard steel such as chisels, high quality knives, tools, and files have hardness of between HRC 55-66. Meanwhile non-heat treated steel such as A36 doesn’t even use the higher HRC scale and has a hardness of only HRB 67-83 or HRC N/A-2 (HRB 67 doesn’t overlap with the HRC scale).

If you ever wondered why the quality of a knife edge or cutting tool can vary so much it is because of hardness. When you pay for a top quality knife or tool a lot of what you are paying for is the added work and difficulty it takes to acquire the desired hardness which can last without dulling for far longer than low quality competitors.

Types of Steel & Their Properties

Carbon Steel

There are three types of carbon steel. Low-carbon, medium-carbon, and high-carbon steel. Each type varies significantly in properties.

Low Carbon Steel

Medium Carbon Steel

High Carbon Steel

Alloy Steel

Alloy steel was created in order to further improve the properties of steel by combining iron and carbon with other alloys.

Alloy Elements

Stainless Steel

Chromoly Steel

Tool Steel

Spring Steel

Weathering Steel

ASR is a mechanical and aerospace engineering firm that specializes in engineering design and analysis. If you are in need of engineering services then contact us today to speak to one of our experienced engineers for a free quote on your project!

Frequently asked questions about steel

This month we want to answer the most frequently asked questions about Steel, what is steel, what are its properties, etc.

This is a continuation of our Questions Series. Last time we covered commonly asked questions about CNC machining (stay tuned for part 2 of that).

One of the most frequently asked questions about steel; What is steel and how is it made?

When Iron is alloyed with carbon and other elements it is called steel. The resultant alloy has applications as the main component of buildings, infrastructure, tools, ships, automobiles, machines, various appliances, and weapons. The uses are myriad because of steels high tensile strength and relatively low cost.

Who discovered it?

The earliest examples of steel have been discovered in Turkey and date back to 1800BC. The modern production of steel dates back to Sir Henry Bessemer of England who discovered a method of production we high volume and low cost.

What is the difference between Iron and Steel?

Iron is a naturally occurring element found in nature within Iron Ore. Iron is the main component of Steel, which is an alloy of Iron with the main addition of Steel. Steel is stronger than Iron, with better tension and compression properties.

What are the properties of steel?

Which is stronger, Steel or Titanium?

When alloyed with other metals such as aluminum or vanadium, titanium alloy is stronger than many types of steel. In terms of sheer strength, the best titanium alloys beat low to medium grade stainless steels. However, the highest grade of stainless steel is stronger than titanium alloys.

What are the 4 types of steel?

Carbon Steel

Carbon steels contain Iron, Carbon, and other alloying elements such as Manganese, Silicon, and Copper.

Alloy Steel

Alloy steels contain common alloy metals in varying proportions, which makes this type of steel suitable for specific applications.

Stainless Steel

Although stainless steels comprise of several metal alloys, they usually contain 10-20 percent chromium, making it the primary alloying element. Compared to the other forms of steel, stainless steels are approximately 200 times more resistant to rusting, especially the types that contain at least 11 percent chromium. You can read more about stainless steel here.

Tool Steel

This type of steel is alloyed at very high temperatures and often contains hard metals like tungsten, cobalt, molybdenum, and vanadium. Since they are not only heat resistant but also durable, tool steels are often used for cutting and drilling equipment.

What is the strongest grade?

Type 440 – which is a higher grade of cutlery steel which has a higher percentage of carbon, has much better edge retention when properly heat-treated. It can be hardened to approximately Rockwell 58 hardness, making it one of the hardest stainless steels

Why isn’t steel termed as a metal?

One of the most frequently asked questions about steel is why isn’t steel classed as metal? Steel, being an alloy and therefore not a pure element, is not technically a metal but a variation on one instead. It’s partially composed of a metal, iron, but because it also has non-metal carbon in its chemical make-up, it’s not a pure metal.

Which is the most used type?

304 Stainless Steel or Type 304 the most common grade; the classic 18/8 (18% chromium, 8% nickel) stainless steel. Outside of the US, it is commonly known as “A2 stainless steel”, in accordance with ISO 3506 (not to be confused with A2 tool steel)

Is steel a sustainable material?

Steel is a uniquely sustainable material because once it is made it can be used, as steel, forever. Steel is infinitely recycled, so the investment in making steel is never wasted and can be capitalized on by future generations.

Some interesting facts about steel

We hope you enjoyed reading this article and we hope we’ve answered the most frequently asked questions about steel, if you have a question then go ahead and comment and we’ll do our best to answer it.

Properties of Steel

Steel, an alloy of iron, is one of the most versatile and useful metals known to mankind. In this ScienceStruck write-up, we shall learn about some interesting facts and properties of this metal.

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Steel, an alloy of iron, is one of the most versatile and useful metals known to mankind. In this ScienceStruck write-up, we shall learn about some interesting facts and properties of this metal.

Steel is an alloy, consisting mainly of iron, with a carbon content of 0.2% to 2.1% by weight. Though the use of carbon is most common for the production of this metal alloy, other alloying materials like tungsten, chromium and manganese are also used. The proportions and forms in which these elements are used, affect the properties of the steel that is produced – increasing the carbon content for instance, increases its strength. This fact is particularly useful for making different types of steel for different purposes – the strength of steel needed to make a beverage can, is obviously different from the one needed to make railway tracks. There are various types of steel, and the use of this alloy is widespread across industries and infrastructure owing to its many useful properties and characteristics.

Properties of Steel

Tensile Strength

Tensile strength is the amount of stress that a substance can take before becoming structurally deformed. The tensile strength of steel is comparatively high, making it highly resistant to fracture or breakage, which is a key point in its use in infrastructure building.

Ductility

One of the useful mechanical properties of steel, is its ability to change shape on the application of force to it, without resulting in a fracture. This property is known as ductility, which enables it to be used in the making of different shapes and structures ranging from thin wires or large automotive parts and panels.

Malleability

Malleability is closely linked with ductility, and allows steel to be deformed under compression. It allows this alloy to be compressed into sheets of variable thicknesses, often created by hammering or rolling.

Durability

The hardness of this alloy is high, reflecting its ability to resist strain. It is long-lasting and greatly resistant to external wear and tear. Hence it is considered a very durable material.

Conductivity

Steel is a good conductor of heat and electricity. These properties make it good choice for making domestic cookware, as well as electrical wiring.

Luster

One of the physical properties of steel is its attractive outer appearance. It is silvery in color with a shiny, lustrous outer surface.

Rust Resistance

The addition of certain elements, makes some types of steel resistant to rust. Stainless steel for instance contains nickel, molybdenum and chromium which improve its ability to resist rust.

In addition to the above, the following is an indicative properties chart, which illustrates the differences in the properties of different types of steel. Steel is identified by grades, which are defined by specific organizations that set standards for grading. Mild steel and two grades of stainless steel, 304 and 430 are discussed below.

Interesting Facts About Steel

The uses of steel are exhaustive and extensive. With recycling of this alloy, a practice that is commonly followed, its environmental impact is greatly reduced. It has been used for making almost everything, right from the implements for agriculture, to building bridges, railway tracks, cars, engines and airplanes. In fact, you’d be hard pressed to go through a single day without coming across this extremely versatile metal. Over the years the production of steel has increased to its current levels of close to 1300 million tons a year. Whether it’s a knife to cut a fruit, an electric razor, a hair pin, or an entire building, there’s a little bit of steel in everyone’s life!

4 Types of Steel: What Makes Them Different?

Mankind first learned to work with iron some 6,000 years ago, though it wouldn’t be until a few thousand years later when the ultra-common element was applied in its most important role: the production of steel. Steel is used in mechanical and electrical applications, heavy construction equipment, kitchen appliances and tools. With so much variety, it can be confusing to decide the type to use.

Steel is an iron alloy, meaning it’s primarily composed of iron and combined with one or more alloying metals to produce new materials with unique properties. There are four main classifications, but there are also multiple subgroups that serve different purposes. Its properties change depending on the elements iron is combined with as well as the methods used to heat and cool the metal.

Below, we explain the different kinds of steel and the purpose each type serves. We hope this information can help you make decisions about which type to use with clarity and confidence.

What Are the Different Types Of Steel?

Steel is classified by its composition: iron is fused with carbon and any number of other elements to achieve a specific end. The four main types are:

1. Carbon Steel

All steel contains carbon, but carbon steel is unique for a notable absence of other elements in its makeup. Though it only contains 2% carbon or less by weight, its elemental nature makes carbon steel a strong, durable material that is ideal for numerous uses.

Carbon steel is sometimes confused with cast iron, though it must contain less than 2% carbon. Cast iron contains 2% to 3.5% carbon, giving it a rough texture and more brittle nature.

Even though carbon steel is composed of alloyed metals, it doesn’t have alloy classification because of the lack of other alloying elements in its composition. This simplicity contributes to carbon steel’s popularity — it accounts for about 90% of all steel production.

Types Of Carbon Steel

Below the 2% carbon threshold, carbon steel can be grouped into three categories: low, medium, and high carbon. Each type retains the inherent strength of carbon, but its useful purpose will change as the carbon content increases.

Carbon steel’s relative adaptability and low cost make it an ideal choice for a variety of construction projects, both large and small-scale.

2. Stainless Steel

This type is commonly known for its role in manufacturing medical equipment and appliances, but its range of use is far greater than just the gas range in your kitchen. Chromium is the alloy that sets stainless steel apart, lending the material its distinctive luster.

Chromium is more than a purely cosmetic addition, however: the element is oxidation-resistant and will increase the metal’s longevity by preventing it from rusting. Typically, stainless steel has a chromium content of more than 10.5% and sometimes contains up to 30% in certain applications.

Higher chromium content directly translates to a higher gloss when polished and has greater resistance to corrosion. Stainless steel is different from chrome when chromium is electroplated onto another metal to produce a tough, polished coating. The sheen in high-chromium stainless steel applications is less mirror-like due to the addition of other elements.

Types Of Stainless Steel

Kitchen, medical and automotive applications are common, but stainless steel is highly valued for other uses as well. It’s is grouped into four subcategories that each serve a different purpose.

Stainless steel variants, when used in the construction industry, are prized for their corrosion resistance and strength. They’re well-suited for a variety of building applications, as well as storage functions for hazardous construction materials.

3. Alloy Steel

The alloy type is iron fused with one of several other elements, each contributing its own unique attributes to the final product. It’s true that all steels are alloys, but carbon and chromium are specific alloys with names attributed to the type of metal they form.

Alloy steel as a grouping includes a diverse range of alloys with an equally diverse range of properties. Shipping containers use a complex alloy that combines multiple elements to produce a durable and lasting product. Silicon isn’t often thought of as a component of steel, but its magnetic properties make it a perfect component of most large machinery. Aluminum is versatile and used in revolutionary building materials that are both lightweight and extremely durable.

Some of the elements that combine with iron and carbon to produce alloys are also found in tool steels — cobalt, tungsten and molybdenum, for example, are ultra-hard metals that are desired for their impact resistance and cutting abilities.

Types Of Alloy Steel

The varied potential of alloy steel allows for intense customization for specific applications. However, because the secondary elements involved are not always easy to come by like carbon or chromium, certain alloys command a steep price.

Some of the most common alloys include:

Their downright versatility makes alloys a common occurrence in many construction projects. Copper and aluminum alloy varieties are particularly popular for their low weight and heat working properties.

4. Tool Steel

Tool steels are up-front about their business: they’re used to tool manufacturing machinery. Tempering, the process of adding high heat, cooling quickly then heating again, creates tool steel that’s extremely hard and heat-resistant. They’re usually used in high-impact environments and are very abrasive.

Types of Tool Steel

Different types of tools require different types of tool steel in production. Tool steel is used in a variety of ways to best serve the production requirements of a particular tool. Added elements will determine which particular applications that it’s suited for.

These types can be further separated by the industry they’re used in, as well as their hardness and toughness.

What Are the Different Grades of Steel?

Steel is notably complicated due to its many properties and applications. Two comprehensive grading systems have been developed to accurately categorize a particular type, even within subgroups. These systems are standardized across industries so that material integrity can be insured. The two grading systems are:

You can find steel everywhere, materialized in different forms to suit various needs. It’s is an essential component of many building materials, home appliances and even tools used to make other tools. By combining the right elements, an exact steel match is available for almost any application.

Iron and carbon are proven versatile metals that are the building blocks of much of what we see in today’s modern cities, including transportation networks and telecommunications infrastructure. The usage of steel has a long history and will continue far into the future as new ways to combine elements are discovered.