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Steel is one of the most commonly used metals in construction. In 2021, global steel production was around 1.86 billion metric tonnes.
Clearly, the world can’t get enough steel! But what is it about steel that makes it so popular? In this blog, we are going to explore the different properties of steel to see how it compares to other materials.
Steel has several properties that make it suitable for a range of uses in both construction and manufacturing. The seven most important properties of steel include:
Hardness is used to determine a metal’s ability to withstand abrasion resistance or friction. Hardness is measured in kilogram-force (kgF), which is the force exerted by a mass of 1kg in a gravitational field of 1 standard gravity (9.80665 newtons).
The specific hardness of steel will depend on the grade being tested and the type of test used, but steel is around 2.5 times denser than aluminium, which translates to much higher hardness levels across all grades.
Toughness is the ability of a material to resist brittle fracture. The tougher the material, the more energy can be absorbed before fracture. The toughness of steel can vary depending on the grade of steel being tested and environmental conditions.
Toughness is measured using the Charpy V-notch impact test. This measures the energy required to fracture a steel specimen at a specified temperature. The more the steel deforms before breaking, the tougher it is.
Yield strength measures the amount of stress a metal can withstand without permanent deformation. Yield strength is measured using a tensile test where the metal is pulled at a gradually increasing rate until fracture.
Structural steel has an incredibly high yield strength of 250-1000 N/sq mm. This is much higher than comparable grades of aluminium, which have yield strengths of between 30-500 N/sq mm.
Tensile strength measures the pulling stress a material can be subjected to until fracture. Tensile strength is calculated by dividing the load-carrying capacity by the material weight.
The tensile strength of structural steel is 400 megapascals (MPa). This is much higher than aluminium, which has a tensile strength of just 90 MPa, but aluminium is a much lighter material and it has better heat dissipation properties.
Malleability is the ease with which a metal can be shaped by pressing, rolling or hammering. Malleability is measured by carrying out a compression test to determine how much pressure the metal can withstand before fracture.
Steel is extremely malleable when annealed, which allows it to be shaped relatively easily without losing strength. But grade-for-grade, steel is less malleable than other alloys such as aluminium.
Ductility refers to the ability of a metal to withstand deformation without fracture. In other words, how far the steel can be stretched before tearing. Metals with high ductility can withstand high pressures before fracture which is a benefit in a range of engineering applications.
The ductility of steel varies depending on its compound and grade. Increasing the carbon content of steel for example will increase its strength but decrease its ductility. But generally speaking, grade-for-grade steel is slightly less ductile than aluminium.
The high iron content of steel gives it magnetic properties, but not all steel is magnetic. Most stainless steels, except for Austenitic stainless steel, are non-magnetic despite containing high levels of iron.
This has a huge impact on the performance of the material depending on its application. For example, a magnet can be used to quickly sort steel from other non-magnetised metals during the manufacturing process.
As you can see, steel has a range of properties that make it useful for use in manufacturing and construction projects. But there is another advantage to steel we have not touched on.
The abundant materials needed to make steel, combined with efficient manufacturing processes, make steel one of the most cost-effective building materials. So no wonder steel is the metal of choice for building contractors and manufacturers around the world!