Steel is one of the most widely used and recycled metal materials on earth. Back in the day, the utilization and application of steel were limited due to few variations. However, today from stainless and high-temperature steels to flat carbon products, steel along with alloys feature different properties to accommodate a wide variety of applications. Additionally, the relatively low cost of production and high strength makes it usable for countless products.
What is Steel?
Contrary to popular belief, steel is not a metal but an alloy. It consists of the metallic element iron, which is not just used for construction but also the formation of red blood cells by our bodies.
Upon heating iron at very high temperatures, the lattice structure created by the adjoining atoms changes shape and allows other elements such as carbon to infiltrate the lattice and make its way through the cracks. While the lattice cools down, the other elements are baked inside the lattice, becoming a part of the lattice and ultimately changing the properties of the material.
When it comes to discussing steel properties, yield strength is the most important. The yield strength is the point at which steel begins to change shape or deform under a significant increase in the rate of strain due to stress. At this point, ductile materials such as low carbon steel will begin to deform.
The application of steel largely depends on the yield strength. The reason is that once a material goes past the yield point, its life is significantly reduced. As a result, such yielded materials are used for limited purposes and to ensure maximum strength and life, manufacturers have to use advanced mechanical techniques for the clients.
Elongation is yet another important property of steel interms of applications. It is a process that measures how long will the material stretch before it fractures. This number is determined by dividing the percentage of total elongation by the initial length.
For instance, a 1-inch rubber band that stretches or elongates to 2-inches before fracturing will have an elongation of 100% at fracture. This means that the brittle the material, the less it will elongate before fracturing.
Materials such as glass or concrete are amongst the most brittle materials and will fracture upon experiencing any type of elongation. Therefore, metals differ interms of the elongation percentage. Low-carbon steels and alloys tend to elongate comparatively more than high-carbon steels.
The hardness measures how much a material resists local plastic deformation due to mechanical abrasion or indentation. Hardness players a huge role in the manufacturing process. The reason is that materials with high hardness cannot be easily formed similarly to or machined like materials with lower hardness.
Typically, a heating treatment process is used to harden the metals once they are formed or machined to meet the specifications of the client without increasing the manufacturing costs. With that being said, metals also vary based on the level of hardness and types. Even though there are many but the most popular happens to be the Rockwell scale.
The Rockwell test under a large load measures the depth of penetration of an indenter and compares it to the preload penetration. While other hardness tests are considered destructive, the Rockwell test is not. There are three types of Rockwell hardness scales, HRA, HRB, and HRC. The selection of the scale depends on which best represents the material hardness.
Types of Steel & Their Properties
Carbon steel is offered in three types. Low-carbon, medium-carbon, and high-carbon steel. Each type differs based on the properties. Low-carbon steel as the term suggests features the lowest carbon content.
It has high weldability, low hardenability, low machinability, high workability, and low wear resistance. However, the production cost is low and its application extends to ships, car bodies and civil structures, etc.
Medium Carbon Steel on the other hand features relatively more carbon content and has medium to low weldability, high to medium hardenability, high to medium or low machinability, high to medium or low workability and medium wear resistance. It is used in the manufacturing of crankshafts, couplings, and cold-headed parts.
Finally, high-carbon steel contains the most carbon content. However, its weldability is very low. The hardenability of high-carbon steel is very high, while the machinability and workability are both quite low in addition to wear resistance being high. It is used in the manufacturing of springs, music wire, and cutting tools.
Common Uses of Steel
Buildings and Infrastructure
Steel is used to create reinforcing bars, internal walls, roofs, and ceilings in addition to other structural sections. Plus, stainless steel is also used to manufacture high-quality kitchen equipment and HVAC systems. However, the type of steel used and its application depends on the project.
Different infrastructure projects require various types of steel designed to meet the unique requirements. For instance, if the infrastructure project is being carried out at a location where rust and corrosion is high then stainless steel is going to be the most preferred option.
Besides bridges and other such projects, steel is also used in fueling stations, rail tracks, and ports, etc. This ensures that the projects have a lengthy lifespan being able to withstand extreme weather conditions.
Even though vehicle manufacturers are gradually shifting to the utilization of aluminum for producing vehicles but steel is still used to make the exterior as well as the body structure. Moreover, it is also used in the suspension and the drive train.
However, the type of steel used in vehicles significantly differs from traditional steel due to the weight reduction factor. Manufacturers utilize and implement the latest and most modern techniques to produce advanced high-strength steals that can bear impact and keep the weight down at the same time.
With the advancement of technology and manufacturing processes, the application of steel is only destined to increase. Although the manufacturers are continuously looking for alternatives but considering the variety of steel available today, it is one of the most preferable options for infrastructure and other related projects.