Written by BAALLA Fatima-ezzahra
Let’s take a closer look at everything surrounding us, from the smaller to the bigger objects. Moving from toothpaste; electronic gadgets such as televisions, phones, tablets; even kitchen utensils to the giant machines and rockets used by NASA. Which clearly showcases the importance of materials in our daily life.
The reason behind studying materials not only to understand the functioning but to use that knowledge in a way to make our life more comfortable. In fact, materials have undergone significant changes throughout time to meet the industry demands and requirements intending to suit particular purposes. For example, Iron (Fe), the metal of Group 8 (VIIIb) of the periodic table.
It is also known as the fourth most abundant element in the earth’s crust. It is one of the most predominantly used in metallic systems. The pure iron is soft, easy to shape, and reacts readily with oxygen. Due to the softness of iron, it doesn't enable us to support buildings, bridges. We need a strong iron and hard enough to withstand the loads and forces. That’s why there is a tendency to join iron with different elements in the form of alloys to make it more resilient. It is applicable not only for iron but for a range of different types of materials to change the physical properties aiming to fit the challenges of the manufacturing parts.
In this article, we will shed light on metal alloys and the crucial role that plays carbon steels for daily purposes.
Let’s take a brief walk back down the timeline and get to know those types of materials, their distinctive properties, and how they can be so useful and effective.
Non-ferrous metals have been used since early times before the discovery of ferrous metals, more precisely at the end of the Stone age and the beginning of the Copper Age. And after the bronze was discovered, the Bronze Age.
How can we differentiate between ferrous and non-ferrous materials?
Metal alloys are divided into two different categories: ferrous and non-ferrous metals.
Ferrous materials contain a percentage of iron while non-ferrous do not.
The ferrous system can be divided into steels and cast irons. Steel is a combination of iron with less than 2.1 percentage of carbon. And between 2.1 and 6.67 for cast irons but broadly speaking it should not exceed 4.1 percent for many practical engineering applications.
Carbon Steel: types, properties, & applications
Steels can be segregated to the low and high alloy, the amount of alloying refers to the added elements (Manganese, nickel, chromium…). Low alloy split into three different categories: Low carbon, medium carbon, and high carbon.
Low carbon steel: the percentage of carbon is less than 0.25. It’s not responsive to heat treatment (strengthening can only be reached by coldworking ) it has high ductility and malleability, making this type of carbon steel formable and machinable. On the other hand, we lose strength. Though, it is a good fit for applications needed less amount of strength and higher ductility and toughness such as automobile bodies, fasteners, shafts, and a variety of component parts.
Medium carbon steel: it has a carbon content between 0.25 to 0.6 percent. It can be heat treated due to the high percentage of carbon, therefore, the main mechanism of strengthening is no longer cold working, austenitizing is involved followed by quenching and tempering, giving the medium carbon steel a martensitic microstructure. Medium carbon steel has less ductility and toughness. There is a propensity to add elements, such as chromium, molybdenum, and nickel in order to enhance the heat treating capacity. Hardened medium carbon is harder and stronger but comes at the expense of ductility. As a result of its strength, it can be used for many applications: train wheels, crankshafts, gears.
High carbon steel: It has a carbon content between 0.6 and 1.4 percent. Because of the very high percentage of carbon, medium carbon steel is the hardest, strongest kind of carbon steel. It is used in hardened and tempered conditions which explain the increase in wear-resistance, hugely versatile, high-carbon steels are used in different applications that meet those requirements such as: cutting tools and hammers.
As the video shows the difference between mild steel and high carbon steel while applying the same type of heat treatment, those materials react utterly in a different way. This is why it is so important to know the suitable material appropriate for its application.