What is Carbon Steel

Before delving into the characteristics of carbon steel, let’s first clarify the definition of steel. 

Steel is a type of alloy based on iron. Pure iron is brittle and prone to rust, making it unsuitable for industrial applications. To address this, carbon is added to iron along with elements like manganese and phosphorus, to create an alloyed material. The term steel specifically refers to those compositions with a carbon content ranging from approximately 0.02% to 2.14%. In contrast, iron has classified to have below 0.008%. of carbon content.  

As the carbon content in iron increases, it becomes harder, but at the same time, it becomes more brittle. While it gets less prone to deformation under force, it also becomes more susceptible to breaking, especially when subjected to sudden impact or forces beyond its tolerance. This is why materials used for machinery and structures need to possess both hardness and strength. 

Steel contains just the right amount of carbon to balance hardness and strength in iron. 

As mentioned, various other elements like manganese, chromium, and titanium are added to steel to create alloy steel and special steel, each with distinct characteristics. Special steels with features like rust resistance or high-temperature resistance are developed based on specific purposes. 

Among the different types of steel, carbon steel refers to the steel that does not fall under alloy steel or special steel. In other words, carbon steel is steel in its natural state, without the addition of specialized elements or processes. Carbon steel is defined by having an elemental content of elements other than iron and carbon that is below specified values. For instance, chromium is limited to 0.3% or less, and titanium to 0.05% or less. 

Carbon steel is classified based on its carbon content, resulting in three categories: low carbon steel, medium carbon steel, and high carbon steel. 

Low carbon steel refers to materials with a carbon content ranging from 0.02% to 0.25%, medium carbon steel has a carbon content between 0.25% and 0.6%, and high carbon steel contains 0.6% to 2.14% carbon.   

The most widely used type of steel: What is SS400?

SS400 belongs to a category of SS materials (Structural Steel) known as general structural rolled steel. 

SS400 is a structural steel with high tensile strength, equal to 400N/mm² or more. 

SS400 is known for being more affordable and accessible compared to other metal materials. It is also easy to process through methods like welding and cutting. Additionally, it is available in sheet form and is commonly used for sheet metal processing, laser cutting, and similar applications. However, SS400 cannot undergo heat treatment (annealing). It is also prone to rusting, so it requires anti-corrosion treatments like plating or blackening. 

Applications of SS400

SS400 is used as a structural material for bridges, ships, and more, spanning a wide range of applications from machinery to construction. When thinking about creating something using iron or steel, it’s not an exaggeration to say that SS400 is the material that designers first consider. SS400 is a material that is widely and commonly used.