We all know steel is the world’s most important manmade engineering and construction material consisting iron and carbon i.e., steel is an alloy of iron with few percentages of carbon. There are many classifications of this material among which carbon steel and stainless steel are the most common. While the two steels may look similar, there are many subtle differences.
Whatnots about Stainless Steel
Did you know that stainless steel is also called inox steel, or simply inox? Yes, the word inox was derived from the French word inoxydable, which means inoxidisable. With a wide range of applications from screwdrivers to automotive engines and industrial machines, this alloy has now become increasingly common. Inox steel is comprised of iron along with chromium as well as carbon, although the ratios of these components may vary.
An important characteristic of stainless steel is its chromium composition. As already mentioned above stainless steel comprises of iron that oxidises when exposed to the environment. This causes the material to rust and degrade. However, even the presence of small amounts of chromium in stainless steel can provide protection against rust and corrosion. It has been proved that chromium attaches itself more readily with oxygen when compared to iron. And hence, it creates a chromium oxide layer over the steel and protects the rest of the material from corrosion.
Whatnots About Carbon Steel
Carbon steel is an alloy of iron with some carbon along with other limiting elements to reduce factors like corrosion and degradation. Basically, characterized as a high carbon content with up to 2.1% of carbon consistency, the American Iron and Steel Institute (AISI) further defines carbon steel by meeting the following criteria:
- There is no minimum content requirement for chromium, cobalt, nickel, titanium, tungsten, vanadium or other corrosion-resistant metals.
- The minimum required content of copper shall not exceed 0.40%.
- The maximum content of manganese shall not exceed 1.65%.
- The maximum content of copper shall not exceed 0.6%.
- The maximum content of silicon shall not exceed 0.6%.
And not just it, carbon steel is also categorized as mild, medium, high and ultra-high carbon steel depending on the exact amount present. Carbon components are well known to be covalently strong and extremely hard based on their carbon content. The mild or low carbon steels are some of the most commonly used kinds. While these are softer, weaker and easy to machine or weld, high carbons on the other hand are stronger and significantly harder to machine or process.
Properties of Carbon Steel vs Stainless Steel
With both the types of steels having various types and grades among themselves, it is quite tedious to point out the differences in the properties of each. Unlike stainless steel, the chromium content in carbon steel is usually not sufficient to form a chromium oxide layer and therefore allows oxygen to oxidize the iron in it. This ends up forming iron oxide, in other words, rust which leads to corrosion and degradation of the material. So, if the deciding factor is corrosion-resistance, then stainless steel is the best.
Inox steel also comprises of large amount of nickel which makes it more ductile than carbon steel. Some stainless steels also contain alloying elements that increase its strength. And hence, carbon steels with very less amounts of carbon might not match the tensile strengths of these stainless steels. However, if there is enough amount of carbon in the carbon steel, it is more readily heat treated than any stainless steel.
Low or mild carbon steel often tend to lose their shape or deform under stress or heat and not break. This property of ductility makes them easy to weld or machine. On the other hand, high-carbon steel is very hard in nature. This property provides resistance against abrasion and helps retain original shape. Heat treating high carbon steels makes them extremely good thermal conductors and strong materials while losing the property of ductility and malleability.
Appearance of Carbon Steel vs Stainless Steel
A normal person can easily make out the difference between the materials with their appearance. Stainless steel is lustrous while carbon steel is dull with a matte finish. While both materials can give the lustrous, bright, shiny look after being sanded or polished, a quick coating of paint or clear coat immediately after polishing is required to keep carbon steel from tarnishing or rusting. Also, a little scratch requires carbon steel to be re-painted to prevent from corroding whereas stainless steel will still stay lustrous in the areas scratched.
Cost Efficiency of Carbon Steel vs Stainless Steel
Both the steels are mixtures of varying ratios of different components. Stainless steel is a composition of various such alloying materials like chromium, nickel, manganese etc. Hence stainless-steel costs more than carbon steel, which consists of only iron and carbon elements that are relatively affordable.
Uses of Carbon Steel vs Stainless Steel
As carbon steel is all about carbon content, its usage will only depend on the amount of carbon present in the material. For example, low or mild carbon content steels can be used for wrought iron or fencing while medium carbon steels can be used for construction works like building bridges and high carbon steels can be used for coils and steel wires. Also, the strength and durability of this material makes it possible for carbon steels to also be used for manufacturing cutting tools that have heavy duty cutting edges such as knives and saws. Stainless steel being rust-resistant, any industrial which uses water during production can use it as their primary metal material.
The Final Verdict
Both carbon and stainless steel are different and nevertheless is one superior to the other. The final decision over which gains priority above the other totally depends on considering the advantages and disadvantages of both the materials that match the requirements at that moment. In the end, the choice will depend on the specifics of the job or project.
