Difference Between Mild Steel and Stainless Steel

Main Difference – Mild Steel vs Stainless Steel

In general, steel is a metal alloy, composed of iron, carbon and some other elements. Steel production is one of the largest industries in the world. Steel can be categorized into several types depending on the amount of iron present and the percentages of other elements added. Mild steel and stainless steel are two such types of steel. The main difference between mild steel and stainless steel is that mild steel is composed of iron and carbon as the major constituents whereas stainless steel is composed of iron and chromium as major components.

Key Areas Covered

1. What is Mild Steel
      – Composition, Properties, Uses
2. What is Stainless Steel
      – Composition, Properties, Uses
3. What is the difference between Mild Steel and Stainless Steel
      – Comparison of Key Differences

Key Terms: Carbon, Chromium, Ductility, Ferromagnetic, Iron, Mild Steel, Plain Carbon Steel, Stainless Steel, Steel

What is Mild Steel

Mild steel is a type of steel which is composed of iron and carbon as major components. The main difference between normal steel and mild steel is that mild steel contains a very low carbon percentage than normal steel. Due to this reason, mild steel is also called plain carbon steel. The carbon content may vary from 0.05% to 0.25%. The properties of mild steel are mainly dependent on this little amount of carbon.

The low carbon content causes the ductility of mild steel to be increased. Ductility is the ability of a solid material to get deformed when a pressure is applied. The other elements present in mild steel includes manganese, silicon, etc. Due to the ductility of mild steel, it is machinable and weldable. As there is a high amount of iron present, mild steel is ferromagnetic. In other words, mild steel is easily attracted to a magnetic field. But the adverse effect of the presence of iron is iron oxidation. This iron oxidation causes the formation of rust and makes the steel corrode in a moist environment. Therefore, mild steel should be coated with a paint.

The properties ductility and weldability cause mild steel to be used in the production of pipes and pipe fittings. Mild steel is not brittle and is used as building material. Famous skyscrapers and bridges are made of mild steel due to their durability.

Figure 1: Mild Steel used as a Building Material

What is Stainless Steel

Stainless steel is a type of steel which is composed of iron and chromium. It is considered as a metal alloy. It has about 10% of chromium mixed with iron. The other metal elements present in stainless steel are nickel, molybdenum, titanium, and copper. Non-metal additions mainly include carbon.  

The purpose of mixing chromium is to prevent iron from oxidizing. This avoids rusting of the steel and gives a corrosion resistance property to steel. Chromium makes an oxidized layer on the surface of the steel which is called “passive layer”. This prevents iron from oxidation. However, it is not fully resistant to corrosion, especially in conditions like high concentrated salt water.

Stainless steel can withstand high temperatures. Therefore, stainless steel is used to make kitchen items. Unlike normal steel, stainless steel has a shiny appearance which is very attractive.

Figure 2: Stainless Steel Kitchen Items

Difference Between Mild Steel and Stainless Steel

Definition

Mild Steel: Mild steel is a type of steel which has a less amount of carbon along with iron.

Stainless Steel: Stainless steel is a type of steel that is made of chromium with iron.

Components

Mild Steel: Mild steel is composed of iron and carbon as major constituents. Other elements include manganese and silicon.

Stainless Steel: Stainless steel is composed of iron and chromium. Other elements are nickel, molybdenum, titanium, and copper.

Corrosion Resistance

Mild Steel: Mild steel is not resistant to corrosion.

Stainless Steel: Stainless steel is resistant to corrosion.

Amount of Iron

Mild Steel: Mild steel may contain about 98% of iron.

Stainless Steel: Stainless steel is composed of about 90% of iron.

Weldability

Mild Steel: The weldability of mild steel is high.

Stainless Steel: Weldability of stainless steel is low.

Ductility

Mild Steel: Mild steel is ductile.

Stainless Steel: Stainless steel is not ductile.

Conclusion

Steel is very important in the construction field and many other industries. Mild steel and stainless steel are two types of steel categorized according to their composition. The main difference between mild steel and stainless steel is that mild steel is composed of iron and carbon as the major constituents whereas stainless steel is composed of iron and chromium as major components.

References:

1.”Stainless steel.” Encyclopædia Britannica. Encyclopædia Britannica, inc., n.d. Web. Available here. 16 June 2017. 
2.Anu Dang. “Mild steel.” LinkedIn SlideShare. N.p., 07 Mar. 2014. Web. Available here. 16 June 2017.

Image Courtesy:

1. “414035” (Public Domain) via Pixabay
2. “Cuisinart-mcp-12n-review” By Sintoa – Own work (CC BY-SA 4.0) via Commons Wikimedia