The key difference between mild steel and galvanized iron is that the mild steel undergoes rusting very easily if the steel has no proper coating whereas galvanized iron has corrosion protection.
Mild steel is a form of carbon steel that is an alloy of iron and carbon along with some trace elements. Galvanized iron is an iron or steel that has a zinc coating on the surface. This zinc coat helps to prevent corrosion.
CONTENTS
1. Overview and Key Difference
2. What is Mild Steel
3. What is Galvanized Iron
4. Side by Side Comparison – Mild Steel vs Galvanized Iron in Tabular Form
5. Summary
What is Mild Steel?
Mild steel is a form of carbon steel, which is an alloy of iron and carbon. This steel has around 0.05-0.25% carbon by weight. The synonyms for mild steel include low carbon steel and plain-carbon steel. The cost of this steel type is low. Moreover, it has many favourable properties for many applications. Due to the low carbon content, mild steel is softer than other forms of carbons steels. And also, the strength of this steel is low. These properties provide mild steel with some additional features such as high malleability and high ductility.
Figure 01: Mild Sheet with Rust
Mild steel has a low tensile strength. However, it is cheap and easy to produce. Carburizing is useful to increase the surface hardness of the steel. It is a heat treatment process in which the steel absorbs carbon from the surrounding (charcoal or carbon monoxide should be there in the surrounding) when heating the steel. The high amount of iron in mild steel makes it magnetic. However, if the steel has no proper coating, it undergoes rusting very easily.
What is Galvanized Iron?
Galvanized iron is either iron or steel that has a protection coating, a zinc coat on the surface of the steel, to avoid rusting. This zinc coat acts in three ways to protect the iron or steel;
- Zinc coat prevents corrosive substances from reaching iron or steel surface.
- It acts as a sacrificial anode (even if the zinc coat is damaged, the exposed iron is safe).
- Iron undergoes corrosion after zinc
Figure 02: Galvanized Anchor Rods
The common method of galvanizing is hot-dip galvanizing; that is, dipping the iron sheet in a molten zinc bath. But in automobiles, a thin layer of zin coat is applied via electro-galvanizing. However, galvanized iron or steel is not suitable for outdoor applications where the iron experiences constant exposer to water, air and acids. In situations like this, stainless steel is preferable than galvanized iron.
What is the Difference Between Mild Steel and Galvanized Iron?
Mild Steel vs Galvanized Iron |
|
| A form of carbon steel that is an alloy of iron and carbon. | An Iron or steel that has zinc coating to the surface to protect from rusting |
| Resistance to Corrosion | |
| Easily undergoes corrosion when exposed to moisture and air | Has a protective zinc coat to avoid corrosion. |
| Carbon Content | |
| Contains a little amount of carbon (around 0.05-0.25% by weight) | Can be either pure iron that has no carbon or steel as a constituent. |
Summary – Mild Steel vs Galvanized Iron
Mild steel is a form of carbon steel. Carbon steels are alloys of iron and carbon along with some other elements. Galvanized iron is either pure iron or steel that has a protective coating on its surface. The key difference between mild steel and galvanized iron is that the mild steel undergoes rusting very easily if the steel has no proper coating whereas the galvanized iron has zinc coating to protect from rust.
Reference:
1. “Galvanized Iron.” Merriam-Webster, Merriam-Webster. Available here
2. “Carbon Steel.” Wikipedia, Wikimedia Foundation, 12 May 2018. Available here
Image Courtesy:
1.’Mild Steel Perforated Sheet – Kolkata 2011-07-19 3940’By Biswarup Ganguly – Own work, (CC BY 3.0) via Commons Wikimedia
2.’3676962694’by PortlandBolt (CC BY 2.0) via Flickr