One of the greatest and most influential inventions of the modern age is the advances made in steel production. Where iron was common in most parts of the world for millennia, the discovery of different types of steel, made by alloying iron with other metals and changing its carbon content was one of the factors that allowed for the development of the modern world.
There are many different types of steel available today. Low-carbon (mild) steel is prevalent and easy to acquire, as is stainless steel. Both are used for different applications and are chosen based on their physical characteristics. What are the differences between stainless steel and mild steel?
The Importance of Alloying Elements
Ryan from The Green Gate Group said “The main difference between mild steel and stainless steel is the alloying elements that are used in the production process.”The majority ofall steel is comprised of iron, 90% or more by weight. The differences lie in the materials that they are mixed with (alloyed) while they are being produced.
Plain Carbon Steel
Mild steel, also known as plain carbon steel, is iron alloyed with carbon. Ranging from .05% to .25% carbon, mild steel makes a fantastic material for almost innumerable applications. It is easily molded, weldable, ductile (meaning it can be stretched and molded without losing its strength), magnetic, cost-effective, and much more. Steel products are easy to fabricate out of mild steel.
Stainless Alloy Steel
Stainless steel is iron alloyed with a minimum of 11.5% chromium. It is also alloyed with nickel and molybdenum to produce what is commonly known as “stainless” steel. This varies from mild steel in a number of significant ways.
- Stainless steel is corrosion resistant whereas mild steel is not.
- Mild steel is weaker than stainless steel, which has a higher tensile strength. This makes stainless steel better for application where there is to be extended duration of excessive force and wear.
- Stainless steel is not magnetic which is necessary for certain industrial, commercial, and aerospace applications.
Is the Magnetic Field of Steel Affected by the Alloying Process?
Yes. The ferromagnetism of steel is determined by its iron content. Mild steel has an iron content of 98% or more and stainless steel has only 90% or less. This makes stainless steel non-magnetic and mild steel very magnetic in comparison. Why would this matter?
Certain applications call for a certain level of magnetism while others, mainly aerospace and specific industrial processes, need a highly durable, corrosion resistant and non-magnetic material. Stainless steel can provide all these features for these industries.
How Does Corrosion Resistance Happen?
Metal corrosion (rust) happens when oxygen reacts with the iron in steel, creating iron oxide. This reaction will over time eat away at the steel, making it weaker. When iron is alloyed with chromium, chromium oxide is produced when it is exposed to oxygen. This reaction creates a protective layer of chromium over the iron, making it extremely resistant to any type of corrosion and while it is not “corrosion-proof”, it will last far longer than mild steel.