Unlike popular belief, steel isn’t an elemental metal like iron. Instead, steel is an iron-based alloy made primarily of iron and carbon, with minute traces of other elements. Depending on the amount of carbon present in the alloy and the proportions of other alloying elements, we can categorize steel as carbon steel and stainless steel.

What Is Carbon Steel?

All steel contains carbon, but not all steel is considered carbon steel in general terminology. Instead, carbon steel refers to an alloy that consists primarily of iron and varying amounts of carbon and very minute traces of other alloying elements.

The addition of carbon to iron serves to fill in the microscopic gaps within the crystalline structure of iron, which has horrible mechanical properties, giving the steel alloy its tensile strength and flexibility. In most cases, steel alloys contain anywhere between 0.002% and 2.14% carbon by weight. Anything higher than that is considered cast iron.

The exact amount of carbon depends on the specific type of carbon steel. For example, low-carbon steel has less than 0.3% carbon, and it’s best suited for industrial applications. Medium-carbon steel has between 0.3% and 0.6% carbon, with 1.6% manganese as an alloying element which significantly improves the strength of the steel.

High-carbon steel has anywhere between 0.6% and 1.7% carbon content by weight and up to 1.65% manganese. High carbon content still makes this incredibly tough and hard but also incredibly difficult to form, cut, or weld. That’s why it’s best suited for making milling and cutting tools, such as high-carbon steel knives.

Stainless Steel

Stainless steel is a metal alloy composed of the same properties as carbon steel; it has iron as the base element and carbon as the primary alloying element. However, compared to carbon steel, which is susceptible to corrosion, stainless steel has one key distinction: its exceptionally high corrosion resistance.

These corrosion-resistant properties are attributed to high chromium content within the alloy, which goes as high as 20% by weight, depending on the grade of stainless steel. The chromium within the alloy reacts with oxygen from the environment and creates a passive protective layer of chromium oxide across the material surface.

This layer further prevents the oxidation of iron content within the alloy and the formation of iron oxide. Chromium oxide forms very quickly, so stainless steel is considered a self-healing alloy.

Depending on the actual grade of stainless steel, additional alloying elements, such as molybdenum, nickel, copper, or titanium enhance the material’s properties, such as durability, ductility, yield strength, and corrosion resistance.

Just like carbon steel, stainless steel also comes in different types of stainless steel, mostly categorized by their chemical composition and crystalline structure:

• Austenitic stainless steel has a relatively high percentage of chromium, relatively low nickel content, and non-magnetic properties, which is why it’s mostly used for surgical equipment and implants.
• Ferritic stainless steel has a relatively low carbon content, no nickel, and relatively high chromium content. This alloy can easily cold form to a reasonable hardness.
• Martensitic stainless steel has a relatively high carbon content and up to 18% of chromium by weight, with minute traces of nickel. It has great ductility and strength, with very good corrosion resistance.

Thanks to its fantastic properties, stainless steel is one of the most widely spread steel types, and it’s used in mechanical engineering to produce various types of nut fasteners, hinges, handles, and latches.

Carbon vs. Stainless Steel

Source: Pixabay

Stainless steel and carbon steel differ, and sometimes to an extensive degree. Carbon steel is generally considered stronger and more durable compared to stainless steel, but stainless steel doesn’t corrode, and it’s much more aesthetically pleasing.

Different types of steel are extremely important for specific types of applications. Knowing the right type of steel means the difference between an effective, durable product compared to one that fails to meet spec definitions. Learn more about the steel products we offer at Reid Supply by visiting our site.