While all types of steel technically contain some amount of carbon, there are drastic differences in terms of performance, appearance, and recommended uses for steels typically labeled carbon steels and stainless steels.
By adjusting the amount of carbon and other additives by even a fraction of a percent, you impact a range of traits — including malleability, ductility, heat conductivity, brittleness, and corrosion resistance.
Let’s go over some of the common terms used to differentiate between carbon and stainless steels and recommended uses for each.
Carbon Steel 101
Carbon steel typically contains between 0.12% and 2% carbon.
Depending on the exact amount present, carbon steels will be classified into 1 of 4 categories:
- Mild Steel: Between 0.16% and 0.29% carbon
- Medium Carbon Steel: Between 0.30% and 0.59% carbon
- High Carbon Steel: Between 0.6% and 0.99% carbon
- Ultra-High Carbon Steel: Between 1.0% and 2.0%
While specific characteristics will vary based upon other materials in the alloy, heat treatments, and other considerations, steel with higher carbon content tends to gain hardness and heat conductivity while losing malleability and ductility.
This makes high-carbon and ultra-high carbon steels ideal for uses such as knife making where maintaining a precision edge for as long as possible is key and worth the added brittleness.
Heat treatments can further enhance the attributes of high carbon and ultra-high carbon steels for further hardening and resilience.
However, for machining, mold making, or other precision fabrications, lower carbon steel provides better flexibility.
If you need to bend the steel or weld as part of fabrication, mild steel will also outperform stainless in a range of situations.
Carbon Steel vs Stainless Steel: Key Considerations
With the basics of carbon steel out of the way, we can discuss the major differences.
The most noticeable difference is the appearance and corrosion resistance.
Since carbon steel lacks the chromium of stainless steel it does not have the same luster or corrosion resistance. Most carbon steel has a matte finish that is prone to discolouration and staining.
If appearance, easy cleaning, or corrosion resistance are key, stainless is likely the better option.
But there’s also a cost consideration…
If parts are not visible and do not require high corrosion resistance, carbon steel will often provide a cheaper alternative to comparable stainless steel grades.
This makes carbon steel one of the most popular types of steel for architectural and structural uses.
Ultimately, much like choosing any grade of steel, deciding whether carbon steel or stainless steel is the best fit for your next product or project is a complex decision.
Choosing a steel with required traits will impact both the final result and the overall cost of your steel investment.
As a leading source of steel products throughout Canada for more than 40 years, Unified Alloys has the expertise and selection to help you find the perfect solution for your needs. With a quick phone consultation, we can help you decide the best steel grades and products for your next project.