Difference Between Steel and Stainless Steel

Main Difference – Steel vs Stainless Steel

Steel and stainless steel are metal alloys. A metal alloy is a mixture of metals or a mixture of metals and other elements. Steel and stainless steel are metal alloys of iron; different elements have been added to iron in order to obtain varied properties. The main difference between steel and stainless steel is their resistance to corrosion; steel undergoes corrosion whereas stainless steel does not undergo corrosion.

Key Areas Covered

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

Key Terms: Carbon, Chromium, Corrosion, Iron, Nickel, Steel, Stainless Steel

What is Steel

Steel is a metal alloy composed of a mixture of iron and carbon. The percentage of carbon that is mixed will decide the properties of the steel. But the amount of carbon that is added will always be less than 1.5%. Apart from that, the properties of steel depend on other elements added and the impurities present in the alloy. The most commonly found elements in steel are manganese, tungsten, vanadium, phosphorous and sulfur. Various grading systems are also used to categorize steel into different groups according to their properties.

Types of Steel

• Carbon steels
• Alloy steels
• Stainless steel
• Tool steels

Carbon steel can be again divided into three groups as low carbon steel (mild steel), high carbon steel and medium carbon steel according to the percentage of carbon added to the iron. Alloy steel contains alloying elements such as silicon and aluminium.

Properties of Steel

• Strength
• Toughness
• Ductility
• Weldability
• Durability

The above properties make steel a desired substance to be used as a building material. However, rusting poses a major problem since steel is not resistant to corrosion. Therefore, steel is often painted with paints in order to avoid corrosion. Corrosion occurs mainly due to oxidation of iron atoms.  

Figure 1: Steel with rust on the surface

What is Stainless Steel

Stainless steel is a type of steel. Hence, it also is a metal alloy. It is a mixture of iron and chromium. Unlike the carbon content in normal steel, the chromium content of stainless steel is about 30%. Other elements such as copper, molybdenum, and titanium may be also present in stainless steel.

The most desired property of stainless steel is its corrosion resistance. Unlike normal steel, it does not undergo corrosion; therefore rusting is absent. This property makes it useful in the production of kitchen and healthcare products because it is safe to be used in moist environments. It also has a high heat resistance, making it suitable for the production of kitchen items. Stainless steel has a more attractive appearance than normal steel. According to their properties, stainless steel is also divided into sub-groups as follows.

• Duplex stainless steel
• Martensitic stainless steel
• Ferritic stainless steel
• Austenitic stainless steel

Figure 2: A spoon made of Stainless Steel

Difference Between Steel and Stainless Steel

Definition

Steel: Steel is a hard alloy composed of iron, carbon and other elements.

Stainless Steel: Stainless steel is an alloy of iron, chromium and other elements.

Composition

Steel: Steel is composed of iron and carbon (less than 1.5%) along with some other elements.

Stainless Steel: Stainless steel is composed of iron and chromium (about 30%) along with some other elements.

Corrosion Resistance

Steel: Steel is not resistant to corrosion.

Stainless Steel: Stainless steel is highly resistant to corrosion.

Rusting

Steel: Steel undergoes rusting in moist environments.

Stainless Steel: Stainless steel does not undergo rusting in moist environments.

Hardness

Steel: Steel is relatively very hard.

Stainless Steel: Stainless steel is also hard but easy to fabricate.

Heat Resistance

Steel: Steel is not very resistant to heat.

Stainless Steel: Stainless steel has a higher heat resistance.  

Uses

Steel: Steel is best to use as building material.

Stainless Steel: Stainless steel is used to produce kitchen items.

Conclusion

Stainless steel is also a type of steel but it is modified. That is to obtain desired properties out of the alloy. Both steel and stainless steel are used in different applications. Though stainless steel is a type of steel, it is distinguishable from steel due to the specific properties it has. The main difference between steel and stainless steel is that steel undergoes corrosion whereas stainless steel does not undergo corrosion.

References:

1.”Stainless Steel – High Temperature Resistance.” AZoM.com. N.p., 11 June 2013. Web. Available here. 14 June 2017..
2.”St St introduction.” Stainless Steel – General Information – St St Introduction. N.p., n.d. Web. Available here. 14 June 2017. 

Image Courtesy:

1. “856074” (Public Domain) via Pixabay
2. “Stainless Steel Spoon” (CC0) via Pexels