Carbon Steel vs Stainless Steel: Understanding the Contrast

Steel, as a fundamental engineering material, boasts a wide array of applications. Comprising primarily iron and carbon, steel is commonly categorized into two main types: Carbon Steel and Stainless Steel. In this discourse, we delve into the key disparities between these two broad categories, namely Carbon Steel versus Stainless Steel.

Density of Stainless Steel vs Carbon Steel:

The typical density of Stainless Steel, exemplified by 304 steel, stands at 8.0 g/cm3.

Conversely, typical steel registers a density of 8.05 g/cm3.

Density, representing the mass per unit volume, is an intensive property expressed as mass divided by volume (ρ = m/V). It is quantified in kilograms per cubic meter (kg/m3) in the SI system and pounds mass per cubic foot (lbm/ft3) in the English system.

Strength of Stainless Steel vs Carbon Steel:

Carbon Steel:

Low carbon steel exhibits a tensile strength ranging from 60,000 to 80,000 pounds per square inch (psi).

Medium carbon steel boasts a tensile strength of 100,000 to 120,000 psi.

Alloy steel showcases a tensile strength surpassing 150,000 psi.

Stainless Steel:

Austenitic stainless steel displays a tensile strength spanning from 72,000 to 115,000 psi.

Martensitic stainless steel ranges from 72,000 to 160,000 psi.

Ferritic stainless steel showcases a tensile strength between 65,000 to 87,000 psi.

Hardness of Stainless Steel vs Carbon Steel:

The Brinell hardness of stainless steel type 304 is approximately 201 MPa, while ferritic stainless steel (Grade 430) is about 180 MPa.

Martensitic stainless steel (Grade 440C) measures around 270 MPa, and duplex stainless steels (SAF 2205) exhibit a hardness of about 217 MPa.

Low-carbon steel boasts a Brinell hardness of roughly 120 MPa, whereas high-carbon steel stands at about 200 MPa.

Melting Point of Stainless Steel vs Carbon Steel:

Stainless steel type 304, ferritic stainless steel (Grade 430), and martensitic stainless steel (Grade 440C) all share a melting point around 1450°C, while low-carbon steel also converges at this temperature.

Machinability and Weldability of Carbon Steel vs Stainless Steel:

Carbon steel lends itself to easy machining and possesses commendable welding capabilities. Conversely, stainless steel necessitates specialized techniques for welding and machining. Moreover, stainless steel is notably harder than carbon steel, posing challenges for machining tools.

Other Differences:

Stainless Steel:

Lower Thermal Conductivity

Excellent Wear Resistance

Difficult Heat Treatment

Enhanced Cleanability

Carbon Steel:

Higher Thermal Conductivity

Poor Wear Resistance

Easy Heat Treatment

Lower Cleanability

The distinction between carbon steel and stainless steel often perplexes those unfamiliar with their properties. However, armed with this knowledge, we trust that this article has elucidated the significant variances between the two, aiding in clearer understanding.