Differences between Stainless Steel vs Carbon Steel?

Carbon steel and stainless steel are two common materials used in various applications. Here are some of the main differences between them:

1. Composition: Carbon steel is an alloy of iron and carbon, with a maximum carbon content of 2.1%. Stainless steel is an alloy of iron, carbon, and at least 10.5% chromium, with other elements such as nickel and molybdenum added for specific properties.
2. Corrosion resistance: Carbon steel is susceptible to corrosion and rust, especially in moist or humid environments. Stainless steel has a higher resistance to corrosion due to the presence of chromium, which forms a protective oxide layer on the surface of the material.
3. Strength: Carbon steel has a higher tensile strength and yield strength than stainless steel. However, stainless steel is often used in applications where corrosion resistance is critical, such as in the food and medical industries.

Physical Properties

Physical parameter	Carbon Steel	Stainless Steel
Average Density	The average Density of Carbon Steel is 7850 Kg/m3	The average Density of Stainless Steel is 8000 Kg/m3. So Stainless Steel is slightly heavier than Carbon Steel
Co-efficient of Linear Thermal Expansion	The thermal expansion coefficient for Carbon Steel is usually less than that of stainless steel and varies in the range of (10.8 – 12.5) X 10-6 m/(m °C)	The expansion coefficient of Stainless Steel is comparatively more than that of Carbon Steel. Depending on grade, the coefficient varies in the range of (10-17.3) X10-6 m/(m °C). So, the thermal growth of Stainless Steel is more than Carbon Steel material.
Melting Point	The melting point of Carbon Steel is more than Stainless Steel. Typically Low Carbon Steel has a melting point of 1410 Deg C. The melting point of high Carbon steel ranges between 1425-1540 Deg C.	The melting point of stainless steel varies between 1375 to 1530 Deg C.

Mechanical Properties

Mechanical properties	Carbon Steel	Stainless Steel
Yield Strength	Low Carbon Steel: 180 to 260 MPa; High carbon Steel: 325 to 440 Mpa.	Ferritic Steel: 280 Mpa; Austenitic Steel: 230 MPA; Martensitic Steel: 480 MPA
Tensile Strength	Low Carbon Steel: 325 to 485 MPa; High carbon Steel: 460 to 924 Mpa.	Ferritic Steel: 450 Mpa; Austenitic Steel: 540 MPA; Martensitic Steel: 660 MPA
Elastic Modulus	2100000 Mpa	1900000 MPa
Shear Modulus	81000 Mpa	740000 MPa
Poisson’s Ratio	0.3	0.27

Other differences

Stainless Steel	Carbon Steel
Thermal conductivity is comparatively lower	Higher thermal conductivity.
Excellent wear resistance	Poor wear resistance.
Heat treatment of Stainless steel is difficult	Carbon Steel can easily undergo heat treatment.
Stainless Steel is easily cleanable	The cleanability of carbon steel is less than stainless steel.

4. Cost: Carbon steel is generally less expensive than stainless steel, although the cost can vary depending on the specific grades and applications.
5. Appearance: Stainless steel has a shiny, polished appearance and is often used in decorative applications. Carbon steel has a more matte finish and is often used in industrial applications.
6. Which is better carbon steel or stainless steel? It depends on the application and cost. For applications in a corrosive environment, stainless steel performs better than carbon steel due to its higher resistance to corrosion. For high-temperature and very low-temperature applications, stainless steel is preferred due to its better performance at extreme temperatures. However, for normal applications, carbon steel is often considered better as it is less expensive and has higher tensile strength than stainless steel. Ultimately, the choice between carbon steel and stainless steel depends on the specific needs of the application, including factors such as temperature, corrosion resistance, and cost.

Overall, the choice between carbon steel and stainless steel depends on the specific requirements of the application, such as the level of corrosion resistance, strength, and cost.