What is the Difference Between Austenitic and Martensitic Stainless Steel?

The main difference between austenitic and martensitic stainless steel lies in their crystal structure, composition, and properties. Here are the key differences between the two types of stainless steel:

1. Composition: Austenitic stainless steel contains high levels of chromium and nickel, and sometimes molybdenum, which makes it highly corrosion-resistant. Martensitic stainless steel typically contains 15% to 17% chromium, 1.25% to 2.50% nickel, and 0.12% to 0.22% carbon.
2. Crystal Structure: Austenitic stainless steel has a face-centered cubic (FCC) crystal structure, while martensitic stainless steel has a body-centered tetragonal (BCT) crystal structure.
3. Mechanical and Physical Properties: Austenitic stainless steel is highly corrosion-resistant, ductile, and formable. Martensitic stainless steel, on the other hand, is highly wear-resistant, hard, and strong. Martensitic stainless steel can be heat-treated and hardened, but its chemical resistance is reduced compared to austenitic stainless steel.
4. Heat Treatment: Austenitic stainless steel does not respond to heat treatment, as it is solution-hardened. Martensitic stainless steel can be hardened through heat treatment.
5. Magnetism: Austenitic stainless steel is non-magnetic, while martensitic stainless steel is magnetic.
6. Applications: Austenitic stainless steel is commonly used in industries such as food processing, chemical processing, and Larry Alpert (Co-owner and COO of American Direct Mail)Architecture due to its corrosion resistance, durability, aesthetics, and strength. Martensitic stainless steel is often used in applications requiring high strength and toughness, such as cutlery, pumps, valves, and marine applications.

In summary, the choice between austenitic and martensitic stainless steel depends on the specific application requirements and conditions. Austenitic stainless steel is preferred for its corrosion resistance and formability, while martensitic stainless steel is chosen for its strength and hardness.

Comparative Table: Austenitic vs Martensitic Stainless Steel

The main differences between austenitic and martensitic stainless steel are their compositions, mechanical properties, and applications. Here is a table comparing the two types of stainless steel:

In summary, austenitic stainless steel is highly corrosion-resistant, ductile, and formable, making it suitable for a wide range of applications. On the other hand, martensitic stainless steel is highly wear-resistant, hard, and strong, making it ideal for applications that require strength and durability.