Stainless steel grades are divided into five primary subfamilies, each of which is characterized by one of three crystalline structures: austenitic; ferritic; or martensitic. Nickel (Ni) is a key alloying component for each of these phases, but the promotion of distinct crystal structures relies on tight volumetric control of a stainless steel’s chemical composition. Ferritic and martensitic stainless steels, for example, are both characterized as body-centered cubic (BCC) crystal structures with significant deviations from one another with regards to their alloying composition. Ferritic alloys typically display mere trace levels of nickel and as much as 27% chromium (Cr), while martensitic stainless steels rely on increased volumes of both nickel and carbon (C).
This blog post will explore martensitic stainless steel in more detail.
Outlining Martensitic Stainless Steel
As mentioned, martensitic stainless steels comprise a BCC crystal structure that can be altered through heat treatment. This depends on the microstructural arrangement of the various alloying elements; primarily iron (Fe), chromium, carbon, and nickel.
The main alloying element of martensitic alloys, as with all stainless steel grades, is chromium. When introduced to iron alloys at sufficient concentrations, it imparts various strengthening and anti-corrosive effects, helping to render finished products in-oxidizable and highly resistant to aggressive media. The minimum chromium concentration for stainless steels is approximately 10.5%, but martensitic grades can afford to reduce this to as little as 5% through the introduction of additional elements such as vanadium (V).
The mechanical properties of martensitic stainless steel grades vary considerably due to the broad range of elemental dissimilarity within the subfamily. They typically display poor weldability due to the inherent brittleness of the material. However, they can be quenched and tempered to improve their toughness and expand their potential range of application.
The Importance of Martensitic Stainless Steel
Martensitic alloys were first discovered in the late 19th Century and were not adopted at commercial scale for several decades. First used to develop corrosion-resistant gun barrels, the material group has since expanded to include a range of carbon hardenable grades and novel nitrided low carbon alloys.
Applications of Martensitic Stainless Steel
Typical martensitic grades display reduced corrosion resistant properties compared to alternative stainless steel grades, but it is still suitable for fabricating microbial-resistant parts and components such as medical scalpels and internal clamps. It excels in engineering applications with its high hardness, toughness, and good resistant to various corrosives. As such, it is most commonly used to engineer mechanical valves and pumps.
Stainless Steels from Masteel
Masteel is one of the world’s leading suppliers of steel grades for almost any application. We can provide all five of the overarching stainless steel families for industrial or commercial sectors, with multiple grades within each subset.
If you would like to learn more about the various stainless steel grades, read our previous blog post: Outlining Austenitic Stainless Steel. Or, contact us for more information about our various products.