AM350, also known as AISI 420 Mod., is a type of martensitic stainless steel, with UNS J91540 and AISI 420 Mod. designation. It is an advanced material intended for components and assemblies that require good hardness, corrosion resistance and wear resistance. AM350 exhibits higher corrosion resistance than Type 420 and can be used in place of Type 420 in most applications.
AM350 is similar to Type 420, with the difference being a higher carbon content (0.30 % vs. 0.15 %) and an addition of Molybdenum. This modified alloy enhances both corrosion and wear resistance compared to Type 420. In a critical environment, AM350 can provide up to 4 times better corrosion resistance and double the wear resistance than Type 420.
AM350 is a martensitic type stainless steel which is a sub-category of the 400 series stainless steels. The 400 series gets its name from the 400 Mpa minimum yield strength. The 400 Mpa minimum sets the bar for all of the strength values, such as tensile strength, compressive strength and hardness, which are all higher because of the carbon content. When compared to the 300 series stainless steels, the 400 series stainless steels have a higher carbon content (0.6-0.9%) which gives them their hardness.
AM350’s composition is as follows: Carbon (C) 0.30%, Silicon (Si) 0.50%, Manganese (Mn) 1.00%, Chromium (Cr) 17.00%, Nickel (Ni) 5.00%, Molybdenum (Mo) 3.00%, Sulfur (S) 0.030%, Phosphorus (P) 0.040%.
The addition of molybdenum is what sets AM350 apart from the other 400 series stainless steels. Molybdenum increases the steel’s strength and contributes a broader range of corrosion resistance. Molybdenum is a metal capable of added hardness, strength, and resistance to wear and tear, which improves the metal’s overall performance in highly corrosive environments. Molybdenum also helps to prevent pitting.
AM350’s low carbon content and molybdenum provide good weldability and fabricability, though not as good as Type 304. To ensure good correlation between the weldment and the parent material, postweld heat treatment is beneficial. AM350’s good surface integrity and corrosion resistance allow for use in a variety of decorative and engineering applications.
AM350 is a good choice for use in applications such as tool and die components, fasteners, medical instruments and components, utensils, automotive trim pieces, springs, and light duty load bearing applications. Its high strength makes it useful in cutlery, kitchen appliances, and cutlery, and it also has uses in the chemical industry, marine industry and in oil and gas industries when used as drill collars and driveline components.
As well as good corrosion resistance AM350 has good wear resistance and can be heat treated to increase strength and wear resistance. It also has good thermal conductivity, and is more ductile than Type 420. The combination of these characteristics make it an excellent choice for many industrial and manufacturing applications.
