UNS S41600, commonly known as 416 stainless steel, is a free-machining martensitic stainless steel known for its enhanced machinability due to the addition of sulfur. This modification allows for higher cutting speeds, longer tool life, and improved surface finishes compared to other stainless steels. Typical applications requiring close tolerances and high production rates, such as screws, nuts, bolts, and shafts, often utilize this material.
The material offers a good combination of strength, corrosion resistance, and hardness. While its corrosion resistance is lower than that of non-free-machining stainless steels like 304, it remains suitable for mildly corrosive environments. The heat treatability of this steel allows it to achieve high hardness levels, further enhancing its suitability for wear-resistant applications. Its development addressed the need for a stainless steel that could be easily machined while retaining adequate mechanical and chemical properties.