416 Stainless Steel: Free-Machining Martensitic Alloy

 

What's distinctive about 416's composition?​

It contains 12-14% chromium, 0.15% max carbon, and added sulfur (0.15-0.35%) to improve machinability. The sulfur forms sulfide inclusions that break chips, reducing tool wear during machining.​

 

How does 416 perform in terms of corrosion resistance?​

It offers moderate corrosion resistance in dry environments, similar to 410 but slightly lower due to sulfur. It can rust in moist or corrosive settings, making it unsuitable for marine or high-humidity applications.​

 

What are its mechanical properties after heat treatment?​

When heat-treated, 416 achieves a tensile strength of 650-1000 MPa and hardness of 25-36 HRC. It has good strength but lower toughness than non-free-machining martensitic steels, due to its sulfur content.​

 

How does 416 compare to 410 in machining?​

416 is far easier to machine than 410, with better chip formation and reduced tool wear. This makes it ideal for complex parts requiring precision machining, though it sacrifices some corrosion resistance and toughness for machinability.​

 

What are 416's typical applications?​

Commonly used in fasteners, valves, and automotive components where easy machining is prioritized. It's also found in pump shafts, gears, and electrical fittings that don't require high corrosion resistance.