303Se Stainless Steel: Selenium-Enhanced Free-Machining Alloy

 

What's unique about 303Se's composition?​

It contains 17-19% chromium, 8-10% nickel, and 0.15-0.3% selenium (instead of sulfur) to enhance machinability. The selenium forms inclusions that break chips, reducing tool wear without the same corrosion trade-offs as sulfur.​

 

How does 303Se perform in terms of machinability?​

It offers excellent machinability, comparable to 303, with smooth chip formation and reduced tool wear. Selenium's advantage is that it doesn't harm corrosion resistance as much as sulfur, making it a better choice for mild corrosive environments.​

 

What are its corrosion resistance properties?​

303Se has better corrosion resistance than 303, closer to 304, thanks to selenium's lower impact on the oxide layer. It resists rust in dry air and fresh water, performing adequately in mild chemical settings.​

 

How does 303Se compare to 303 in mechanical properties?​

Both have similar tensile strength (around 515 MPa) and hardness, but 303Se has slightly better ductility, with elongation around 30%. This makes it more formable than 303 for simple bending or shaping tasks.​

 

What are 303Se's typical applications?​

Commonly used in precision-machined parts like valves, gears, and fasteners that need better corrosion resistance than 303 can provide. It's also found in food processing equipment components and marine hardware where mild corrosion resistance matters.