What is 303Se per AMS 5641?

AMS 5641 is a specification for a variant of 303 stainless steel. Nominal Chromium content is 18% and nominal Nickel content is 9%. Selenium is added to improve machining
characteristics. UNS designation is UNS S30323. The most common applications are for components that require forming or swaging in addition
to improved machining characteristics in fabrication. Product supplied to this specification is in the form of Bars,Wire, and Forgings in the solution
treated (aka solution annealed) condition. Don't forget to...Check the Specs!!