303 is an “18-8” chromium-nickel stainless steel modified by the addition of selenium or sulphur, as well as phosphorus, to improve machinability and non-seizing properties. It is the most readily machinable of all the chromium-nickel stainless grades and has good corrosion resistance, although less than other chromium-nickel grades, such as 304 or 316. It is non-magnetic in the annealed condition and not hardenable by heat treatment. Tensile strength and hardness can be increased by cold working. Slight magnetism can be detected by cold working. 303 has excellent scale resistance at temperatures up to 1600Â° F in continuous service. It is manufactured by the electric-furnace process and meets the exacting requirements of the aircraft industry. 303 stainless steel is produced in rounds, rectangles, squares, hexagons, and in a BSQ round form; a bearing shaft quality ground and polished round to specific undersize tolerances to fit a bearing on a high quality stainless shaft.