The 300 series stainless steels are classified as austenitic and are hardenable only by cold working methods. These grades of stainless have approximately 18% to 30% chromium and 6% to 20% nickel as their major alloying additions. This series of stainless steel alloys are known to resist corrosion while maintaining their strength at high temperatures. While the 304 grade is the most widely used alloy of all stainless steels, the 300 series grades are inventoried in stainless steel plate, sheet, bar, pipe, tube and fittings and much more.