440B stainless steel corresponds to the Chinese designations 7Cr17 (old) and 68Cr17 (new), and is a martensitic stainless steel. 440B stainless steel is magnetic, but generally (in air) it will not rust. 440B steel is harder than 440A steel and tougher than 440C steel. 440B stainless steel is used for cutting tools, measuring instruments, bearings, and valves. It is also suitable for bayonet blades. Performance: 440B stainless steel is harder than 440A steel and tougher than 440C steel.