BRUSH CASTING ALLOYS 20C AND 20CT are beryllium copper alloys (1.90-2.15% Be) of very high strength with cobalt as the second alloying element (0.35 to 0.70% Co). Use is in the age-hardened temper. Brush casting alloy 20CT is the fine-grained version. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on casting, heat treating, and machining. Filing Code: CU-581. Producer or source: Brush Wellman Inc.