Higher measurements indicate harder materials. For rotary shafts, common Rockwell hardness ranges are 50 to 59, 60 to 69, and 70 to 79. The Brinell hardness test subjects a test material to a load of 3000 kg with a hardened steel or carbide ball that is 10 mm in diameter. The Knoop hardness test also measures a material’s hardness through its ...
