Key principles.
Hardened steels
Standard for hardened steels 20-70 HRC. Below 20 use HRB scale.
Soft metals
Soft to medium metals 0-100 HRB. Aluminum 50-95 HRB.
Cast irons, soft alloys
Brinell for cast iron, copper alloys, aluminum. 80-650 HB range.
All metals
Universal scale for hard or soft. Microhardness for thin films.
Soft elastomers
Rubber, soft plastics 0-100. Pencil eraser 70 Shore A.
Hard plastics
Hard plastics, hard rubber 0-100. Acetal 80 Shore D.
Brittle materials
Microhardness for ceramics, hardened thin layers.
Minerals
Geology scratch hardness 1-10. Diamond 10, talc 1.
Approximate
Cross-conversion approximate. Each scale measures slightly differently.
FAQ
Wear resistance, fatigue strength, machinability, cuttability. Harder = more wear-resistant but often more brittle.
Approximate correlation: harder materials usually stronger. UTS ≈ 3.45 × HB for steel. But heat treatment and grain structure also affect.
Standard Rockwell tester for production. Vickers for lab precision. Portable hardness testers for field measurements.
Specify scale + value + tolerance: "55-60 HRC". Or specify functional outcome: "wear resistant per X application".
Yes — major effect. 4140 steel: 22 HRC annealed, 50 HRC quench-tempered. Specify heat treat condition.
Shore A or D depending on hardness. Acetal 80 D, polyurethane 50-95 A range. Different scale entirely from metals.
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