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Material Reference · Hardness

Rockwell. Brinell.
Vickers. Shore.
Hardness scales.

Material hardness measures resistance to deformation. Different scales for different materials and ranges. Rockwell for metals, Shore for plastics/elastomers.

01 · Key principles

Key principles.

Rockwell C (HRC)

Hardened steels

Standard for hardened steels 20-70 HRC. Below 20 use HRB scale.

Rockwell B (HRB)

Soft metals

Soft to medium metals 0-100 HRB. Aluminum 50-95 HRB.

Brinell (HB)

Cast irons, soft alloys

Brinell for cast iron, copper alloys, aluminum. 80-650 HB range.

Vickers (HV)

All metals

Universal scale for hard or soft. Microhardness for thin films.

Shore A

Soft elastomers

Rubber, soft plastics 0-100. Pencil eraser 70 Shore A.

Shore D

Hard plastics

Hard plastics, hard rubber 0-100. Acetal 80 Shore D.

Knoop

Brittle materials

Microhardness for ceramics, hardened thin layers.

Mohs scale

Minerals

Geology scratch hardness 1-10. Diamond 10, talc 1.

Conversion

Approximate

Cross-conversion approximate. Each scale measures slightly differently.

FAQ

Why hardness matters?

Wear resistance, fatigue strength, machinability, cuttability. Harder = more wear-resistant but often more brittle.

Hardness vs strength?

Approximate correlation: harder materials usually stronger. UTS ≈ 3.45 × HB for steel. But heat treatment and grain structure also affect.

Measuring hardness?

Standard Rockwell tester for production. Vickers for lab precision. Portable hardness testers for field measurements.

Specifying hardness?

Specify scale + value + tolerance: "55-60 HRC". Or specify functional outcome: "wear resistant per X application".

Heat treatment affects hardness?

Yes — major effect. 4140 steel: 22 HRC annealed, 50 HRC quench-tempered. Specify heat treat condition.

Plastic hardness?

Shore A or D depending on hardness. Acetal 80 D, polyurethane 50-95 A range. Different scale entirely from metals.

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