I. Rockwell Hardness (HR)
Principle Uses a diamond cone with a vertex angle of 120 degrees or a steel ball of 1.59mm or 3.18mm diameter as the indenter. Applies initial load and main load to indent the material surface. Calculates hardness value based on indentation depth. Deeper indentation means lower hardness value.
Characteristics：
Fast testing and easy operation, suitable for batch inspection.
Capable of testing medium to high hardness materials.
Multiple scales based on material hardness:
HRA: 60kg load with diamond indenter, for ultra-hard materials like cemented carbide.
HRB: 100kg load with steel ball indenter, for mild steel, copper alloys, aluminum alloys.
HRC: 150kg load with diamond indenter, for quenched steel, high-hardness alloys.
Typical Applications Widely used for rapid hardness testing of metal products such as cutting tools, bearings, gears, and cast iron parts.
II. Brinell Hardness (HBW)
Principle Uses a hard alloy ball usually of 10mm diameter to indent the material surface under specified load. Calculates hardness value based on indentation diameter.Common types:
HBS: Steel ball indenter, for materials with hardness ≤450 HB such as mild steel, gray cast iron, non-ferrous metals.
HBW: Hard alloy ball indenter, for materials with hardness ≤650 HB, the mainstream form of modern standards.
Characteristics：
Stable results and good repeatability.
Suitable for soft to medium hardness metals.
Large indentation, not suitable for thin-walled or small parts.
Typical Applications Hardness testing of raw materials and rough machined parts such as annealed steel, cast iron, non-ferrous metals and their alloys.
III. Vickers Hardness (HV)
Principle Uses a square pyramid diamond indenter with a vertex angle of 136 degrees. Indents the material surface under specified load. Calculates hardness value based on indentation diagonal length.
Characteristics：
High precision, capable of testing extremely small areas.
Wide application range, from soft metals to ultra-hard materials.
Minimal indentation, suitable for thin-walled parts, coatings, and micro-area testing.
Typical Applications Hardness testing of precision parts, coatings, and thin plates such as mobile phone shell coatings. Also used for micro-area hardness analysis like grain boundaries and phase boundaries in scientific research.
IV.Suggestions for Testing Method Selection
Production site and batch inspection: Choose Rockwell Hardness.
Raw materials and high precision requirements: Choose Brinell Hardness.
Coatings, micro-areas, and scientific research testing: Choose Vickers Hardness.
V. Summary
The three hardness testing methods each have advantages. Selection should be based on comprehensive consideration of material properties, specimen shape, hardness range and precision requirements to obtain the most reasonable test results.
