Full definition
Hardness scale based on residual indentation depth under a defined load. Main scales: HRC (diamond cone, 150 kgf, heat-treated steels: HRC 20-70), HRB (steel ball, 100 kgf, soft steels and alloys: HRB 0-100). HRC 58-62 for tool steel; HRC 28-35 for transmission shafts. Standard: ASTM E18, ISO 6508. Most widely used hardness test in industrial practice.