Steel Ball Hardness

      BALL SIZE  →
   MATERIAL   ↓
BELOW 5.00 MM ABOVE 5.00 MM
AISI-E-52100 81 TO 85 HRA 60 TO 67 HRC
AISI-420 75 TO78  HRA 48 TO 54  HRC 
AISI 420 B 77 TO 79 HRA 52 TO 56 HRC
AISI-420C 78.5 TO 81 HRA 55 TO 60  HRC
AISI-440C 80 TO 83 HRA 58 TO 63 HRC
AISI S2 78 TO 81  HRA 55 TO 60  HRC

NOTE – HARDNESS CHECKED ON SPHERICAL  SURFACE AND READING ARE ADDED WITH CORRECTION
FACTOR AS PER ABMA STD. 10A.