A.Material Hardness Values
Hardness
Value HRC
Hardness
value HRB
Hardness
Value
Vickers
Hardness
Value
 Brinnell
N/mm2Symbols DIN
-2067114114400C15  
-974131131460C10  
183154156560C40stainless 303 
1090183182635   
1593199200680C5542CrMo432CrMo12
209722122476034CrNiMo6 14NiCr14   
2510125024985034CrNiMo6 pretreated   
30105278276955   
351093203231110    
401123853701270   
451154604271453 C40
hardened
  
50118535497167034CrNiMo6 
hardened
32NiCrMo45
hardened
42CrMo4 hardened
55  6395451870C35 hardened   
57  6945761940   
60  746601211014NiCr14
hardened
C10
hardened
 
63  867652222032CrMo12
nitrited
  
65  9406822300   
67  10607252400   
70  11707602640   

B. Material Hardness ( Heat Treatment )

The following table shows the different processes used in the heat treatment of gears
Material
Carburizing
Hardening
temperature
Quenching
method
Hardness
level
obtained
Tempering
Quenched
C40 830/860ˇăC
Hold at 210 to 230ˇăC
in an oil bath for
1h/25 mm
40-45 HRc
Hold at 650ˇăC
+ Cool for one hour
in an oven or in the open air
C55 810/840ˇăC
Hold at 210 to 230ˇăC
in an oil bath for
1h/25 mm
40-45 HRc
Hold at 650ˇăC
+ cool for one hour
in an oven or in the open air
42CrMo4 860/890ˇăC
Hold at 210 to 230ˇăC
in an oil bath for
1h/25 mm
40-45 HRc
Hold at 690ˇăC
+ cool for one hour
in an oven or in the open air
34CrNiMo6 820/850ˇăC
Hold at 180¨¤200ˇăC
in an oil bath for
1h/25 mm
40-45 HRc
Hold at 650ˇăC
+ cool for one hour
in an oven or in the open air
Cementation
C10<Ø100
Hold at
900 to 930ˇăC
for 1h
cementation depth 0,2mm
770/790ˇăC
Hold at 
150 to 200ˇăC
in an oil bath
1h/25 mm
55-60 HRc
Hold at 650ˇăC
+ cool for one hour
in an oven or in the open air
C10>Ø100
Hold at
900-930ˇăC
for 1h
cementation depth 0,2mm
900/930ˇăC
Hold at 150 to 200ˇăC
in an oil bath
1h/25 mm
57-62 HRc
Hold at 650ˇăC
+ cool for one hour
in an oven or in the open air
12NiCr14
Hold at 900-930ˇăC
for 1h
cementation depth 0,2mm
820/840ˇăC
Hold at 150 to 200ˇăC
in an oil bath
1h/25 mm
57-62 HRc
Hold at 650ˇăC
+ cool for one hour
in an oven or in the open air
*Do not stock or use at temperatures between 250 and 450ˇăC
All values are approximate