Hardening blade blanks in the tunnel conveyor furnace

The soft annealed (Rockwell C scale hardness 20) carbon steel blade blanks are sawn to length from bars of rolled steel. Then they are carefully placed on the tunnel furnace conveyor where they are heated and held at about 1850 degrees Fahrenheit.

Hardness and
time at temperature
Austenitizing temperature ºF
Soaking time, minutes
Hardness after soaking, before tempering
1800
40
57
1850
30
60
1920
20
60
Soaking time is the time at temperature after the steel object is heated completely through. The knife blanks are about 1 cm ( 0.4 in.) thick so they heat through rapidly.
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