The series of experiments was made to get knowledge about
the hardness acceptance and crystalline structures at the material 32CrB4. The
following samples were axamined :
1. at a too low quenching temperature (alpha-gamma mixed area)
2. at too short holding times
3. at exact parameters
Initial condition : hot rolled 16,00 mm , spheroidised
Heat treatment : laboratory furnace (volume 5 liter) ; soaking
of the samples in 5 minutes
Hardening : holding time 30 minutes , quenching in oil
Tempering : 580° C , holding time 60 minutes , cooling at
More or less big quotas of undissolved carbides are existing
in the microstructure due to the lower diffusion speed at low temperatures and
into dependence of the limit of solubility of the austenite for carbon. At temperatures
below Ac3 (alpha-gamma mixed area) more or less big quotas of ferrite are existing
in the microstructure. A too low holding time causes an insufficient austenitization,
inadequate soaking and leaves larger remains of the original initial structure.
Delays at the cooling can lead to unwanted preeutectoid precipitates of ferrite.
All micrographs are from the core area of the samples.