Examinations at the material 1.7076


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 air

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.  

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