What is the time gap between carburising and hardening

[harsuda]

I carburise the material (EN36 C and AISI 9313) at 920 deg C. and cool it to 700 deg. C in the furnace and unload to cool it to room temperature in air. After this the material taken up for hardening and tempering. I want to know is there any specific time interval within which the hardening should be carried out after carburising to avoid resudaul stresses. Will these residual stresse effect the machinability?

 

[swall]

Once you reharden, you will end up with a new residual stress distribution resulting from the oil quench and final temper. The stress distribution from the carburize and slow cool cycle will be competely wiped out. Residual stresses will not affect machinability, only the dimensional accuracy after machining.