Heat Treatment Shrinkage
Heat Treatment Shrinkage
(OP)
Hi,
Is there a formula to allow for Heat treating shrinkage of an internal bore ?
I want to finish with a bore of 42mm in a billet (diam 123mm) of EN36 treated to HRc60.
Thanks
Richard
Is there a formula to allow for Heat treating shrinkage of an internal bore ?
I want to finish with a bore of 42mm in a billet (diam 123mm) of EN36 treated to HRc60.
Thanks
Richard





RE: Heat Treatment Shrinkage
If its going to be around 0.005mm (0.0002") then you need to jig grind or some such (ID Grind) anyway.
If its around 0.050mm (0.0020") then you can likely get close with a bit of trial and/or a bit of cutting with a carbide tool.
If its around 0.5mm (0.0200") then machine and heat treat and dont worry.
Some steels are better at this, and soem machinists can pull off a drawing note of MTS. (Make To Size)
Nick
I love materials science!
RE: Heat Treatment Shrinkage
There is no formula for this, because there are competing effects: growth due to martensite formation, shrinkage due to temperature reduction & tempering, and then the unknown of residual stress distribution in the bar/billet/machined component and what type of distortion will occur due to uneven temperature distribution during quenching. NickE gave some recommendations for how to account for this.
RE: Heat Treatment Shrinkage