Induction Hardening Cracks

[mdighe]

Hi
I am in process of analyzing cracked gears that were induction hardened. I have still not looked at the actual part but based on the process info I have received, I found the following to be of significane

1] Some overheating during induction heating
2] There was no stress releif done on these part before heat treating. The parts are huge and weigh about 1500 lbs. Also heavy machining was done on forged blanks.

Can high machining stresses actually cause cracking during induction heating? I have never (not yet) come across cracking due to residual stresses.

Any tips suggestions will be of great help.

Thanks

 

[Carburize]

Two areas to look at
1) Overheating of edges - typically ALL the corners should have a radius of at least 1/8-inch
2) Residual stresses - either from prior machining operations or from the I/H process - on large gears it is typical to stress relieve before I/H and to also include in-process stress relief operations.