Cast iron phase transformation 1

[MadDog88]

We have a cast iron fan hub which is stuck/corroded onto a alloy steel shaft. I would like to apply heat to the hub in order remove it from the shaft. I am aware of the the effect of heat on Q+T alloy steel but how will heat from an oxy torch affect the microstructure and physical properties of the cast iron? ie. will it be detrimental to future service.
Thanks

 

[arunmrao]

Try a low temperature heating. Any heating to red hot condition may cause the cast iron to crack also this would harden the cast iron. So slow heating and perseverance is the only choice.
Good Luck

 

[cv1]

Here's a trick that an old fitter told me. Drill in from the cast iron side and tap the hole. Connect a high pressure hydraulic oil line and pump in oil as best you can. After 24 hours (longer is better some times) you would be suppried just how easy the hub will slip off.

 

[rustbuster1]

It is perfectly OK to heat the gray iron hub to 500 - 600 C(slight redness) without any metallurgical effect - or GCI would not be widely used for stoves, etc. This should be hot enough to get it loose, especially if you keep the shaft from getting hot too.

 

[MadDog88]

Thanks for your help. We did manage to get it free witha bit more heat and a fair bit of force.