Re-temper aluminum street light poles

[greencircle]

This is in reference to pole production (aluminum street light pole welding to a cast aluminum base).
Generally post welding the pole weldment is subjected to precipitation hardening.

As you all may know this heat treatment is utilizes expensive setup with Large oven for enclosing complete pole, Time consuming etc.

I want to know your thoughts about induction heat treatment. This is a much localized heat treatment approach that doesn't need huge enclosures/equipment. I was thinking induction hardening was only applicable for magnetic materials like steel. Not sure how, turns out even aluminum can be heat treated.

My intention is to bring the temper back to T6 in the HAZ on the welded pole assemblies after this process.

Thoughts?

 

[CoryPad]

Induction heating only requires electrical conductivity, so nonferrous metals work too.

I think your proposal is not easy to do. Aluminum heat treatment (solutionizing, quenching and artificial aging) requires long times compared to steel heat treatment (austenitizing, quenching and tempering). This makes induction heating less suitable.

 

[greencircle]

Hi Corypad,

Thanks for your input. I am in agreement with you. Currently I am not sure of the cycle time with induction heat treatment. I have started discussion with couple of suppliers, it's still with sales guys. As usual sales guys are promising that it's a great solution. With some more questions and answers session I can be in a better solution to conclude.

By the way thus topic is discussed in another thread
thread404-377024. So, please join us there if you have any other point of view.

 

[tbuelna]

I did not see any description of the aluminum alloy used for the base casting. Is it correct to assume it is some sand casting alloy that is heat treatable and can be fusion welded?

I would also agree with CoryPad's comments regarding HT of large aluminum weldments using induction heating. Given the HT requirements of the aluminum alloys likely used, the high thermal conductivity of aluminum materials, and the section thickness at your weldment HAZ, you might need the induction heater to heat the weldment for an hour or more.

The attached chart giving HT soak times vs. section thickness for wrought aluminum materials might give you some insight.