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Results 1 to 5 of 5
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29th May 2014, 08:00 PM #1
Senior Member
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- Feb 2013
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- Laidley, SE Qld
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Swaging 1.5" stainless steel tube
I need to increase the ID of the end of a piece of 1.5" x .0625" wall (1.375" ID) stainless steel tube to 1.65". The tube is 900 long, the swaged section is 40 long. I was going to make the appropriate tooling, heat the tube red hot and pull the tool into the tube.
I reckon that should work. Any thoughts or comments before I start?
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29th May 2014, 09:22 PM #2
The problem with heating the tube to red hot for any length of time is that you run the risk of removing the chromium content in the area if the temperature is too hot for too long and the area then loses it's corrosion resistance. You would then need to pickle and passivate the area to restore the corrosion protection. It's the reason why we minimise the heat input when TIG welding stainless.
What grade is the stainless? For 3xx grade steels the temperature at which intergranular corrosion begins is around 900F or 500C and red heat is above that.
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29th May 2014, 09:40 PM #3
Senior Member
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- May 2012
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- Kimberley, West Australia
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- 139
Tube expander
Hello Bob,
Do you have any spare length to experiment with? Worth asking your local exhaust shop to try their tube expander on a piece and see how it performs. They routinely fit SS tube to car systems and may have the answer waiting for you. Combustor.Old iron in the Outback, Kimberley WA.
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29th May 2014, 11:19 PM #4
GOLD MEMBER
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- Sep 2010
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- Lebrina
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Definitely do no heat the tube. I reckon you will cause more problems than you solve.
It is a fair increase in size that you are looking at, but using annealed tube it may be possible. I have expanded SS tube cold using a machined slug and a press and even made rectangle to round transition pieces the same way.
What are you actually building? There may be an alternative method.
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30th May 2014, 02:54 PM #5
Senior Member
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- Feb 2013
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- Laidley, SE Qld
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- 368
Thanks guys. I did what I should have done first up, ie talk to the stainless steel exhaust guys who expand tube every day. They reckon that the stretch I want to do may or may not work, the tube may split, it may not.
So off to plan B whatever that is.