Inconel 625 Cold Working 2

[Cloya14]

All,

Currently in our shop we are heating 1/2" diameter 0.065" wall tubing filled with a magnesium oxide to 1600 Deg. F then rapid water quench to prevent cracking during bending. The inner radius of the material when bent is a 3/4" inner radius. We are currently having issues with cracking during bending process and i am trying to figure out what are the best options to get the softest material from heat treatment. Would a full solution quench and anneal be my best bet in achieving the softest material for bending? I might have forgot some details but thank you everyone in advance.

 

[metengr]

Would a full solution quench and anneal be my best bet in achieving the softest material for bending?

Yes.

 

[Cloya14]

Am i correct saying solution anneal temperature is from 2000-2150 Deg. F and then followed by a rapid water quench?

 

[EdStainless]

You don't need a water quench. Given the thin walls that you are dealing with this tube will air cool plenty fast.
Don't you buy the tube?
Order it solution annealed, and set a max yield strength and min elongation.
Your heating to 1600F may be lowering the ductility.
Given that the centerline of your bend in 1.25", which is only 2.5x the tube diameter. This is tight but should be doable.
Are you sure that you don't have them filled too tight? When you bend you get some ovaling of the tube and some thinning of the outer wall.
You need both of these, you can't make a tight bend without allowing some oavlity.

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Plymouth Tube

 

[Cloya14]

Thats a great suggestion ill need to get with my purchasing group to get a max yield strength and minimum elongation requirements added to any inconel 625 tubing we order. We do order it solution annealed but we then again anneal it to develop an oxide coating on the outside of the tube for better corrision resistance(thats what i was told it was for i didnt develop that process). Does annealing the tube to develop an oxide on the outside sound foreign to anyone else?

 

[tbuelna]

Where are the cracks occurring in your bent tube? What technique are you using to bend the tube? Are you roll forming the tube over a die using an internal mandrel?

A CL bend R of 2X the tube OD is pushing things a bit with 1/2" x .065 wall tubing. Also, what is the included angle of the bend?

 

[EdStainless]

If you anneal in air you will develop an oxide, and you will significantly DECREASE the corrosion resistance.
The Cr that is tied up in surface Cr oxides is not available to help prevent corrosion resistance.

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Plymouth Tube