Discussion:
Part movement when welding Titanium?
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"D"
2015-01-05 15:00:19 UTC
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Hi Gang,
Long time no post, been busy.
How much, if at all does Ti move after welding?
Customer wants finished parts to weld together and is expecting to not have to machine after welding.

T.I.A.
F. George McDuffee
2015-01-05 15:18:33 UTC
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On Mon, 5 Jan 2015 07:00:19 -0800 (PST), "\"D\""
Post by "D"
Hi Gang,
Long time no post, been busy.
How much, if at all does Ti move after welding?
Customer wants finished parts to weld together and is expecting to not have to machine after welding.
T.I.A.
====================
Need more information. Will the parts be jig welded or
"freehand?" Thick to thin sections? Amount of weld, i. e.
tack or full extended bead? What are the tolerances and end
uses? Post weld stress relief?
--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"
"D"
2015-01-05 18:07:02 UTC
Permalink
Post by F. George McDuffee
====================
Need more information. Will the parts be jig welded or
"freehand?" Thick to thin sections? Amount of weld, i. e.
tack or full extended bead? What are the tolerances and end
uses? Post weld stress relief?
<Snipped>
Parts will be pinned together.
About 1" of bead 2" apart, 2 places on each side of 4" long X 1.4" wide part.
Same thickness, give or take .06, at 1/4" thick.
No post stress relief unless needed.
+/-.005 tol.
Cannot state end use.

Thanks for your time!
F. George McDuffee
2015-01-05 20:03:28 UTC
Permalink
On Mon, 5 Jan 2015 10:07:02 -0800 (PST), "\"D\""
Post by "D"
Post by F. George McDuffee
====================
Need more information. Will the parts be jig welded or
"freehand?" Thick to thin sections? Amount of weld, i. e.
tack or full extended bead? What are the tolerances and end
uses? Post weld stress relief?
<Snipped>
Parts will be pinned together.
About 1" of bead 2" apart, 2 places on each side of 4" long X 1.4" wide part.
Same thickness, give or take .06, at 1/4" thick.
No post stress relief unless needed.
+/-.005 tol.
Cannot state end use.
Thanks for your time!
===================

Much will depend on the ti alloy and welding conditions, e.
g. stable/warm room temperature with no drafts, parts stored
overnight to equalize temperature, low heat conductivity
welding support [not steel table], and skill of welder, i.
e. gas flow, rod size and amps.

As these are ti parts, with an end-use which cannot be
disclosed, you may well be using GDT true position
tolerances http://tinyurl.com/p2vrmo3, which can amplify
certain problems.

IMNSHO +/- 0.005 over 4 inches, particularly if this
involves flatness/squareness, may be problematic. One thing
that could be helpful is to minimize uneven cooling by
burying the parts in lime or mica immediately after welding.

I would certainly first try welding to see how it goes.

One thing that could help if there is a problem is to
fabricate a jig or fixture to hold the parts in the correct
alignment avoiding any stress on the [area around the] pins,
and keep the parts in the jig/fixture until these are cool.
[Fixture should be warm/hot to avoid chilling weld] This is
most practical for prototype or very low production.

One thing to check is adhesive bonding rather than welding.

Is this to be an xray, ultrasound or zyglo checked weld, and
will the welder have to be certified?
--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"
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