Cracking Welds
Cracking Welds
(OP)
I'm trying to find at what tempature change rate will cracks form in sound weld using E110C-K4 weld wire.
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RE: Cracking Welds
What's the base material? Welding process parameters?
Just for starters...
David Benson
Benson's Mobile Welding & Fabrication
www.bensonmobilewelding.com
RE: Cracking Welds
Let me know if there is any more infromation needed.
RE: Cracking Welds
Where are the cracks occurring, in the weld metal or base metal?
What direction are the cracks?
RE: Cracking Welds
RE: Cracking Welds
The cracks are only in the weld and they are mostly running transverse. I've seen as many as 4 in one 5' section of weld. And what really concerns me is that these are showing up approx 2 to 4 days after being tested clean at the initial process point using mag particle.
My theory is rapid cooling following the initial process is causing stresses to form and giving me these cracks.
RE: Cracking Welds
If what you describe is correct, these transverse cracks are more probably caused by delayed cracking from hydrogen in the weld. I would use low hydrogen electrodes immediately and if necessary, increase preheat and clean the weld joint before welding.
RE: Cracking Welds
Thanks I'll pass that on to the tiger team and see if these are things that they have looked at already.
RE: Cracking Welds
Normally cooling or restraint cracking will split the weld.
cola,
My spelling checker loves it.
RE: Cracking Welds
And no worries I give my spell checker a real work out. I've even had to update it with words after checking them online first. I can mis-spell anything if you catch me at the right time.
RE: Cracking Welds
You may need to replace this shipment of weld wire and purchse wire with the suffix designator H4, for low hydrogen. As an alterate approach conduct a post weld bake at 500-550 deg F for 30 minutes, immediately after welding and see if this helps.
RE: Cracking Welds
That's kinda hot. What's that going to do to my 12560?
RE: Cracking Welds
RE: Cracking Welds
I'll look into that, but due to our application there is a lot of skittishness about any high heat applications. I did confirm that our weld wire is the equivalent of H4.
thanks
RE: Cracking Welds
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Cracking Welds
What does equivalent mean? Either you purchase the solid core wire as low hydrogen with a suffix designator or you don't. By the way, I have rejected solid core wire on several occasions because of excessive dissolved hydrogen content from manufacture.
RE: Cracking Welds
The designator K4 according to TriMark is the same as a H4 designator. It has the same Hydrogen dissolution rate of less than 4ml/100g. Sorry I guess I stated that wrong in my previous post. I should have stated that the K4 designator on our weld wire is = to H4.
Sorry I want to make sure I understand this, you mean you've rejected the raw wire or did you reject products built with it due to bad welds caused by the use of this type of wire? And if you rejected the wire, do you mind me asking who the manufacturer was? If it's the same one we use I'll have an easy time of convincing the weld group to test the wire stock.
My next question, the current theory of our tiger team is that insufficent removal of tack welds is the main cause of the tranverse cracks. What do you think of this theory?
RE: Cracking Welds
I just looked at their typicals online, and it's interesting that their CWB designation includes H4 but their AWS designation doesn't. Typically a company won't include the H4 designation if they don't consistently get test results below 4 ml/100g; I've seen certs with a one-time diffusible hydrogen result of 3.8 and an H8 designation.
How were the tacks made and of what?
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Cracking Welds
RE: Cracking Welds
htt
No diffusible hydrogen result listed. You could call them and ask about it.
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Cracking Welds
Thanks again or all your help. You all pointed me in the directions and I was able to verify and rule out most material related causes.
RE: Cracking Welds
RE: Cracking Welds
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Cracking Welds
If the part is solidly braced at 2 ends, and welded between the 2 braces, and the braces are not flexible enought to longitudinally expand as the welded part expands ( during welding) , then the coolng of teh wled and HAZ will impose a high tenisle load that may crack a brittle weld.
RE: Cracking Welds
Let's say I was welding steel panels onto a square frame of tube steel by welding the steel plates together using the tube steel as a backer. If I weld both side panels to the top, front, and rear panels first and then come back and weld the top panel to the front panel between the sides, would the welded side panels give me the kind of bracing you are talking about here?
RE: Cracking Welds
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: Cracking Welds
....one must remove the source of hydrogen. If the cracking occurred during or immediately after welding, I could agree that fixturing could be a contributor regarding local tensile overstress condition. We seem to be going off tangent.