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Cracking Welds
5

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.

RE: Cracking Welds

Not enough information to even attempt answering the question.

What's the base material?  Welding process parameters?

Just for starters...

David Benson
Benson's Mobile Welding & Fabrication
www.bensonmobilewelding.com

RE: Cracking Welds

(OP)
Base metal is 12560 with a A653 galvanized sheet steel backer. Beveld groove weld. Process is GMAW Pulse.

Let me know if there is any more infromation needed.

RE: Cracking Welds

For starters get rid of the Galvanized backer. This eliminates the possibility of any liquid metal embroilment.

Where are the cracks occurring, in the weld metal or base metal?

What direction are the cracks?

RE: Cracking Welds

While typos are standard part of writing on this form, I gotta love the liquid metal embroilment (you mean embrittlement) -metal cooked in liquid metal.   smile

RE: Cracking Welds

(OP)
uclesyd I've been trying to get rid of that stupid galvanized backer since I got on this project, but it's not going away. We do prep the backer by grinding it to remove some of the galvanized first and we are usuing a root pass and cover pass weld.

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

QSRW4;
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

(OP)
metengr,

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

In reference to the post by meteng I would open a new can of electrodes to use for testing.
Normally cooling or restraint cracking will split the weld.

cola,
My spelling checker loves it.

RE: Cracking Welds

(OP)
I can get them to throw a new spool of the metal core wire on the machine for this but since all that stuff is packaged in cardbord I don't think one wheel is going to differ that much from another. And since the welds I'm having cracks in are welded by diffrent opporators on diffrent machines I'm not sure a new spool of wire will help much.

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

QSRW4:
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

(OP)
metengr,

That's kinda hot. What's that going to do to my 12560?  

RE: Cracking Welds

I doubt that the base material was originally tempered at or below 600 deg F. So, I would not see any adverse effects on base material properties with a post weld bake to remove hydrogen.

RE: Cracking Welds

(OP)
metengr,

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

If it's metal-cored, it shouldn't be all that hygroscopic and the cardboard cartons are probably ok, so that's probably not it.  Not that I have anything useful to add about what probably *is* it.

Hg

Eng-Tips policies:  FAQ731-376: Eng-Tips.com Forum Policies

RE: Cracking Welds

QSRW4;
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

(OP)
metengr,

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

K4 is not equivalent to H4.  K4 is a reference to the alloy forumulation.  H4 is an independent part of the designation that would get tagged on to the end.  So either it's EC110-K4-H4, or it's just plain EC110-K4.  The manufacturer's cert should say which.

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

(OP)
I'll have to get someone to get me a copy of the certs. The tacks were made by the same wire. I'm really not happy to hear that the results of some of the test were higher than the 4 ml/100 g that they claim in the MSDS. I was hoping we were already using the right wire.

RE: Cracking Welds

(OP)
Thanks HgTX. In fact as soon as I got the CoC from my reciving department I did call them and confirmed that the metal core E110C-K4 is a H4 wire. The lab suporvisor I talked to wasn't sure why they don't put the H4 on the designator for that wire like they do others. Also someone within my company has already tested and confirmed the wire we have is good to all of our specifications. The bad tack welds are coming to the top of the list as our root cause which really means operator error.

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

Please let us know when you get the Root Cause as I've never experienced or heard of a bad tack undergoing delayed cracking.  Not to say it couldn't happen, but ever tack failure I've experienced happened on coll down.  

RE: Cracking Welds

Something to watch out for in future projects with this wire--if your client or the spec you're working to specifically requires H4 and it's not on the cert, a call to Joe O'Leary in Ashtabula won't suffice.

Hg

Eng-Tips policies:  FAQ731-376: Eng-Tips.com Forum Policies

RE: Cracking Welds

Its a wild shot, but sometimes the method of bracing the part to be welded can impose boundary conditions that will cause a weld to  crack.

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

(OP)
Dave,

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

Depends how flexible those side panels are and whether they can bend enough to accomodate the shrinkage of your last weld.

Hg

Eng-Tips policies:  FAQ731-376: Eng-Tips.com Forum Policies

RE: Cracking Welds

If this is truly delayed cracking as stated by the OP,

Quote:

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.


....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.
 

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