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