Noob - flux core welds cracking.

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Hi everyone, I came on this site to pick your brains on how I could fix a bracket I welded for my Jeep, and prevent cracking again.This is a tow hook about 1/2" thick, and I welded on a 1/4" plate bracket for a grille guard. I made this in December 2013 and TODAY, I noticed cracks down the center of EVERY bead I laid on these.Picture from the day it was welded:Top view diagram:Today: some of the cracks are so bad that a piece of weld had fallen out!I used Lincoln EasyMig/MigPak 180, and 0.35 Lincoln brand flux core wire. Used the settings for 1/4", maybe I should have used a higher setting?I guess this is sort of a lap weld - I don't quite remember the details of how I did these, but knowing how impatient I am, I probably laid the second bead immediately after the first one. How would you approach this and how could I fix this?
Reply:Is that piece cast iron? Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:It's cast something.. not sure what - I have a spare bumper with other hooks in it I can perform and upload a spark test with. Lets assume for a moment that it IS cast iron - how would that make the bead itself crack down the middle? Different expansion/contraction rate causing stress on the weld?
Reply:Inclusion. Faulty core in the flux core causing crystallization in the filler metal(s) ?Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:hmm, I used a brand new 10lb spool, and my other (smaller) welds turned out fine. The only welds that cracked on this whole project were these 4 beads I laid on this pair of tow hooks. The inner bead (weld#2) have greater separation than the outer ones
Reply:How heavy is grill guard?  If the weld feel out then it didn't have good penetration or it wasn't compatable.
Reply:Originally Posted by efm-7knowing how impatient I am, I probably laid the second bead immediately after the first one.
Reply:the grille guard is not too heavy, maybe 20lbs? the weld didn't "fall out" the edges are still fused to each side.it cracked down the center of the bead and some places, the crack split I two and whatever weld was between that, fell out. Probably extra information I shouldn't have added in.
Reply:Originally Posted by asdfDid you remove flux before the second weld? That might be some of the problem, but the "is it cast?" question adds a load of variables.
Reply:Maybe I needed to peen it
Reply:Besides cast iron, there are things that the E71T-G, GS or -11 just won't weld well without what amounts to center line cracking. Brake drum materials, grader blade cutting bar materials, rail road rails and/or tie plates. I imagine those are all high carbon high alloy materials. Someone can no doubt explain which groups these would be. These are just a few I know from personal trial and fail."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:it's almost starting to look like I need to make my own tow hooks out of a metal of my choice
Reply:D2 machined. 40 rc. Bolted on4140 HT and 5160 will work................Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:I run into this all the time with farm equipment, a lot of parts are cast steel .  Fc is terrible on cast steel...just won't work well.  Pre-heat to 300 degrees , weld with 7018, and post heat slowly down below 200 degrees.   Just dealt with this last weekend on an old john Deere disk part.Farmer2Hobart Champion EliteMiller S-32p 12Lincoln sp175tLincoln 225 ac tombstoneHarris oxy/aceteleneMakita grinders/chopsawHypertherm Powermax 45
Reply:Originally Posted by efm-7the grille guard is not too heavy, maybe 20lbs?
Reply:file some off the cast. spit on the dust you've just filed off.Does it now smell like rotten eggs? That's sulphur.Sulphur is the main culprit of centerbead cracking.
Reply:Originally Posted by walkerweldSomeone says "She's so heavy"  Does that mean she is as fat as a butterball or a very intellectual person?
Reply:Originally Posted by kingnerofile some off the cast. spit on the dust you've just filed off.Does it now smell like rotten eggs? That's sulphur.Sulphur is the main culprit of centerbead cracking.
Reply:Originally Posted by kingnerofile some off the cast. spit on the dust you've just filed off.Does it now smell like rotten eggs? That's sulphur.Sulphur is the main culprit of centerbead cracking.
Reply:Originally Posted by kingnerofile some off the cast. spit on the dust you've just filed off.Does it now smell like rotten eggs? That's sulphur.Sulphur is the main culprit of centerbead cracking.
Reply:I would like to put in my 2 cents.From the pictures it doesn't look like there is a very good heat signature where you welded. Also, I have welded tow hooks before and they are very hard material, best to grind off the hard casing on the hooks before welding. It's also good to pre heat and weld them with a stick welder with 7018. If I was doing a job like this I would tack everything together and put the pieces in my grill and get them nice and hot, pull one out and weld it but leave the other in the grill until your ready to weld it.In my experience stick welding tow hooks works best with 7018.They are probably cast steel, cast iron would be to brittle to take the stress of a tow hook.Last edited by kctgb; 04-23-2014 at 06:27 PM.
Reply:Originally Posted by walkerweldSomewhat related sideline to the above.  If you make it a habit to spit on the handles of your hand tools and such, while other people are watching.............they will leave your stuff alone.  Especially effective if you dip or chew tobacco.
Reply:Are you getting frame flex/twist??....Do you need to use rubber grommets on your guard mount with dowel pins??
Reply:Originally Posted by stetsonAre you getting frame flex/twist??....Do you need to use rubber grommets on your guard mount with dowel pins??
Reply:Okay, finally ripped got a chance to get closer pics..
Reply:while grinding off the old weld, it did smell sulfuric