Welding help needed

[ronko]

Build logsplitter.
Cleaned out the back shed, put it all inna pile and welded it together.
Ground away everything that didn't look like a logsplitter.
7 1/2 facecords of knarly hickory later, my knife has torn loose from the 10 inch ibeam.
Knife was made of two 1/2 inch grader cutting edges, welded back to back.
Backup gussett is of 1 inch CRS that had laying around.
Welded together with Lincoln 225 buzzbox, 5/32 6013 set on 180 amp.
Gonna try to post a picture.
The CRS gussett held!
Weld is torn where it meets the harder (Grader Blade) steel and some right thru the center of the weld.
Gotta try ta get that puppy back offa there, regrind all way around, then open to suggestions as to where I went horribly wrong!

[Berniep]

It doesn't look so much torn as cracked all the way around. It has to do with the dissimilar metals. Many suppliers of wedges recommend welding with a low hydrogen rod. (I think 7018 is a low hydrogen rod) Or maybe preheating and cooling slowly.

There are a lot of welding experts on here and I am sure they will give good advice but you could also check out WeldingWeb™ - Professional Welding Forum - Powered by vBulletin they are a lot like this website, good people, good advice.

[Firehouse1302]

Hi,

It looks like you've encountered hydrogen induced cracking. As a general practice, the best way to avoid this condition is to preheat the area adjacent to the weld and then weld it in multiple passes. This will accomplish two things. 1. It will slightly anneal the fusion plane. 2. Multiple passes will minimize hydrogen diffusion. If you can, try to grind out as much of the filler material as you can, (v-groove if possible). Preheat the area to a dull cherry and then do a root weld with two more alternating passes over it to fill while it's still hot. Hopefully this will solve your problem. If you decide to try it, let us know if it holds up.

Thanks

[ronko]

Thank You Bernie and Firehouse.
Knew it was probably on account of the dissimilar metals but didn't know what to do about it. Will get back to grinding it off and also will try the link.
We thankyerbellymuch!

[bobodu]

Yep....I use 7018.There also seems to be some undercutting.

[ronko]

Thanks Bobbobodu
General concensus seem to warrant vgrooving, 7018, with preheating before , during and after letting cool slowly. Gonna also jack up each side so that can lay that puddle in there better to prevent undercutting.

[bobodu]

Looking at the pictures again after some coffee,I'm not sure I'm correct on the undercutting.Your settings on the welder should be good...I think it's the rod choice.I redid my wedge after the original got beat up pretty badly and took the easy route after bending many that I made outta stuff I had around.Went to the store and bought three splitting wedges and stacked them up on the end of the beam......pushed em right off!! Back to the store for some 7018 and they are still on the splitter after several cords of the nasty stuff the tree company left me.I also suggest making two root passes and one cap...build that sucker up...the log ain't gonna care!! I wouldn't jack it up either....

[bjcsc]

I think the majority of the problem was caused by only having one of the three passes you need there. On logsplitters I make, I weld the cylinder brackets (1" thick) and the foot (2" plate) to a 6" 25# beam with three passes. The first like yours, the second from the beam across ~2/3 of the first, and the last from the bracket/foot to the beginning of the second. Crude drawing attached...

[Egon]

Cutting edge welding usually requires a different rod than mild steel. Check with your welding supplier on the correct rod.

[allengentry]

Originally Posted by ronko

Build logsplitter.
Cleaned out the back shed, put it all inna pile and welded it together.
Ground away everything that didn't look like a logsplitter.
7 1/2 facecords of knarly hickory later, my knife has torn loose from the 10 inch ibeam.
Knife was made of two 1/2 inch grader cutting edges, welded back to back.
Backup gussett is of 1 inch CRS that had laying around.
Welded together with Lincoln 225 buzzbox, 5/32 6013 set on 180 amp.
Gonna try to post a picture.
The CRS gussett held!
Weld is torn where it meets the harder (Grader Blade) steel and some right thru the center of the weld.
Gotta try ta get that puppy back offa there, regrind all way around, then open to suggestions as to where I went horribly wrong!

I have a few questions and comments.

First of all, the scraper blades that you used were most certainly heat treated and hardened. Since you have already welded them cold, you have affected (likely ruined) the heat treatment. You have probably hardened them. Since you're only cutting soft wood, this really isn't an issue. But it's something to remember.

Secondly, preheating to a dull cherry is not a good idea. That is way too hot, Again, you'll affect the heat treatment. Preheat to 450*F max on your 1" material, somewhere around 350* for the 1/2" scraper blades. 1/2" material stacked does not equal 1" of solid, so preheat a little less. For a proper preheat, you have to know what the material is. If you don't safe numbers are 250-350*F for your thinner stuff, and 450*F or so for your thicker stuff. These are ballpark figures to help you more than hurt you. Mild steel requires a pre heat for material over 1" thick.

Your electrode selection was wrong. You want a lo-hy such as 7018 when welding alloy steels to mild steel. This will reduce the likelyhood of cracking, just as you got. Remember, when joining disimiliar steels, ALWAYS match the weaker metal.

As for utilizing a multi-pass process, I can not comment unless I know the thickness of the steel you are welding this knife/gusset to. If it is only 1/4" thick, you only need 1/8" of weld ALL THE WAY AROUND your knife, except the cutting edge. That said, 1/4" of weld all the way around is good. Your total weld should match your minimum thickness.

To further clarify, say your base is 1/4" thick. If you were only welding one side, you would need a 1/4" weld. Weld all around? 1/8". If it's 3/8 thick, 3/16" all around or 3/8" on one side. 1/2" thick? 1/4" all around or 1/2" on one side. Piling up 1" of weld on a thin base plate may give you a false sense of security, but you're actually overwelding and affecting your thinner material. Overheating, larger HAZ and so on.

Knock that thing offa there. Grind out all the filler you deposited with the 60xx rod you used, heat it up and re-weld with 7018. Also remember that with pre-heating, it will be much easier to undercut.

Hope this helps.

Allen