cracked welds

[Miles]

Good day,
I'm welding a piece of 1/2" X 6" strap five feet long onto another piece of 1/2" metal. It's a lap joint with 3" of the top piece overlaping the bottom piece. I drilled three 1/2" holes and bolted the two pieces together to hold in position untill I have finished welding. I made three welds about five or six inches long on one side of the plate. one on each end and one in the center.After I chipped the slag[scale??] off the weld I could see the weld had a hairline fracture running along the legnth. I turned the project over and welded three places on the other side. That side didn't show any sides of cracking. I turned the project over again and the three welds I'd made first were cracked the entire legnth of the weld.
Anyone know why that would be happening?
Thanks for any help.

[Big T]

I'm not a welder by trade but it could've been from stress. 1/2'' is pretty thick and if you had a small/thin bead that didn't have very good penetration it could've caused the crack. The first welds probably preheated the metal and allowed for better penetration on the other side. I know there's a lot of variables when it comes melting two pieces of metal together., different types of steel require different techniques and so forth. I know there's a few guys on here that are welders and they'll probably give you a better answer but this is all I've got.

[bairboy]

I'm a farmer so my welding is not professional but my opinion, my welds have never broke. I don't know what kind of welder you are using. I have stick feed, wire welder, tix and mig, everything except the stick is rested for no more than 1/4 inch. When I had welded thicker steel I find I can't get it hot enough. The thicker the steel the hotter I push it. I like to see a pretty head and see the steel melt together I like to weld in a 'U' motion I find on the thicker stuff it pulls the weld right around heating the steel and really fusing it. Thicker stuff I always use stick feed. When it's a job with not a big load depending on the weld I will use 6011 rod 7018 is stronger and more reliable. Thinner steel you use less heat cus it's easy to melt it all and burn holes into it but the thick stuff can take it. This probably don't help, but my welds have t let me down yet. My last weld job was removing a flat bed from a 25000 lb truck on the farm and mounting it to the new truck. Since it has a dump option there are only 3 welds around a triangle hinge which is the pivot my. No bigger than a foot all the way around. 7018 hot all the way.

[bairboy]

Sorry for the typos stupid auto correct on phones.

[Weldun]

Most generally weld failures (cracks) are the relsult of different material compositions being welded together with an improper filler material, pre heat or post weld heat. All "steel " is not created equally even though it all looks the same. Maganese,abrasive resistance and chrome moly all look about the same to the naked eye but all are very different animals when you try to join them. In the world of smoker building and such it's real easy to come across a piece of free steel that is something other than what it appears. As already mentioned if either e6010 or e7018 won't do the trick with a minimum ambient metal temp of 50 degrees Fahrenheit it's most likely material related.

[bairboy]

Weldun is probably right I've never had any issues with this. Good education

[Miles]

Thanks for the replies,
I checked with Lincoln Electeric, they also think too much heat and suggest I turn down the amperage and make more and smaller beads. The heat could be causing the metal to move creating the cracks. I'm not an experienced welder and I used a mig to make my reverse flow smoker. The 1/4" plate I welded in for the baffle plate took a lot of wire but most likely didn't put in the heat I am with this stick welder.

It is an A/C welder so the 6010 rod is not an option, I have some 6011 I will try.

It could be two different materials, the base is a cutting edge of a loader bucket, that may be hardened steel, but the rod is really undercutting that as well.

No night classes on welding on our little island so it's teach yourself, and ask for help wherever one can.
Thanks.

[Weldun]

I think you just found your answer, those cutting edges from buckets and blades are typically a harder material than standard carbon steel and yes multiple smaller stringer beads are better than one big wide bead since its induces much less stress as the weld cools. Sometimes peening between passes helps to relieve stress , I've also had some success with keeping my inner pass temp down (material temp between welds) by skipping around and welding different areas a little at a time. My only concern is if whatever your doing is going to be exposed to heat cycles the different enpansion rates of materials combined with the lack of elasticity in that hardened cutting edge your welds may be prone to cracking later on.

[Miles]

Holy spatter!
The 6011 rod burns down faster than the 7014 and spews spatter all over. Like using flux core wire. Undercuts more too.
I turned down the amps and got a nicer bead, didn't like the look of penetration so I raised it just a bit and things worked a lot better.I don't think the little amperage indicator arm on this old Spitfire welder is exactly accurate, or even close. I'm welding a Bobcat bucket so won't have to worry about temp swings. The thing was torn up so I cut out a lot of plate and welded in patches then welded doublers over top. I decided to put a 1/2" plate under the old worn cutting edge to give it some new life. That's when my problems really started.

I put 1/2"X2" straps on each side for side bits, I used the 7014 for one side and the 6011 for the other. I had better luck with the 7014 but the 6011 may have gotten more penetration.
I think I'll try some 7024 rod on my next project, if there is one.

Another issue I found was the stinger started to hum or vibrate as I was welding some longer beads. I could feel it in my hand. Any thoughts as to what that may be, or is that normal? It kind of felt like I was holding a piece of metal close to an electrio magnet, or passing a piece of metal close to an electric pump or motor. Maybe the old welder reaching it's duty cycle limit?

I'd like to get enough practice and trial and error welding done on ugly projects like this so I will be a bit better and faster for my next smoker build. I have my eye on a 200 gallon propane tank and there is a fellow with a few sheets of 1/4" plate that would be great for a huge chicken griller.

[Rodcrafter]

I'm going to bet it is the welder fluctuations of frequency. I believe it is time to get a real welder. Sorry for the way that sounds, I just hate to see people try so hard with the wrong equipment. That thing is maybe ok as a generator.


Making memories.

[Miles]

You're right about using tools not up to the job, but it's all I have and I can't find the money to get another. I understand DC welders are easier to use.
Won't work as generator as it plugs into the wall receptacle, just a big transformer. I got it a couple of years ago to make some repairs on my sawmill but I used the mig for that.

[Tom_Heath]

Find some 7018 AC rod and don't look back. They do make it, just can be tough to find sometimes. My opinion would be to run uphill at about a 45 degree angle and run as hot as you can without having arc blow. Force it to cool slow. A few passes with a torch works or could even be covered in sand to help sink the heat. Uphill 7018 is fun to run on heavy plate as you can really watch it work.


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[Squiggle]

Yep, 7018 low hydrogen is awesome, so easy to run a nice bead.

[Miles]

We wanted a bunch of bolts welded to a piece of grader blade so we could bolt it onto an excavator thumb when needed. The professional welder we took it to welded the bolts to a steel rod instead then bolted the rod to the blade through the attachment holes.He did the job well and also informed me when welding hardened steel such as cutting edges the metal has to be preheated and then welded when hot then kept hot for an extended length of time after in order to weld the two dissimilar metals together. Welding the bolts to the rod was a quick cheap job welding to the blade would have cost a bunch. I forget the times and temps.
I was definitely welding hardened steel to un hardened steel on my project, can't say it was the reason for my crappy welding skills but it may have contributed.

[Squiggle]

When you heat hardened metal it takes the hardening out of it, my mate makes knives in his forge & he's been teaching me about heat treating metals & what the different colors do to the metal when you heat it to different temps. When you weld stuff you see a rainbow circle around the weld & each colour changes the metal differently, blue makes it springy, yellow hardens it, & so on.