Welding crack

Welding Techniques, Theory, Machines and Questions.

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Sandun
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Welding crack

Post by Sandun »

Hi , friend , why welding cracking :(
Yesterday i weld (arc welding ) some iron plate 5mm , today i see they crack .
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warmstrong1955
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Re: Welding crack

Post by warmstrong1955 »

Without knowing what the plate is, or the wire:
You're runnin' too hot.
That's causing you to travel too fast.
And that's causing the weld to be much wider than its depth. Width & depth should be about the same.

I see a lot of spatter too. The rust I see is probably one of the causes for that.
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Sandun
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Re: Welding crack

Post by Sandun »

I use 6013 rod , 150 A , the plate 5 mm , is it wrong ?
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warmstrong1955
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Re: Welding crack

Post by warmstrong1955 »

Is your machine AC or DC? And what diameter is the 6013 you are using? 150 amps is hot if it’s 1/8”, extremely hot if it’s 3/32”.
6013 works well with AC machines, but is a poor choice for penetration, and that looks like part of your problem.
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NP317
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Re: Welding crack

Post by NP317 »

Perhaps use a 6011 rod for better penetration?
RussN
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warmstrong1955
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Re: Welding crack

Post by warmstrong1955 »

NP317 wrote: Tue Mar 28, 2023 10:36 am Perhaps use a 6011 rod for better penetration?
RussN
Definitely, and a much better choice with a crackerbox, than 6013.
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Russ Hanscom
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Re: Welding crack

Post by Russ Hanscom »

Depending on the parent material, a little preheat always helps,
Sandun
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Re: Welding crack

Post by Sandun »

It is 3/32 ( 2.5mm ) rod , and i use DC plant ( inventer type ) , I try 90 A but it sticks rod - what is the good , 130A , 140A ?
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warmstrong1955
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Re: Welding crack

Post by warmstrong1955 »

150 amps is above what you would run 1/8” 6013.
If you welded a full stick of 3/32” at 150 amps, it would start to glow red when about 1/2 the stick is used up.
Your weld looks to be too hot, and traveling too fast. Starts out OK, but as the metal your welding heats up, you started moving faster.

With a DC machine, 6010 or 5P is what I would use. The ‘P’ in 5 P stands for pipe, and it’s a good penetrating rod, unlike 6013.
Make sure you’re running DC reverse. (electrode positive)
Numbers on welders are only an indicator, and vary from one to the other. Can’t run at 90? Try 100. The weld is what tells you whether to turn the amps up or down, not the numbers on a dial. Grab some scrap plate and play.
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liveaboard
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Re: Welding crack

Post by liveaboard »

That's far too much current for a 2.5mm rod.
I'd use 3.2mm for 5mm plate, and about the same current.
Your base material might be the problem if it's not mild steel.
318J
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Re: Welding crack

Post by 318J »

Iron (if it's really iron, not steel) is generally not weldable. You can get away with welding wrought iron using a 60xx electrode, but it will crack without pre and post heating and a gentle cool down.

Agreed it appears to be running too hot, which will contribute to these issues. You'll have to learn to feel how hot is too hot, and how cold is too cold rather than what the machine says. 150amps is nearly double what I would run on an 1/8" 6010/6011 rod.

The problem isn't just with the heat though, when welding you want to use an electrode similar in composition to the base material. That's why they make nickel-iron electrodes for iron. Welding it with a steel electrode is a pinch-hitter method that will yield mixed results.
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Harold_V
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Re: Welding crack

Post by Harold_V »

318J wrote: Mon May 08, 2023 8:34 pm Iron (if it's really iron, not steel) is generally not weldable.
My comment is not intended to be controversial, but educational.

What you said is true of "cast iron" (white or gray), but it is not true of iron. Iron is available that is weldable without issue by conventional means but it is generally confused with steel. Think of the laminations in motors and transformers. They are carbon free iron.

H
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