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Dejavu 02-09-2005 05:53 AM

Strength of a flux core weld?
My budget lead me to purchase a flux core welder, and it has worked for the patching and light fab work I have done so far. My boys want to build a mini chopper and I need some feedback on the strength of the welds using flux core. The welds appear dirty; does the flux create inclusions that would weaken the weld? Or is this just an appearance thing? I can live with a patch falling out, but not a fall from a broken weld.

Centerline 02-09-2005 07:13 AM

This is a good question and I'm sure you're going to get differing opinions on this.

It's my understanding that the flux core welder uses the flux to purify the weld just as the gas is used to purify the weld when using a conventional mig welder.

The argument and where people have a difference of opinion as to how well the flux core wire actually purifies the weld. Some will say not well at all and others will say it does the job just fine. All I can do is relate my experience. I use a Lincoln weld pack 100 flux core welder exclusively and I've done everything from light sheet metal to 3/16" steel including frame work. From what I've seen the welds, although certainly not as pretty, are just as strong as a gas weld. I get good penetration and other than the spattering caused by the flux I can see no difference. I generally grind my welds to dress them up so the spatter doesn't bother me much.

That's my experience so if it was me, I wouldn't worry about it. Now I'm sure there are going to be some descending opinions coming.....


Dejavu 02-09-2005 09:08 AM

Thanks, I just needed some reassuring from a more experienced builder. I still might add gussets to some of the joints, just as insurance and so my wife can sleep nights.
Thanks again,

Bee4Me 02-09-2005 12:15 PM

I've had no problems with the weld's themselves,just butt ugly joint's. The gussets would be good insurance.
You know kid's. "OK, I'll hold the rope and you go and..........:eek:

oldred 02-09-2005 01:09 PM

Ok-my two cents,I would strongly recommend NOT using flux core! I have been a certified welder for well over 30 years and I have used flux core wire in the mining industry since 1968 in sizes from .030 to .120 and on metal ranging from thin sheet to over 14" thick. In my opinion flux core is not nearly as strong as MIG wire and the only reasons we used it in the first place was because it would weld OK outside in the wind where a true MIG was not practical and it made for faster repairs when strength wasn't a major factor. I would NEVER consider flux core for a critical weld such as a frame or ANYWHERE else a weld failure could cause an accident or injury. If you look at the material data sheet you will see a small amount of aluminum is used as one of the deoxidizers--need I say more? Have you considered Oxy/Acetylene welding? Works great on tubing,quite often homebuilt aircraft are welded using this method. If you have access to a true MIG welder or a stick using low hydrogen rods(e7018 or similar)you can do a simple test by tacking a small plate to a metal table top or another plate and then bending them untill they break. If both types of welds are done correctly the flux core will fail with a LOT less effort.

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