Why does flux core wire give better penetration

[nash bap]

Mine is a low power welder 30-70 amps and I find that if I use .030 flux core wire compared to .030 solid wire with gas I can get far greater penetration. While a .030 solid wire shows very little penetration on 16ga sheet, the same size wire in flux core shows excessive penetration; both at the max power setting.

Could someone please explain why?

 

[shenion]

First reason is the gas: The flux burns some adding heat and shields the weld better. MIG gas tends to cool the weld pool. Adding more CO2 helps as it is an active gas.

The second reason is the polarity. 2/3 of the heat goes to the positive side; 1/3 to the negative. Gasless has the + side the work while gas MIG has the wire as the + side.

 

[nash bap]

Thanks shenion. Always a wealth of information!

I know that Mig wire welding with gas comes out lousy on the flux setting but can flux core wire be welded using the Mig setting?

Nash

 

[shenion]

Give it a try, some have said it works ok.

I have never tried it as I always use gas

 

[snowcat]

Hang on flux core primarily give better pen down to the smaller cross section, this gives it a different patten as it deposits "columnar"........ Don't forget flux cored wires "duel shields" are always used with a shielding gas, and on the same priority, and one of the very reasons for there use is deeper pen, Higher deposition rates and the ease of positional work....