TWI Industrial Member Report Summary 57/1978
By G R Salter and K R Spiller
A comparison has been made of the production performance of the manual gas-shielded arc processes commonly used for welding aluminium alloys.
The processes examined included argon-shielded AC TIG-welding, helium-shielded DC TIG-welding, argon-shielded pulsed MIG-welding, and conventional MIG-welding with argon, helium, or helium-argon shielding. These were used as appropriate to make butt and fillet welds in a commody used Al/Mg alloy of 3.2 to 25.4mm thickness and the results expressed in terms of output rate and tolerance to joint fitup.
The investigation did not include an assessment of the mechanical properties of the welded joints or the effect of welder skill. The results indicate that the main advantage of argon-shielded AC TIG welding is the control obtained when welding thin material and joints of variable fitup. Helium DC TIG-welding has specific advantage in the deep penetration welding of butt joints in the flat position.
Welding with the MIG processes under argon, argon-helium, or helium shielding offers output rate advantages when high metal deposition rates are required. The 70%He 30%Ar mixture was found to provide a combination of high joining rates with good controllability.