The industry story about the O2 in Argoshield is that its not an addition, its simply too expensive to completely remove all the O2 so they list it as an advantage. Ive never heard this denied. You can get high purity Argon but it is much more expensive.
The Oxygen affects the weld metal in much the same way as the CO2, in fact a common rule of thumb is that 1% O2 produces the same effect as 3% CO2.
What they do is reduce the surface tension of the steel allowing it to flow better and wet at the edges where the weld meets the plate. I usually relate it to adding fairy liquid to water, it makes the water spread rather than blobs.
The steel used for "normal" MIG wire contains approx 0.7% Silicon and 1.4% Manganese. The Mn helps to increase the strength and the ductility of the steel. The Silicon protects the Manganese and soaks up Oxygen so that your weld isnt porous. Silicon also helps to weld metal to flow.
If you use an active gas you will burn out quite a bit of the Silicon and some of the Managanese resulting in a weld metal thats a bit softer and weaker. The black glassy slag on the weld surface is largely SiO2.
Some of the cheap MIG wires use low quality steel that is low on Si and Mn. The price is related to the alloy content. This makes the steel weaker, the resultant weld weaker and as it reduces the stiffness of the wire it also makes it more difficult to feed.
The Oxygen affects the weld metal in much the same way as the CO2, in fact a common rule of thumb is that 1% O2 produces the same effect as 3% CO2.
What they do is reduce the surface tension of the steel allowing it to flow better and wet at the edges where the weld meets the plate. I usually relate it to adding fairy liquid to water, it makes the water spread rather than blobs.
The steel used for "normal" MIG wire contains approx 0.7% Silicon and 1.4% Manganese. The Mn helps to increase the strength and the ductility of the steel. The Silicon protects the Manganese and soaks up Oxygen so that your weld isnt porous. Silicon also helps to weld metal to flow.
If you use an active gas you will burn out quite a bit of the Silicon and some of the Managanese resulting in a weld metal thats a bit softer and weaker. The black glassy slag on the weld surface is largely SiO2.
Some of the cheap MIG wires use low quality steel that is low on Si and Mn. The price is related to the alloy content. This makes the steel weaker, the resultant weld weaker and as it reduces the stiffness of the wire it also makes it more difficult to feed.