The composition of the flux determines the welding operation of the welding material and the mechanical property of the molten metal, and if the flux ingredient is mainly acidic, then the welding slag is produced, and the same basic (stone gray matter) flux will produce alkaline solder slag. The welding material of acidic system is very good, the welding process is smooth and stable, the shape resembles the jet arc, the splash quantity is few, the work is widely liked by the welding personnel, the molten metal mechanical ordinary but can reach the AWS specification request.

The solder material of the basic system can make the molten metal obtain very good ductility and toughness, but the operation is much worse than the acid system. The transition of droplet is mainly the transition of ball drop, splash is more.

The development of the flux system of low alloy steel welding material combines the operation of acidic system with the excellent mechanical property of alkaline system.