Argon is a rare gas widely used in industry. It is very inert in nature and can neither burn nor support combustion. In the sectors of aircraft manufacturing, shipbuilding, atomic energy industry and machinery industry, argon is often used as the welding protection gas when welding special metals, such as aluminum, magnesium, copper and their alloys and stainless steel, to prevent the welding parts from being oxidized or nitrided by air.