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1.7 Storage and redrying

The coating of the rod electrode is hygroscopic, i.e. it absorbs water from the air during storage. Depending on the atmospheric humidity, the hydrogencontent in the casing may be too high. This leads to increased splashing and pore formation. It is therefore

necessary to store the electrodes in a closed packagein dry rooms. Basic-coated rod electrodes must be redryed to achieve their optimum quality (see label).

2.1 General information

Metal active-gas welding (MAG):l When using shielding gases, carbon dioxide or

mixtures (argon + carbon dioxide and/or oxygen)are used.

l The shielding gases used have free or still unbondedoxygen.

l Oxygen likes to form compounds and causes a chemical reaction during welding, and is therefore “active“.

l With shielding gases containing oxygen, plain , low-alloy and high-alloy steel is welded.

Metal inert-gas welding (MIG):l When using shielding gases, argon, helium or mix -

tures of these gases are generally used.l Shielding gases do not react with other substances

(inert = inactive).l Inert shielding gases are used to weld aluminium,

copper, titanium and other non-ferrous metals.

TSGTungsten gas-shielded arc welding

Non-melting tungsten electrode

TIG

Inert-Gas(low-activity gas/neutral gas)

Argon/Helium

Application:all weldable metals

For TSG welding, no active gas can be used.

MIG

Inert-Gas

Argon/Helium

Application:all oxygen-sensitive

materials, e.g. aluminium, copper

and their alloys

MAG

Active-Gas(reacting gas)

CO2/Mixed Gas

Application:all plain, low-alloy and

high-alloy steels and caststeels

MSGMetal gas-shielded arc welding

Meltingwire electrode

SG welding(Gas-shielded arc welding)

2. Gas-Shielded Arc Welding