A must-read for welders who are new to electric welding: How to distinguish between welding slag and molten iron during welding?
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During the welding process, the welder can see a layer of covering floating on the surface of the molten pool. Which is commonly known as welding slag. How to distinguish dross and molten iron during electric welding is very important for welders who are new to electric welding.
1. Formation of welding slag
Welding slag is the product of the melting of the welding electrode coating and the high-temperature metallurgical reaction of the weld. Welding slag is mainly composed of metal oxides or non-metal oxides and other mineral salts. Since its density is much smaller than that of liquid iron during welding, the welder can easily observe a layer of floating matter on the upper part of the molten pool during the welding process.
Judging from the color, it is darker than the liquid iron in the molten pool, and flows in the opposite direction to the welding direction and on both sides of the rear, cooling as the welding continues, becoming dross.
2. The role of welding slag
Welding slag mainly protects the weld bead during the welding process. By covering the liquid metal in the molten pool with slag, the liquid metal and the air are separated, preventing the intrusion of harmful gases such as oxygen, nitrogen, and hydrogen in the air, thereby protecting the weld bead.
Therefore, during the welding process, we must pay attention to the welding angle to ensure that the dross flows to the rear and rear sides, so as to observe the shape of the weld, avoid the occurrence of defects such as slag inclusions and pores, and ensure the welding quality.
3. According to the observation and identification by an experienced welder on site
If you look closely at identifying molten iron during welding, you will find that the welding slag floating on the liquid molten iron is similar to the oil splash in the water. It floats on the molten pool and is easy to identify.