Advantages, that can be derived by using metal-cored electrodes instead of solid-metal electrodes, are outline in the present paper. One of these advantages is that metal-cored electrodes provide improved penetration of the weld into the base metals and, therefore, help to minimize rework caused by missed joints, blow holes and lack of sidewall fusion, and minimizing rework saves money. As metal-cored electrodes offer more flexibility in alloy composition than is solid-metal electrodes manufactured by steel mills special chemistries can be formulated for the cores that address specific welding conditions. i.e. when welding high strength steels. The internal components of metal-cored electrodes begin with iron. Other powdered metals, metal alloys and chemicals, such as potassium and sodium, are added, and help to determine the properties of the formulation and the weld it produces. A metal core could be developed to stabilize or to enhance a welding arc or to reduce oxidation in the weld. These electrodes are also able to produce an improved bead appearance, less surface porosity and spatter when welding through mill scale, rust and other surface contaminants. However, solid metal electrodes that include deoxidizers also can be used to weld over light and medium mill scale. Some improvements have been attained when using metal-cored electrodes to weld thin sheets and galvanized sheets. These improvements include the combination of pulsed waveforms and metal-cored chemistries that can yield better travel speeds on thin materials and better bead wetting. Fabricators who are welding alloys that are sensitive to hydrogen in high restraint conditions must be careful in their specification of metal-cored electrodes because these electrodes can range from H4 to H8 in diffusible hydrogen. It is often necessary to replace drive rollers on wire feeders when using metal-cored electrodes because of changes in wire diameter.
Know your core abilities. Use metal-cored electrodes wisely.
Welding Design and Fabrication ; 79 , 8 ; 22-24
2006
3 Seiten, 3 Bilder
Article (Journal)
English
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