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Austenitic stainless steel has good weldability, and no special welding procedures are generally required. However, if the welding rod is not selected properly, some welding defects will occur. For example, using carbon steel electrodes to weld stainless steel can cause intergranular corrosion in the stainless steel. Stainless steel affected by intergranular corrosion loses its corrosion resistance and will fracture along the grain boundaries under stress, losing almost all of its strength; this is the most dangerous form of failure for austenitic stainless steel. Since carbon is the main element responsible for intergranular corrosion, low-carbon or ultra-low-carbon stainless steel electrodes should be used for welding stainless steel, such as electrodes like Ö102, Ö132, Ö002, etc. Can acidic electrodes be used for welding important structures that require high impact toughness and crack resistance? The flux of acidic welding electrodes contains a high amount of oxides, which are highly oxidizing; as a result, the weld metal has a high oxygen content, and alloying elements are also lost in large quantities. Moreover, there is a large amount of silicon dioxide in the flux; part of this silicon exists in the weld in the form of silica inclusions. As a result, the mechanical properties of the weld are poor, especially its plasticity and impact toughness, which are lower than those of alkaline electrodes. Furthermore, the flux in acidic welding electrodes does not contain fluorite (CaF2), resulting in low dehydrogenation capability ； The weld metal has a high hydrogen content, resulting in poor resistance to cold cracking ； Furthermore, the manganese content, an element that aids desulfurization, is low in the weld, resulting in poor desulfurization efficiency. Therefore, its resistance to thermal cracking is also poor. Therefore, for welding important structures, acidic electrodes should not be used; instead, alkaline electrodes with a low oxygen content in the weld metal, a high alloy transition coefficient, and low sulfur and hydrogen contents should be chosen. The mechanical properties and crack resistance of its weld metal are both better than those of acidic electrodes. Can alkaline electrodes be used for low-carbon steel weldments that cannot be cleaned due to certain constraints? Alkaline welding electrodes have poor weldability; they are sensitive to rust, oil, and moisture, and require thorough cleaning of the groove surface. If the workpiece is not cleaned properly, defects such as pores can easily occur during welding. Therefore, when the surface of low-carbon steel weldments, which cannot be cleaned due to certain constraints, is covered with contaminants such as scale and oil, alkaline electrodes should not be used. Instead, acidic electrodes with good weldability should be chosen; they have excellent resistance to porosity and are less sensitive to rust, oil, and moisture.