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Welding stainless steel is primarily used at joints; when two stainless steel pipes need to be joined together, welding is employed. When selecting welding materials, it is essential to choose ones that are compatible with the stainless steel material. The author does not recommend using carbon steel welding materials for welding stainless steel. The acceptance of welded stainless steel products mainly involves checking for the presence of black iron oxide at the welds and the methods used to remove it. During electric welding, high temperatures are generated; once the welding rod at the weld site melts, it fuses with the stainless steel surface. At the same time, the surface oxidizes to form black oxides such as iron(III) oxide and iron(IV) oxide, which are known as slag. This layer of iron oxide is extremely difficult to dissolve in acids. If the area is exposed to acid for too long, the areas that have not been welded may also suffer from excessive corrosion, which not only affects the proper deposition of the coating but also impacts the physical and chemical properties of the stainless steel product. ) Method 1: We can first use the most practical approach, which is to dilute laundry detergent with water, soak the welded area in it, and then rinse it with clean water. If the oxide layer on the solder joint cannot be removed, we can use diluted sulfuric acid for immersion; since sulfuric acid is highly corrosive, it is essential to control the immersion time carefully – it should not be too long – and then rinse with clean water. Method 2: Make a tool with a pointed tip; the tip should be smooth and flat, without any depressions or sharp edges, so that the oxide scale on the surface can be removed wherever it is present. Method 3: The plating removal method is used to eliminate the oxide layer on the weld points. The composition of this oxide layer was studied; we can first pre-treat the surface layer of the oxide layer by using alkaline nitrate melting to soften it, and then clean the weld points, thereby achieving a smooth and clean surface on those points.