Precautions for welding stainless steel pipe fittings

Precautions for welding stainless steel pipe fittings 1. To prevent corrosion due to heating, the welding time should not be too long, which is about 20% less than that of carbon steel electrodes. The arc should not be too long, the interlayer should be cooled quickly, and narrow welds are preferred. 2. Stainless steel pipe fittings harden quickly after welding, which is easy to crack. If welding with typical stainless steel pipe fittings, preheating above 300℃ and slow cooling treatment of about 700℃ after welding are required. If the weldment cannot be heat treated after welding, stainless steel pipe fittings should be used. 3. Stainless steel pipe fittings, to improve corrosion resistance and weldability, appropriate amounts of stable elements Ti, Nb, Mo, etc. are appropriately added, and the weldability is better than that of stainless steel pipe fittings. When using the same typical chromium stainless steel electrodes, preheating above 200℃ and tempering treatment of about 800℃ after welding should be carried out. If the weldment cannot be heat treated, chromium-nickel stainless steel electrodes should be used. 4. Stainless steel pipe fittings have excellent corrosion resistance and oxidation resistance and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing. 5. Stainless steel pipe fittings have titanium calcium type and low hydrogen type coating. Titanium calcium type can be used for AC and DC, but the penetration depth is shallow during AC welding, and it turns red at the same time, so it is best to connect to a DC power supply. 6. Stainless steel pipe fittings have certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance, and wear resistance. Generally used as equipment materials for power stations, chemical, petroleum, etc. Stainless steel pipe fittings have poor weldability, and attention should be paid to the welding process and selection of suitable welding rods before heat treatment. 7. The welding rod should be kept dry during operation. The titanium calcium type should be dried at 150℃ for 1 hour, and the low hydrogen type should be dried at 200-250℃ for 1 hour (it cannot be dried repeatedly, otherwise the coating will easily crack and peel off). Be careful of sticking oil and other dirt on the welding rod coating to avoid increasing the carbon content of the weld and affecting the quality of the weld. 8. When stainless steel pipes are welded, they are heated repeatedly to precipitate carbides, which reduces their corrosion resistance and mechanical properties. Post time: Sep-11-2024