1. In order to prevent the corrosion between the eyes due to heating, the welding current should not be too large, 20% less than carbon steel electrode, the arc should not be too long, the interlayer cooling is fast, and the narrow welding bead is better.
2. The hardenability of stainless steel pipe fittings after welding is relatively large, which facilitates cracks. If welding with typical stainless steel pipe fittings is adopted, preheating above 300℃ and slow cooling at 700℃ after welding must be carried out. If the weldment cannot be subjected to post-weld heat treatment, stainless steel pipe fitting electrodes should be used.
3. For stainless steel pipe fittings, appropriate amount of invariant elements Ti, Nb, Mo, etc. are added to improve corrosion resistance and weldability. The weldability is better than stainless steel pipe fittings. When using the same typical chromium stainless steel electrode, it should be preheated above 200 ℃ and tempered at 800 ℃ after welding. If the weldment cannot be heat treated, chromium-nickel stainless steel electrode should be used.
4. Welding rods for stainless steel pipe fittings have exquisite corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.
5. The coating of stainless steel pipe fittings has titanium calcium type and low hydrogen type. Titanium-calcium type can be used for AC and DC, but the penetration depth is relatively shallow during AC welding, and it is convenient for redness, so DC power supply is generally used.
6. Stainless steel pipe fittings have certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. It is generally used as a material for equipment and furnishings such as power stations, chemicals, and petroleum. The weldability of stainless steel pipe fittings is poor, so you should pay attention to the welding process and choose suitable welding electrodes before heat treatment.
7. The electrode should be kept dry during operation. The calcium-titanium type should be dried at 150°C for 1 hour, and the low-hydrogen type should be dried at 200-250°C for 1 hour (do not dry repeatedly, otherwise the coating will easily crack and peel). The coating sticks to oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.
8. When stainless steel pipe fittings are welded, carbides are precipitated after repeated heating, which reduces corrosion resistance and mechanical performance.
