1. In order to prevent the erosion between the eyes due to heating, the welding current should not be too large. It is less than 20% less than the carbon steel electrode. The arc should not be too long. The interlayer cooling is fast. The narrow weld bead is suitable.
2. The hardening of stainless steel pipe fittings after welding is relatively large, which facilitates the occurrence of cracks. If it is welded with typical stainless steel pipe fittings, preheating above 300 ℃ and slow cooling treatment at 700 ℃ after welding must be performed. If the weldment cannot be processed after welding, stainless steel pipe electrode should be used.
3. Stainless steel pipe fittings, in order to improve corrosion resistance and weldability, add appropriate amount of invariable elements Ti, Nb, Mo, etc. 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 thermally treated, a chromium-nickel stainless steel electrode should be used.
4. The stainless steel pipe electrode has exquisite erosion resistance and oxidation resistance, and is widely used in the manufacture of chemicals, fertilizers, petroleum, and medical machinery.
5. Stainless steel pipe fittings have titanium calcium type and low hydrogen type. The titanium calcium type can be used for AC and DC, but the penetration depth is relatively shallow during AC welding, and it is also convenient for redness, so the DC power supply is generally adopted.
6. Stainless steel pipe fittings have certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. All materials used for power plant, chemical industry, petroleum and other equipment. The weldability of stainless steel pipe fittings is poor. You should pay attention to the welding process and choose suitable welding electrodes before heat treatment.
7. The electrode should be 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 (can not be dried again and again, otherwise the coating will be easy to crack and peel) The oily skin and other contaminants are used to prevent the weld from adding carbon and affecting the quality of the weldment.
8. When welding stainless steel pipe, it is heated repeatedly to precipitate carbides, which reduces the corrosion resistance and mechanical function.
