Precautions for using stainless steel welding rods

1. Chromium stainless steel has certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. It is usually used for equipment materials such as power stations, chemicals, and petroleum. The weldability of chromium stainless steel is poor, and attention should be paid to welding process, heat treatment conditions and selection of suitable welding rods.

2. Chromium 13 stainless steel has greater hardening after welding and is prone to cracking. If the same type of chromium stainless steel welding rod is used for welding, it must be preheated at more than 300°C and slowly cooled at about 700°C after welding. If the weldment cannot be heat treated after welding, chromium-nickel stainless steel welding rods should be used.

3. Chromium 17 stainless steel, in order 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 chromium 13 stainless steel. When using the same type of chromium stainless steel welding rod, it should be preheated at more than 200°C and tempered at about 800°C after welding. If the weldment cannot be heat treated, chromium-nickel stainless steel welding rods should be used.

4. Chrome-nickel stainless steel welding rods have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

5. When chrome-nickel stainless steel is welded, carbides are precipitated by repeated heating, which reduces corrosion resistance and mechanical properties.

6. Chrome-nickel stainless steel coatings are titanium calcium type and low hydrogen type. Titanium calcium type can be used for AC and DC, but the penetration depth is shallow during AC welding, and it is easy to turn red, so DC power supply should be used as much as possible. Diameters of 4.0 and below can be used for all-position welds, and 5.0 and above can be used for flat welding and flat corner welding.

7. The welding rod should be kept dry when used. 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). Prevent the welding rod coating from sticking oil and other dirt to avoid increasing the carbon content of the weld and affecting the quality of the weld.

8. To prevent intergranular corrosion caused by heating, the welding current should not be too large, about 20% less than that of carbon steel electrodes, the arc should not be too long, the interlayer should be cooled quickly, and a narrow weld is preferred.

9. Welding electrodes should be carefully selected for welding dissimilar steels to prevent improper selection of welding electrodes from causing thermal cracks or σ phase precipitation after high-temperature heat treatment, which will make the metal embrittled. Refer to the selection standards for welding electrodes for stainless steel and dissimilar steels, and adopt appropriate welding processes.