Eight Precautions for Stainless Steel Welding

1. Chromium stainless steel has certain corrosion resistance (oxidizing acids, organic acids, cavitation), heat resistance, and wear resistance. Usually used for equipment materials such as power plants, chemicals, and petroleum. Chromium stainless steel has poor weldability, and attention should be paid to welding processes, heat treatment conditions, etc.

2. Chromium 13 stainless steel has high post weld hardening and is prone to cracking. If the same type of chromium stainless steel welding rod (G202, G207) is used for welding, preheating at 300 ℃ or above and slow cooling treatment at around 700 ℃ after welding must be carried out. If the welded parts cannot undergo post weld heat treatment, chromium nickel stainless steel welding rods (A107, A207) should be used.

3. Chromium 17 stainless steel has better weldability than chromium 13 stainless steel by adding appropriate stabilizing elements such as Ti, Nb, Mo, etc. to improve its corrosion resistance and weldability. When using the same type of chromium stainless steel welding rods (G302, G307), preheating at 200 ℃ or above and tempering treatment at around 800 ℃ after welding should be carried out. If the welded parts cannot undergo heat treatment, chromium nickel stainless steel welding rods (A107, A207) should be used.

During the welding of chromium nickel stainless steel, repeated heating can precipitate carbides, reducing its corrosion resistance and mechanical properties.

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

6. Chromium nickel stainless steel coating has titanium calcium type and low hydrogen type. Titanium calcium type can be used for both AC and DC welding, but the melting depth is shallow during AC welding and it is prone to redness. Therefore, DC power supply should be used as much as possible. Diameter 4.0 and below can be used for all position welding, while diameter 5.0 and above can be used for flat welding and fillet welding.

7. Welding rods should be kept dry during use. Titanium calcium type should be dried at 150 ℃ for 1 hour, and low hydrogen type should be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating is prone to cracking and peeling), to prevent the coating of the welding rod from sticking oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the welded part.

To prevent inter-granular corrosion caused by heating, the welding current should not be too high, about 20% less than that of carbon steel welding rods. The arc should not be too long, and the inter-layer should be cooled quickly. Narrow weld beads are preferred.