Stainless steel electrodes can be divided into chrome stainless steel electrodes and chrome-nickel stainless steel electrodes. Those two types of electrodes that meet the national standard shall be assessed in accordance with the national standard GB/T983-1995.
Chromium stainless steel electrode has certain corrosion resistance (oxidizing acid, organic acid, cavitation) heat and corrosion resistance. It is usually selected as equipment material for power stations, chemical industries, petroleum, and so on. However, the weldability of chromium stainless steel is generally poor, and attention should be paid to the welding process, heat treatment conditions, and the selection of suitable electrodes.
Characteristics and usage of a stainless steel electrode
1. Chromium stainless steel has certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. Usually used in power station, chemical, petroleum, and other equipment materials. The weldability of chromium stainless steel is poor, and attention should be paid to the welding process, heat treatment conditions and the selection of suitable electrodes.
2. Chromium 13 stainless steel has high hardenability after welding and is prone to cracks. If the same type of chrome stainless steel electrode (G202, G207) is used for welding, it must be preheated above 300 °C and slowly cooled at about 700 °C after welding. If the weldment cannot be subjected to post-weld heat treatment, chromium-nickel stainless steel electrodes (A107, A207) should be used. ??
3. Chromium 17 stainless steel, in order to improve corrosion resistance and weldability, appropriately increase the appropriate amount of stable elements Ti, Nb, Mo, etc., and the weldability is better than chromium 13 stainless steel. When using the same type of chrome stainless steel electrode (G302, G307), it should be preheated above 200°C and tempered at about 800°C after welding. If the weldment cannot be heat treated, chrome-nickel stainless steel electrodes (A107, A207) should be used.
4. The chromium-nickel stainless steel electrode has good corrosion resistance and oxidation resistance, and is 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. The chrome-nickel stainless steel coating has 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 become red, so DC power is used as much as possible. Diameters 4.0 and below can be used for all-position weldments, and 5.0 and above can be used for flat welding and flat fillet welding. ??
7. The electrode should be kept dry when used. The titanium calcium 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 repeat the drying many times, otherwise the coating will easily crack and peel off) to prevent the electrode. 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. In order to prevent eye-to-eye corrosion due to 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, and the layers are cooled quickly, and a narrow weld bead is appropriate.
