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Stainless Steel Electrode Use Precautions

Mar 07, 2019

1. Chrome stainless steel has certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. Usually used in power plant, chemical, petroleum and other equipment materials. The chrome stainless steel has poor weldability, and attention should be paid to the welding process, heat treatment conditions and selection of suitable welding electrodes.

2. Chromium 13 stainless steel has high hardenability after welding and is prone to cracks. If welding of the same type of chrome stainless steel electrode (G202, G207) is used, preheating at 300 °C or higher and slow cooling at around 700 °C after welding must be performed. If the weldment cannot be post-weld heat treated, a chrome-nickel stainless steel electrode (A107, A207) should be used.

3, chrome 17 stainless steel, in order to improve corrosion resistance and weldability, appropriately increase the amount of stability elements Ti, Nb, Mo, etc., weldability is better than chromium 13 stainless steel. When the same type of chrome stainless steel electrode (G302, G307) is used, preheating at 200 °C or higher and tempering at around 800 °C after welding should be performed. If the weldment cannot be heat treated, chrome-nickel stainless steel electrodes (A107, A207) should be used.

4, chrome-nickel stainless steel welding rod has good corrosion resistance and oxidation resistance, widely used in chemical, fertilizer, petroleum, medical machinery manufacturing.

5. When chrome-nickel stainless steel is welded, it is repeatedly heated to precipitate carbides, which reduces corrosion resistance and mechanical properties.

6. The chrome-nickel stainless steel coating has a titanium calcium type and a low hydrogen type. Titanium-calcium type can be used for AC and DC, but the AC welding is shallower and easier to redden, so DC power is used as much as possible. 4.0 and below diameters can be used for all-position weldments, 5.0 and above for flat and fillet welds.

7. The electrode should be kept dry when it is 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 repeatedly, otherwise the coating will be easily cracked and peeled off) to prevent the electrode. The viscous oil and other dirt are not allowed to cause the weld to increase the carbon content and affect the quality of the weldment.

8. In order to prevent the corrosion between the eyes due to heating, the welding current should not be too large, about 20% less than the carbon steel electrode, the arc should not be too long, the layer is fast cold, and the narrow bead is suitable.

9. Welding of dissimilar steels should be carefully selected to prevent the welding rod from being improperly exposed to hot cracks or high temperature heat treatment to cause σ phase precipitation and embrittlement of the metal. Refer to the selection criteria for stainless steel and dissimilar steel welding rods and adopt appropriate welding procedures.