Welding materials for welding stainless steel:

Rust steel electrode can be divided into chromium stainless steel electrode and chromium nickel stainless steel electrode, these two kinds of electrode in accordance with the national standard, according to the national standard GB/T 983-2012 provisions of the assessment. Chromium stainless steel has a certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat and corrosion resistance. It is usually used as equipment material for power station, chemical industry, petroleum and so on. But chrome stainless steel is generally weldability is poor, should pay attention to the welding process, heat treatment conditions and the selection of appropriate electrode. Chromium nickel stainless steel electrode has good corrosion resistance and oxidation resistance, widely used in chemical industry, fertilizer, petroleum, medical machinery manufacturing. In order to prevent intergranular corrosion due to heating, the welding current should not be too large, less than carbon steel electrode about 20%, the arc should not be too long, rapid cooling between layers, narrow weld pass is appropriate.

Stainless steel welding points and matters needing attention

A, the use of vertical external characteristics of the power supply, dc using positive polarity (welding wire with negative electrode)

1. Generally suitable for the welding of thin plates below 6mm, with the characteristics of beautiful weld forming and small welding deformation.

2. The protective gas is argon with a purity of 99.99%. When the welding current is 50-150A, the flow rate of argon is 8-10L /min, and when the current is 150-250A, the flow rate of argon is 12-15L /min.

3, the length of the tungsten pole protruding from the gas nozzle, with 4~5mm is the best, in fillet welding and other places with poor shielding is 2~3mm, in the deep slot is 5~6mm, the distance from the nozzle to the work is generally not more than 15mm.

4, in order to prevent the appearance of welding pores, welding parts such as rust, oil, etc. must be cleaned.

5, welding arc length, welding ordinary steel, 2~4mm is the best, and welding stainless steel, 1~3mm is the best, too long protection effect is not good.

6. When butt making, in order to prevent the back of the bottom bead from being oxidized, the back also needs to implement gas protection.

7. In order to make the argon gas well protect the welding pool and facilitate the welding operation, the tungsten center line and the welding workpiece should generally keep the Angle of 80~85°, and the Angle between the filler wire and the workpiece surface should be as small as possible, generally about 10°.

8, wind and ventilation. In windy places, please take measures to screen, and in the indoor should take appropriate ventilation measures.

Two, stainless steel flux cored wire welding points and matters needing attention

1, using flat welding power source, DC welding using reverse polarity. The common CO2 welder can be used for welding, but the pressure of the wire feeding wheel should be slightly relaxed.

2. The protection gas is generally carbon dioxide gas, and the gas flow rate is 20-25L /min.

3, the distance between the welding nozzle and the workpiece is 15~25mm.

4. Dry extension length, the general welding current is about 15mm below 250A, and about 20~25mm above 250A is more appropriate.