1. The use of vertical external characteristics of the power supply, DC with positive polarity (wire connected to the negative pole)
2. Generally suitable for the welding of thin plates of less than 6mm, with weld shaping beautiful, welding deformation of a small amount of the characteristics of the
3. Protective gas for argon, purity of 99.99%. When the welding current is 50"150A, argon flow rate of 8"10L/min, when the current is 150"250A, argon flow rate of 12"15L/min.
4. The tungsten electrode protrudes from the gas nozzle length to 4"5mm is good, in the corner welding and other poorly shaded places is 2"3mm, in the groove of the deep place is 5"6mm, the nozzle to the working The distance from the nozzle to the work is generally not more than 15mm.
5. In order to prevent the emergence of weld porosity, the welded parts, such as rust, oil, etc. must be cleaned up.
6. Welding arc length, welding ordinary steel, to 2 "4mm is good, and welding stainless steel, to 1 "3mm is good, too long is not good protection.
7. Butt bottoming, in order to prevent oxidation of the back of the bottom welding channel, the back also need to implement gas protection.
8. In order to make the argon gas well protected welding pool, and facilitate the welding operation, the tungsten electrode center line and the weld workpiece should generally maintain 80 "85 ° angle, filler wire and the surface of the workpiece angle should be as small as possible, generally about 10 °.
9. Windproof and ventilation. Windy places, be sure to take measures to block the net, and indoors should take appropriate measures to change the air.
Stainless steel MIG welding points and considerations
1. The use of flat characteristics of the welding power supply, DC with reverse polarity (wire connected to the positive pole)
2. Generally used pure argon (purity of 99.99%) or Ar 2% O2, the flow rate of 20 "25L/min is appropriate.
3. Arc length, stainless steel MIG welding, generally in the conditions of the jet transition to the welding, the voltage should be adjusted to the arc length in the degree of 4 "6mm.
4. wind. MIG welding is susceptible to the effects of wind, and sometimes do for the wind and produce porosity, so the wind speed of 0.5m/sec or more, should take measures to prevent wind.
Stainless steel flux-cored wire welding points and precautions
1. The use of flat characteristics of the welding power supply, DC welding with reverse polarity. The use of general CO2 welding machine can be welded, but the pressure of the wire feed wheel, please loosen a little.
2. The shielding gas is generally carbon dioxide gas, the gas flow rate of 20"25L/min is more appropriate.
3. The distance between the welding nozzle and the workpiece should be 15"25mm.
4. Dry length, the general welding current of 250A below about 15mm, 250A above about 20"25mm is more appropriate.
Manual welding:
1, chromium stainless steel has a certain degree of corrosion resistance (oxidizing acids, organic acids, cavitation), heat and wear resistance. Usually used in power stations, chemical, petroleum
and other equipment materials. Chromium stainless steel weldability is poor, should pay attention to the welding process, heat treatment conditions and the selection of suitable electrodes.
2, chromium 13 stainless steel hardening after welding, easy to produce cracks. If the same type of chromium stainless steel electrode (G202, G207) welding, must be more than 300 ℃ preheating and post-welding 700 ℃ or so slow cooling treatment. If the weldment can not be post-weld heat treatment, it should be used chromium-nickel stainless steel welding rod (A107, A207).
3, chromium 17 stainless steel, in order to improve corrosion resistance and weldability and appropriate increase in the amount of stability elements Ti, Nb, Mo, etc., weldability is better than chromium 13 stainless steel. With the same type of chromium stainless steel electrode (G302, G307), should be more than 200 ℃ preheating and post-weld tempering treatment of about 800 ℃. If the weldment can not be heat-treated, the chromium-nickel stainless steel electrodes (A107, A207) should be used.
4, chromium-nickel stainless steel electrodes have good corrosion resistance and oxidation resistance, widely used in chemical, fertilizer, petroleum, medical machinery manufacturing.
5, chromium-nickel stainless steel welding, subject to repeated heating precipitation carbide, reducing corrosion resistance and mechanical properties.
6, chromium-nickel stainless steel flux skin has titanium calcium type and low hydrogen type. Titanium-calcium type can be used for AC and DC, but the AC welding depth of fusion is shallow, while easy to red, so as far as possible to use DC power supply. Diameter 4.0 and below can be used for all-position welding, 5.0 and above for flat welding and flat angle welding.
7, the use of welding rod should be kept dry, titanium calcium type should be dried at 150 ℃ for 1 hour, low hydrogen type should be dried at 200-250 ℃ for 1 hour (can not be repeated drying, otherwise the flux skin is prone to cracking and peeling), to prevent the electrode flux skin sticking to the oil and other filth, so as not to lead to the weld to increase the carbon content and affect the quality of weldments.
8, in order to prevent corrosion due to heating and produce eye-to-eye corrosion, the welding current should not be too large, less than the carbon steel electrode 20% or so, the arc should not be too long, the interlayer fast cooling to narrow the welding channel is appropriate.