Stainless Steel Welding Need To Pay Attention To What Matters?

- Jun 29, 2018 -

Stainless steel welding points and notes

1. Adopt vertical external power supply, use positive polarity at DC (wire to negative)

2. It is generally suitable for the welding of thin sheets below 6mm, which has the characteristics of beautiful weld appearance and small welding deformation.

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

4. The length of the tungsten electrode protruding from the gas nozzle is preferably 4"5mm. It is 2"3mm where the shielding property such as fillet welding is poor and 5"6mm when the groove is deep. The distance from the nozzle to the working is generally not More than 15mm.

5. In order to prevent the occurrence of welding porosity, rust, oil, etc. must be removed from the welding area.

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6. Welding arc length, when welding ordinary steel, 2"4mm is preferable, and when welding stainless steel, 1"3mm is preferable, and if it is too long, the protection effect is not good.

7. When the bottom of the docking is in order to prevent the back of the bottom bead from being oxidized, the back side also needs gas protection.

8. In order to make argon well protect the welding pool and facilitate the welding operation, the tungsten pole center line and welding part should generally maintain an angle of 80 "85°. The angle between the filler wire and the workpiece surface should be as small as possible. It is generally around 10°.

9. Wind and ventilation. Where there is a wind, please take measures to block the net, and take appropriate ventilation measures indoors.

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Stainless steel MIG welding points and notes

1. Adopt flat-type welding power source, reverse polarity when welding at DC (wire to cathode)

2. Generally pure argon (99.99% purity) or Ar 2% O2 is used, flow rate is 20"25L/min.

3. The arc length, MIG welding of stainless steel, is generally applied under the conditions of injection transition. The voltage should be adjusted to an arc length of 4"6mm.

4. Wind protection. MIG welding is easily affected by the wind, and sometimes it is caused by the wind, resulting in blowholes. Therefore, measures should be taken to prevent wind at wind speeds above 0.5 m/sec.

Stainless steel flux cored wire welding points and notes

1. Use a flat-type welding power source, and use reverse polarity for DC welding. Welding can be performed using a general CO2 welder, but the pressure on the feed roller should be slightly loosened.

2. The protective gas is generally carbon dioxide gas, and the gas flow rate is preferably 20"25L/min.

3. The distance between the tip and the workpiece is preferably 15"25mm.

4. Drying elongation: The general welding current is about 15mm when the welding current is 250A or less, and about 20"25mm when the welding current is 250A or more.

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manual welding: 

 1, chromium stainless steel has a certain degree of corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. Usually used for power station, chemical, petroleum

And other equipment materials. Chromium stainless steel is poor in weldability, and attention should be paid to the welding process, heat treatment conditions, and the use of suitable electrodes.

 

  2, chromium 13 stainless steel hardened after welding, prone to cracks. If using the same type of chromium stainless steel electrode (G202, G207) welding, preheating above 300°C and slow cooling around 700°C after welding must be performed. If the weldment cannot be post-weld heat treatment, a chromium-nickel stainless steel electrode (A107, A207) should be used.

 

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

 

  4. Chrome-nickel stainless steel electrodes have good corrosion resistance and oxidation resistance and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

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  5, chromium-nickel stainless steel welding, subject to repeated heating precipitation of carbides, reducing corrosion resistance and mechanical properties.

 

  6, chromium-nickel stainless steel coating titanium calcium type and low hydrogen type. Titanium-calcium type can be used for AC and DC, but the depth of penetration is shallow during AC welding and it is easy to turn red. Therefore, DC power is used as much as possible. Diameters of 4.0 and below can be used for all-position weldments, and 5.0 and above for flat and flat fillet welds.

 

  7. When the electrode is used, it should be kept dry. The titanium-calcium type should be dried at 150°C for 1 hour. The low-hydrogen type should be dried at 200-250°C for 1 hour (can not be repeatedly dried, otherwise the coating will be easily cracked and peeled off), preventing the electrode. The skin of the skin is sticky 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 the occurrence of eye-catching corrosion due to heating, the welding current should not be too large, less than about 20% of carbon steel electrode, arc should not be too long, fast cooling between layers, with a narrow bead suitable


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