Last edited 29 Dec 2020

How to Weld Pure Copper Steel Pipe And Steel Plate?

Pure copper China steel pipe is a very common pipe material, because pure copper pipe is mainly made of copper pipe. So it is different from stainless steel pipe in welding. Then, how to weld pure copper steel pipe and steel plate? Let's have a look!

(1) Weldability analysis of materials
Austenitic stainless steel has certain quenching tendency and special physical properties. It is easy to produce residual stress after welding, which leads to the occurrence of hot cracks. At the same time, harmful impurities precipitate into liquid and the crack tendency increases. When austenitic stainless steel works at high or low temperature, the welded joint is easy to embrittlement.

Do you know the welding between pure copper steel pipe and steel plate?

The physical properties of pure copper determine the poor weldability. The base metal and filler metal can not be welded well after welding. It is easy to produce non melting phenomenon and has large deformation after cooling. It is easy to produce large welding stress, and the influence of impurities in pure copper may lead to hot cracks. In argon arc welding of pure copper, if a small amount of hydrogen and water vapor are added in the welding, the formation of pores should be avoided.

There are great differences in physical properties between austenitic stainless steel and pure copper. Due to the effect of welding chemical composition, welding is easy to produce defects such as hot cracks, air holes, non deposition of joints and so on. Only the correct operation method can guarantee the quality.

(2) Selection of welding parameters
Welding wire
Both liquid and solid nickel and copper are infinite fusion, so pure nickel is used as filler material in welding. Therefore, pure nickel wire with a diameter of 2mm is selected.

Nozzle diameter and gas flow
The requirement of molten electrode arc welding on the protection of molten pool is very high. If the protection is not good, there will be wrinkles on the welding surface. So, the nozzle diameter is 20 mm. The argon flow rate was 35 ~ 40L / min.

Power polarity
In order to ensure the stability of the arc, choose a good DC melting electrode welding machine. On the contrary, the welding current is 90 ~ 210A.

(3) Preparation before welding
The distance from the overhanging end of pure copper pipe to stainless steel plate is 1mm, which is used for welding. Clean the surface of the workpiece oil, moisture and other foreign matters. When the stainless steel is scrubbed with acetone, the oil, water and other foreign matters shall be removed. Place the welded joint in the flat position.

(4) Operating point
Use the arc starter plate to pull the arc and slowly transfer to welding until the arc is stable.
The tilt angle of welding torch is 70 ~ 85, and the distance from nozzle to workpiece is 5 ~ 8mm.
The action mode of the torch is that the arc moves to the pure copper pipe. The pure copper tube moves to stainless steel after melting, and the arc center keeps slightly away from the pure copper tube.

During welding, the relationship between welding speed and welding should be paid close attention to according to the variation of current. Adjust the annular moving speed of welding torch in time to ensure that the molten pool is fully protected. Please bury the crater when you close the arc. After the welding of one piece is completed, the welding stress shall be removed from the area near the welding with a wooden hammer. After welding, remove the white powder residue on the surface and clean the welding surface with copper wire brush.

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