Stainless Steel Tube Welding Without Argon Welding

Usually stainless steel pressure tube welding, stainless steel tubings filled with argon-protected tungsten argon arc welding bottom welding is a common method used for welding stainless steel and some special steel tubes, because this method is time-consuming, labor-intensive, gas-intensive and some welding ports can not be charged at all. Argon protection; try to use the slag protection method, that is, using a welding wire or a flux-cored wire with a coating for tungsten argon arc welding; in the operation process, considering the protection of the slag inside the tube, the general guiding ideology is It is intended to flow the scum on the molten pool into the tube to protect the inner surface weld.

Preparation before welding

1. Clean the oil, dirt, scale, water and oxides near the interface of the weldment (1Cr18Ni9Ti 89×6mm) to make it shine.
2. welding consumables: TGF 308L for self-protecting stainless steel argon-free welding wire 2.5mm; or ER 308L stainless steel flux cored wire 2.2mm. Cover surface (filled) welding with A132 stainless steel electrode 3.2mm.
3. The front welding protection gas is generally argon gas, the purity should be greater than 99.95%, and the flow rate is generally 10L/min.
4. making the groove, single side 30 ° ~ 35 °, group positioning, the wrong side is less than 1mm; using the welding wire for point fixed welding, horizontal fixed all position welding, three positioning welding points are evenly distributed, 6 points The position is the starting solder joint. To ensure the strength of the positioning solder joint, the length of the positioning weld is about 10mm, and the height is about 1/2 of the wall thickness. After the slag is removed, the two ends of the welded seam are ground into a gentle slope to facilitate the joint flatness.
5. welding machine: WS400, tungsten 2.5mm, nozzle 14mm, welding wire TGF308L 2.5, current (priming) 90 ~ 110A, flow 10L / min.

Bottom welding

1. Guide the arc on the groove surface and immediately retreat to the starting point of the slope root (usually about 10mm before the 6 o’clock position). When it starts to melt, immediately fill the welding wire to fuse the welding wire with the base metal. It is seen that the molten metal and the molten slag flow uniformly into the tube through the groove to form a molten hole; the welding gun swings in a small zigzag shape, moves upward slightly, the welding wire does not leave the argon gas protection, and is attached to the blunt edge of the groove. , using the intermittent wire feeding method, one pull and one send, one drop and one drop to fill the molten pool.
2. in the welding process, to maintain short-arc operation; the handle should be stable, the wire should be clean, pay attention to the distance between the wire and the tungsten, to prevent “tungsten”, otherwise it should be polished and then re-welded.
3. Controlling the size and shape of the melt holes is the key to double-sided forming of the bottom weld.
4. During the bottom welding process, the welding wire should be uniformly melted, and a thin layer of slag is uniformly penetrated into the nozzle to protect the weld seam. This is the reason why the medicated welding wire is used.
5. after welding, hammering, so that the welding slag fall off; can also be used to remove the welding slag in the tube by compressed air or water, so that the tube gets a beautiful golden yellow weld.

Cover welding

1. The weldment is made of two layers of bottom welding and cover welding.
2. the welding material of the cover welding is A132 stainless steel electrode, the size is 3.2mm, the current is 80~120A.
3. the welding position is all-position welding, short arc welding should be adopted, and the overlap should be greater than 10mm.
4. slow cooling after welding.

Test

Posted by stainless steel tubing supplier and stainless steel pipe supplier KAYSUNS.