Enterprise name：Foshan steel warrior metal products co., ltd.
Address：No.38, wanhua industrial zone, wanhua village Committee, shiwan town, Chancheng district, Foshan city
Usually stainless steel pipe 304 pressure pipe welding, stainless steel pipe argon shielded tungsten argon arc welding bottom welding is a commonly used method for stainless steel and some special steel pipe welding, because this method is time-consuming, labor-consuming, gas-consuming and some welding joints can not be protected by argon at all. That is to say, tungsten argon arc bottom welding is carried out with flux-coated wire or flux-cored wire; in the operation process, considering in-pipe slag protection, the general guiding idea is to intentionally flow the slag from the molten pool into the pipe, which plays the role of protecting the inner surface weld.
2. Pre-welding preparation
1. Clean up the oil, dirt, dirt, water and oxide near the joint of 1Cr18Ni9Ti 89 *6mm to make it glossy.
2. Selection of welding material: TGF 308L self-shielded stainless steel flux-free argon coating wire for bottom welding is 2.5mm; or ER 308L stainless steel flux-cored wire is 2.2mm. A132 stainless steel electrode for cover (filling) welding is 3.2mm.
3. Argon is generally used as shielding gas for frontal welding. The purity of shielding gas should be more than 99.95%, and the flow rate is generally 10L/min.
4. Making groove, 30-35 degrees on one side, group alignment, offset less than 1 mm; using flux-coated wire for spot-fixed position welding, horizontal fixed all-position welding, three locating welds are uniformly distributed, six locations are initial welds, to ensure the strength of locating weld, the length of locating weld is about 10 mm, and the height is about 1/2 of wall thickness after slag cleaning. The two ends of the positioning weld are ground into gentle slopes to facilitate the smoothness of the joint.
5. Welder: WS400, tungsten electrode 2.5mm, nozzle 14mm, welding wire TGF308L 2.5, current (bottom) 90-110A, flow rate 10L/min.
3. Bottom welding of stainless steel pipes
1. Arc ignition on the groove surface and immediately retreat to the initial groove solder joint (usually about 10 mm before the 6-point position). When the melting begins, the welding wire is filled immediately so that the welding wire and the base metal are fused together. At this time, it can be seen that the molten liquid and the molten slag flow uniformly through the groove to the pipe to form a molten hole; the welding torch oscillates in a small zigzag shape, slightly faster. Moving upward, the welding wire is always protected by argon gas, and should be pasted at the gap between the obtuse edges of the groove. The intermittent wire feeding method is adopted, one pull one feed, one drop one feed to the molten pool.
2. In the welding process, the short arc operation should be maintained; the handle should be stable, the wire feeding should be clean and neat, and the distance between the wire and the tungsten pole should be paid attention to, so as to prevent "tungsten beating", otherwise, the wire should be grinded clean before re-welding.
3. Controlling the size and shape of the melt hole is the key to double-sided forming of bottom welding.
4. In the process of bottom welding, the welding wire should be melted evenly, and a thin layer of slag should penetrate into the nozzle evenly, so as to protect the weld seam with slag, which is why flux-bonded wire is used.
5. Hammering after welding can make the welding slag fall off. Compressed air or water flushing can also be used to remove the welding slag in the pipe, so that a beautiful golden weld can be obtained in the pipe.
4. Cover welding
1. This weldment adopts bottom welding and cover welding.
2. A132 stainless steel electrode is used for cover welding. Its size is 3.2mm and current is 80-120A.
3. The welding position is all-position welding. Short arc welding should be adopted and the overlap amount should be more than 10 mm.
4. Slow cooling after welding.