Aluminum welding standard

【China Aluminum Industry Network】Soldering method: A variety of welding methods can be used to weld aluminum and aluminum alloys. However, adaptability of aluminum and aluminum alloys to various welding methods is not the same. Various welding methods have their own application occasions. . Gas welding and electrode arc welding methods are simple and easy to operate. Gas welding can be used to repair welding thin aluminum plates and castings that do not require high welding quality. Welding electrode arc welding can be used for welding aluminum alloy castings. The Inert Gas Maintenance Welding (TIG or MIG) approach uses a wider range of aluminum and aluminum alloy welding methods. Aluminum and aluminum alloy sheets can be used for tungsten electrode argon arc welding or tungsten electrode pulse argon arc welding. Aluminium and aluminum alloy thick plates can be selected from tungsten arc welding, argon-helium mixed tungsten gas maintenance welding, gas metal gas welding, pulsed gas metal gas maintenance welding. MIG gas welding and pulse gas metal gas welding are more and more widely used (argon or argon/helium mixture).

1. Pre-weld finishing: When welding aluminum and aluminum alloys, the oxide film and oil stains of the workpiece weld and wire surface shall be severely removed before welding.

1) Chemical cleaning Chemical cleaning is of high efficiency and stable quality. It is suitable for finishing welding wire and small-scale, batch-produced workpieces. Available dip method and scrub method two. Can use acetone, gasoline, kerosene and other organic solvents to surface oil, alkaline cleaning with 5% to 10% NaOH solution at 40 °C ~ 70 °C for 3 min ~ 7 min (a little longer but not more than 20 min for pure aluminum), active water Erosion, followed by room temperature to 60 °C 30% HNO3 solution pickling 1 min ~ 3 min, activity water wash, air dry or low temperature dry.

2) Mechanical finishing: Mechanical finishing is often used when the workpiece has a large scale, a long production cycle, and multi-layer welding or chemical cleaning and then stains. First use acetone, gasoline and other organic solvents to wipe the surface to remove oil, then directly use a copper wire brush with a diameter of 0.15 mm to 0.2 mm or a stainless steel wire brush, and brush to expose the metal luster. Usually it is not suitable to use grinding wheel or sandpaper to sand, so as to avoid sand particles remaining on the surface of the metal, and welding slag inclusion and other disadvantages. Others can also use scrapers, trowels, etc. to sort out the surface to be welded.

After finishing, if the storage time is too long (eg, exceeds 24 h), it should be reprocessed.

2. Backing plate: The strength of aluminum alloy is very low at high temperature, and the mobility of liquid aluminum is good. In the welding process, the weld metal will simply collapse and appear. In order to ensure penetration without falling, welding is often used to support the molten pool and adjacent metal. Pads can use graphite plates, stainless steel plates, carbon steel plates, copper plates or copper bars. The outer surface of the backing plate is opened with an arc-shaped groove to ensure that the weld is not formed. It is also possible to perform double-sided molding without single-sided welding of the backing plate, but it is required to be skilled in the welding operation or to adopt advanced technical methods such as severe energy feedback control of arc welding.

3, preheating before welding: thin, small aluminum usually do not have to preheat, the thickness of 10 mm ~ 15 mm can be preheated before welding, according to different types of aluminum preheat temperature can be 100 °C ~ 200 °C, available Oxygen-acetylene flame, electric furnace or torch heating. Preheating can reduce the deformation of the weldment, reduce the porosity and other shortcomings. Post-weld treatment

(1) Post-weld welding The remaining welds and welding slag left behind in the weld joints and adjacent areas will damage the passive film on the aluminum surface, and sometimes it will corrode the aluminum parts and should be cleaned. The workpieces with simple shapes and the usual needs can be sorted out by simple methods such as hot water flushing or steam blowing. The aluminum parts with high demand and disorganized shape are brushed with a bristle brush after hot water top and then immersed in an aqueous solution of chromium anhydride or potassium dichromate at a concentration of 2% to 3% at 60°C to 80°C. Min ~ 10 min, and scrubbing with a bristle brush, then wash in hot water, dry with an oven, or dry with hot air, can also be naturally boring.

(2) Post-weld heat treatment Aluminum containers usually do not require heat treatment after welding.

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