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  Posted by: admin(管理员) Date: 2013-11-5 Hits: 1007
After welding of aluminum and aluminum alloys

Weld welding is finished, if you are using gas welding coated electrode welding, before the Visual inspection and non-destructive tests on welds, you need to either side of the weld and residual flux and slag removal, in order to prevent corrosion residual flux and slag weld and surface to avoid negative consequences.One, clear residuesWeld welding is finished, if you are using gas welding coated electrode welding, before the Visual inspection and non-destructive tests on welds, you need to either side of the weld and residual flux and slag removal, in order to prevent corrosion residual flux and slag weld and surface to avoid negative consequences.Common methods for post-weld clean up is as follows:(1) in 60 ¡æ ~~80 ¡æ hot water wash;(2) in the potassium dichromate (K2Cr2O2) or mass fraction of chromic anhydride for 2%~3% (Cr2O2);(3) in 60 ¡æ ~~80 ¡æ hot water washing;(4) into the oven drying or air drying.In order to test the effects of residual flux remover, drops of distilled water on the weld seam, and then distilled water is collected and drops into the cuvettes containing 5% nitric acid solution, such as a white precipitate, it means that the residual flux has not been cleared completely.

Second, the weld surface treatmentThrough the appropriate and correct technique of welding process, welding of aluminum and aluminum alloy weld surface, smooth ripples with uniform appearance.Anodized, especially when using polishing and staining techniques, high quality decorative surfaces are available.Decrease in weld heat-affected zone, anodized can be used to minimize adverse color changes.Use rapid welding process, minimizes weld heat-affected zone.Flash butt welding of welding, anodizing quality is good.  In particular won't heat treatment annealing condition hardened alloy Weldment, Anodic treatment, basic metal and weld heat-affected zone of the color contrast between the smallest.Furnace brazing is not a local heating and dipping, so the appearance of metal color is very even.Heat-hardened alloy, often used as structural parts, which after welding, anodizing.In these alloys, welding heat will form elements of precipitation, anodized after, differences arise between weld and heat affected zone.Halo of those close to the welding area, use rapid welding minimizes it, or use a cooling pad and cushion Halo reduction can also be made into very small, these Halo in welding, anodized front, solid falls can be eliminated.Chemical treatment of Weldments, sometimes encountered weld metal and base metal color varies, and this necessitates his fine selection of filler metal composition, especially when the alloy compositions containing silicone, it will have an impact on color matching.Welding can if necessary be mechanically polished.Commonly used mechanical polishing polishing, polishing, abrasive jet hit, shot peening, and so on.Mechanical polishing grinding, deburring, roll through the light, physical methods, such as polishing or sanding aluminum surface of the workpiece.Its purpose is through the process as little as possible to get the required surface quality.However, aluminium and aluminium alloy is a soft metal, and relatively high coefficient of friction, and if overheating occurs during the grinding process, it is possible to make a weld deformation, base to the grain boundary fracture phenomena.This requires adequate lubrication during the polishing process, pressure on the metal surfaces should be reduced to a minimum.Third, post weld heat treatment
Post weld heat treatment is designed to improve or eliminate the microstructure and properties of welded joint of residual stresses.
Enhancement of heat treatment after welding of aluminum alloy and may be heat-treated, base metal strength of the heat-affected zone of return close to its original strength.Under normal circumstances, joint damage is usually within the weld bond.After post weld heat treatment again, gained strength of weld metal, mainly depending on the filler metal.Filler metal is different from the base metal composition, will depend on the strength of filler metals on base metal dilution.Best adapted heat treatment used for strength and welded metal.

Due to precipitation and grain boundary of weld bond near melting, heat-strengthened aluminum alloys weld toughness is really bad, if the situation is not too serious, post weld heat treatment can dissolve soluble constituents back, get a more uniform structure, ductile, slightly improved, and will significantly increase the intensity.

Full back weld heat treatment is not practical, welding can weld the solution heat-treatment, carries on the artificial aging treatment after welding.In this welding method, when using high welding speed, and sometimes have access to significantly improve performance, exceeding the strength of the normal welding conditions.However, weld rarely reach full performance to heat again.

 D, weld plastic weld repairA product after the welding is completed, the contour defects in welds must be plastic surgery:(1) connector (high, wide mass variance is very beautiful);(2) fat tumor.Fat tumor is too much molten metal, mechanically stacked together with baseplate and no conflation is not part of the weld must be shoveled;(3) the overlap by the intermittent welding arc.Plastic shovel stick various shape tools are generally used, repaired and profile with a good seam pretty much the same, when the repairing does not allow parent material have scratches or cuts.According to national standards for weld defects that are not allowed, you must repair.Repair procedures are supposed to determine the scope of repair shall normally be extended 50~70mm both ends respectively to defects.According to testing results have been able to determine whether the defect is closer to the inside or outside of the product, you can repair it before and cannot determine which side are, they must be two-sided repair, usually take for repair outside the inside of the post.

Defects must be dug up before the repair, using pneumatic chipping and is fortified with flat shovels flattened the weld is high, and then excluded from the shovel ditching, ditching the depth of is to find defects, defects cleared, revealing well preserved until the metal.Handful if defect is large, out of the grooves are too wide and too deep, you must first repair welding, after fully patched, driving Groove, and then repair to welding.Repair welds must be confirmed by testing in accordance with the standard requirements, the best qualified rework.

 




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