What are the precautions for heat treatment of aluminum sheet material? Today Mingtan aluminum veneer manufacturer's editor to take you to understand:
Aluminum material in the air is extremely unstable, easy to generate with the naked eye is also difficult to identify the oxide film. Due to the different processing methods of aluminum parts, such as casting, or by the extension of the plate directly cut into, or mechanical fine processing molding, or by different processes after molding and heat treatment or welding, etc., the surface of the workpiece will show different states, different degrees of dirt or traces, which must be pre-treatment process according to the actual situation of the surface of the workpiece to select the pre-treatment process method.
(1) fine machining parts in the pretreatment process need to pay attention to the problem: fine machining parts, although the surface of the natural oxide film is only the first generation, it is easier to remove, but the greasy heavy, especially within the eyelet and its surroundings (due to the lubrication needs of the machining process and added), this type of workpiece must be cleaned by organic solvents, if the direct use of alkali washing is not only greasy and heavy and difficult to get rid of the net, and fine machining surfaces can not withstand the long time of the corrosion of the strong alkali The result will also affect the roughness of the surface of the workpiece and the tolerance of the fit, and ultimately may become scrap.
(2) casting molding parts in the pretreatment process needs attention. Casting molded parts are not all surfaces are machined, not machined surfaces remain in the casting process of the formation of the thick oxide layer, some also sand layer, this time should be the first machining or sandblasting method to remove this part of the original oxide film, or by alkali washing and then processed, the only way to get rid of both the unprocessed parts of the original oxide layer, but also to avoid machining parts of the tolerance of the size of the change.
(3) after heat treatment or welding process of the workpiece in the pre-treatment process need to pay attention to the problem: according to the process requirements, the workpiece into the heat treatment or welding process before the need to be cleaned by organic solvents, in addition to the net surface oil contamination, but at present, generally do not do this, so the formation of a layer of the surface of the workpiece oil sintered coking material, this layer of coking material in organic solvents is difficult to get rid of the net, if immersed in alkali liquid will cause local corrosion, produce pitting or cause unevenness. This layer of coking material is difficult to remove in organic solvents, if immersed in alkali solution, it will cause local corrosion, pitting or unevenness, which will seriously affect product quality. With concentrated nitric acid immersion method to soften the layer of coked material, to be coked material after softening and then in the lye solution with a little cleaning that can be completely removed.
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