[China Aluminum Industry Network] 1. Chemical Composition of Waste Distortion The chemical composition (main component and impurities) of the aluminum alloy exceeds the range specified in the national standard (GB/T3190--1996) or exceeds the internal (enterprise) standard (but in the national standard In the case of a product, the phenomenon that the product is inferior to the final product performance is called a chemical product waste product.
The main reasons for producing chemical waste are:
1) The chemical composition of the raw material does not meet the requirements, and the composition of the waste or master alloy or additive or metamorphic agent or reconstitution material or washing material is inaccurate;
2) waste mixture;
3) Ingredient error, including calculation errors, over-balance errors, stock preparation errors, inaccurate estimates of leftovers in the furnace, etc.;
4) The wrong charging material is used, the feeding material dilutes the error;
5) Incorrect sampling, rapid analysis error;
6) The method of adding magnesium is not correct, or the liquid metal stays in the furnace for too long, resulting in a lot of burning;
7) Stirring is not uniform;
8) The transfer team does not put dry, the washing furnace is not good;
9) When the electric furnace receives the liquid material of the flame furnace, the ladle for conveying the metal is not clean;
10) Others. Such as falling into the resistance wire, "run the child" and so on.
Second, the phenomenon that the temperature of the melt superheated alloy in the smelting and casting process is more or less than the allowable higher smelting temperature is called overheating.
The cause of overheating is:
1) The thermocouple is damaged and the instrument fails;
2) Failure to comply with smelting and casting procedures;
3) In the case of a high furnace temperature, the melt naturally warms due to the heat of oxidation of the metal or the heat of dissolution.
The fundamental measure to prevent overheating of the melt is to strengthen the responsibility of the post, observe the operating procedures, master the heating characteristics of the furnace and other thermal characteristics, and promptly repair the instrument. If the melt overheating occurs before the deterioration process, the melt can be cooled to the normal temperature range and continue to operate according to the regulations. If it occurs after the deteriorating treatment, 0.005% to 0.05% of titanium may be added within the scope of the national (Ministry) standard. For alloy products that do not allow the titanium or titanium content to reach the upper limit of the standard, if the use is not important, they can be cast according to the normal regulations after the melt temperature is lowered, and then inspected as usual, but special measures should be taken during casting to prevent Casting cracks. For important products, it should be changed to general products, try not to scrap.
Third, the excessive hydrogen content of hydrogen in aluminum hazards, mainly: In the casting performance, with aluminum and aluminum alloy in the hydrogen content increases, the ingot in the formation of loose, porosity, small white spots, small tails and other defects tend to increase. And make the casting and deformed aluminum alloy semi-product airtight. In terms of heat treatment performance, the presence of hydrogen in the supersaturated state and the combined state in the ingot is an important reason for the secondary porosity and surface blistering of the ingot to be homogenized and semi-finished. In the process of pressure processing, the delamination defects in the semifinished products are proportionally increased with the increase of hydrogen content. The flaking of the surface of the sheet and the bright scales in the forgings are directly caused by hydrogen (but this hydrogen is not Of the ingot from the ingot). Recently, it has been found that there is a second type of hydrogen embrittlement in aluminum and aluminum alloys. With the increase of hydrogen content, the brittle fracture temperature range is enlarged, and the transverse section shrinkage is significantly reduced, making the alloy more brittle during forging and rolling. Hydrogen in the alloy is also one of the causes of pitting corrosion during electrolytic polishing, and deteriorates the surface state after turning. In terms of mechanical properties, as the hydrogen content increases, the strength, ductility, impact toughness and fracture toughness of ingots and semi-finished products are significantly reduced.
Wooden Door,Mdf Door,Solid Wood Door
Steel Door,Toilet doors,Wood Door Co., Ltd. , http://www.steeldoors-manufacuturer.com