[Technology] Al-alloy compounding process

According to the process performance of the alloy itself and the technical conditions of the alloy processed product,
Within the scope of the chemical composition specified in the national standard or related standards, determine the alloying standards (Fr calculated into 3)-) charge composition and proportioning, and calculate the total charge of each furnace, and conduct charge and preparation of the charge. The process is called ingredients.

First, the basic tasks of ingredients The basic tasks of ingredients:
1 Control alloy composition and impurity content to meet relevant standards;
2 rational use of various charge materials, reduce production costs;
3 Guarantee the quality of the charge, and correctly prepare the material to create favorable conditions for improving the quality and yield of the fused cast product.

Second, the basic procedure of ingredients The basic procedure of ingredients:
1 clarify the task of ingredients, such as alloy grade, casting status, casting use and the approximate quality of the required alloy liquid;
2 determine the calculated composition of each element in the alloy;
3 Determine the composition of the charge and the charge ratio and melting rate of each charge, and determine the specific chemical composition of each charge;
4 Calculate the charge quality of each melt batch and the required amount of each charge;
5 Go to the material storeroom to take charge and prepare for smelting.

Third, determine the charge composition and the principle of charge ratio The charge composition refers to the composition of the charge of the various varieties and the quality of each species, and the ratio of ingredients refers to a charge in each charge furnace charge.
1. Aluminium alloy charge The charge of aluminum alloy consists of new metal, intermediate alloy, return charge and remelted return charge.
1 new metal. The new metal is a new metal that can be found in the national standard in terms of grade, grade, purity, and use. It is the main component of the charge and has a high purity and can be used to dilute the content of impurities introduced into the charge.
2 master alloys. To facilitate the addition of certain refractory alloying elements such as Cu, Mn,
Si, etc., or strictly controlled elements, such as rare earth elements such as Sb, need to be made into an intermediate alloy with pure aluminum in advance. The requirements for the master alloy are: the melting point is close to the temperature of the molten aluminum, the proportion of alloying elements is as high as possible, the chemical composition is uniform, the quality of the metallurgy is good, and it is easy to crush and the ingredients are weighed. The method of melting the intermediate alloy includes a direct melting method and an aluminum thermal method. The latter uses the oxide of the alloy element as a raw material, the cost can be reduced, but the melting temperature is high, the inclusions are numerous, and the working conditions are poor.
3 return charge. The recycled materials are divided into three categories: The first category includes components that are qualified for scrapped castings, pouring risers, etc., and can be used directly; the second category includes small flashes, residual metals in the sprue cups, trimming materials for stamping workshops, etc., which need to be remelted. Reclaimed alloy ingots can only be used;
The third category includes slag, swarf, bottom residue and scrap metal with unqualified chemical composition. If the iron content is too high, it must be remelted into a regenerative alloy ingot by a specialized metallurgical plant.
The return material is hereditary and has two types of "purity inheritance" and "tissue inheritance".
The high-purity, fine-grained charge has a high genetic mass, and the quality of the melted alloy is also high, sometimes being of better quality than the lower grade new metal melted alloy.
The potential crystalline nucleus in the aluminum liquid, that is, the presence of radicals arranged in close proximity, is the cause of tissue genetics. After a long period of incubation at a constant temperature, tissue heredity can still be preserved even after ultrasonic treatment, indicating that these radicals are quite stable.
If the liquid aluminum is overheated to 200-300,000 or more above the liquidus, the atomic mass disappears, and then it is mixed with another low-temperature aluminum liquid phase, and the rapid casting can refine the alloy structure and improve the mechanical properties. This kind of process is called "temperature processing" or "rapid heat treatment" and it is worth studying in depth.
2. The principle of determining the composition of the charge and the ratio of the ingredients When determining the composition of the charge and the ratio of the ingredients, the following five principles should be followed.
1 ingredient principle. That is, the used charge should be able to ensure that the alloy composition after smelting is qualified. The content of harmful impurities should be within the allowable range. According to this principle, the higher the impurity requirements of the alloy, the higher the quality of the new metal material used, the greater the proportion.
2 quality principles. That is, the charge composition and ingredient ratio must be determined to ensure the product's quality requirements. According to this principle, for military products or important-use alloy products,
New metal materials with high quality and relatively large quantities should be selected. For casting products with low quality requirements, materials of lesser quality may be used.
3 process principles. That is, in determining the charge composition and ratio, the smelting process characteristics and equipment performance of the alloy should be taken into consideration to ensure the smelting quality. According to this principle, for a narrow range of alloying elements in the alloy, the intermediate alloy should be used as the charge material instead of pure metal to ensure uniform chemical composition. When using resistance furnace smelting, for each secondary material with a large specific surface area and poor density, the amount of each furnace is preferably not more than 20% -
30% and avoid secondary feeding.
4 Economic principles. That is, under the premise of guaranteeing the composition and performance of the castings, new low-quality metals and multiple-use wastes should be adopted as much as possible. According to this principle, for those alloy castings with no special requirements, it is permissible to replace the original aluminum ingots with new ones with the same series of low-component alloy first-stage scraps or washing materials, and when the charge is all one or two scraps, it is possible not to use them. New aluminum, when lacking the required quality of the original aluminum ingots, allows the use of high and low masses.
5 material balance principle. That is, new and old materials should be compatible with the metal balance of the whole plant, avoiding the use of new materials at one stage, and using old materials at a time to ensure the stable quality of castings, stable technology, and stable cost.
Fourth, the ingredients calculation examples The ingredients calculation procedure is as follows:
1 clearly assigned batching tasks, such as alloy grades, smelting quality of each casting, etc.;
2 Determine the calculated composition according to the internal specifications of the chemical composition or relevant standards, and determine the charge composition and proportioning ratio according to the ingredients specification, past experience and material inventory;
(3) Determine the chemical composition of each charge and calculate the required amount of each element;
4 Calculate the amount of charge, intermediate alloy and new metal at all levels;
5 Proofread and fill in the casted card, weigh and receive the raw material.
[Example] To prepare an LC4 alloy for a furnace bar, the total mass is 100kg. How do you calculate the ingredients?
1 Determine the calculated composition based on the chemical composition and internal specifications of the LC4 alloy bar, see Table 6-1.

3 Calculate the required amount of each element based on the total amount of ingredients.
Calculation method: total amount of ingredients x mass fraction.
The result of the calculation is as follows:
Element symbol Cu Mg Mn Zn Cr Fe Si Ti
Required amount 峪1.55 2.20 0.30 6.10 0.15 <0.45 <0.30 0.04
4 Calculate the amount of elements brought back by the various return materials.
Calculation method: proportion of the total amount of ingredients X ratio of the ingredients in the X return charge.
The results are shown in the table below.
5 Calculate the requirements for each intermediate alloy and pure metal.
Calculation method:
The amount of pure metal = the amount of element required. The amount of element introduced into the charge once. The amount of the intermediate alloy = (The amount of element required to be fed back into the charge) The percentage of the element in the master alloy The amount of primary aluminum ingot = New The total metal amount of a pure metal amount and an intermediate alloy amount are calculated as follows:
Electrolytic copper plate: 1.55 to 1.07 = 0.48 (kg)
Magnesium Ingot: 2.20 to 1.53=0.67 (kg)
Zinc ingots: 6.10 to 4.15 2.95 (kg)
Al-Mn master alloy: (0.30 - 0.229) - 10.5% = 0.68 (kg)
Al-Cr master alloy: (0.15 -0.0975) -4% = 1.31 (kg)
Al-Ti master alloy: (0.04-0.035) = 3.5% = 0.14 (kg)
Al It: 25 One ((0.48+0.67+1.95) One ((0.68+1.31+0.14)=19.77 (kg)
6 Check whether the impurity content is within the required range.
Calculation method: Add the impurity content of each charge and then compare it with the calculated amount required for the composition.
The result of the calculation is as follows:
Fe: 0.31+0.68 x 0.5%+1.31 x 0.6%+0.14 x 0.5%+19.77 x 0.25%
=0.3714<0.45 (kg)
Si: 0.154+0.68 x 0.3%+1.31 x 0.3%+0.14 x 0.4%+19.77 x 0.18%
= 0.196<0.30 (kg)
The batch results meet the requirements and the above results are filled into the fused card.
After all the charge is weighed, it should be reviewed and checked and shipped to the smelting site.