The magnesium melt does not react with iron as does the aluminum melt, so the iron crucible can be used to melt the magnesium alloy and contain the melt. The crucible used must be made of welded steel or cast steel and is mainly made of castable or bendable low carbon steel or nickel-free low alloy steel. Do not use graphite crucibles because it will absorb solvents and become brittle. Cast iron crucibles are also not to be used. They are prone to many flaws, such as blow holes, and they have a short service life due to their low resistance to high temperature creep. Low-carbon steel crucibles are commonly used to smelt magnesium alloys and cast parts, especially when large magnesium alloy castings are used.å©åŸš To prevent melting, heat-resistant materials are used on the outer surface. To prevent the formation of metal scale blocks, heat-resistant stainless steel can be used as the outer layer. In addition to extending the service life of the crucible, it is also possible to prevent the accumulation of the metal scale block on the bottom of the furnace. The crucible capacity for melting magnesium is generally in the range of 35-350 kg. Small crucibles are usually made of low carbon steel welds containing 0.12% of C below the mass fraction. Ni and Cu severely affect the corrosion resistance of magnesium alloys. Therefore, the contents of these two elements in steel crucibles should be controlled at a mass fraction of 0.10% or less. In the smelting process of magnesium alloys, especially in the flux smelting process, the lower thermal conductivity residue is usually formed at the bottom of the crucible. Residues settle at the bottom of the crucible and build up to form oxides, including magnesia, which increases the potential for contamination of the molten metal. The tongue 1 must be regularly removed, and the oxides are prevented from decreasing in the melting speed, and especially when die casting is performed intermittently, the aluminum, magnesium, manganese, and magnesium-containing compounds stacked on the bottom of the crucible are easily cured. What's more, even if it is heated, these metal compounds will not melt. The repetition of semi-finished die-casting makes the metal compound thicker, which significantly reduces the thermal conductivity. The reaction of the metal compound with Fe also causes the quality of the alloy to decrease. If these residues are not regularly removed, this will cause localized overheating of the crucible, and excessive oxide scale will be generated on the surface of the site j. The excessive deposition of oxides on the crucible wall can also lead to local overheating of the crucible. Therefore, the number of times each crucible melts the charge should be recorded as a daily safety measure. Must be soaked in water regularly to remove all fouling. Usually the fluxless smelting process has less fouling. Regular inspections should be carried out, usually once every quarter. Standards for abandonment of cockroaches should be established. The general practice is to abandon use when the wall thickness is reduced to less than half of the original thickness. Visual inspection should include observations of cracks on the interior and exterior surfaces of Site A. All metal scales should be removed prior to inspection. Each site A shall have a usage record card to record the specific contents of its service life, wall thickness and maintenance records. You can use nitrogen arc welding to repair the flaws: first weld the deepest layer, then polish, and then weld one layer, smooth it, and repeat until the corrosion hole is completely flattened. The name of the welding wire is EMK6 3. Magnesium alloy smelting and mixing device magnesium The chemical properties of the alloy are relatively lively. When it starts to melt, it is easily oxidized and burned. Protective measures are needed to prevent oxidation of the molten metal surface. The magnesium alloy melt is different from the aluminum alloy. A continuous and dense oxide film is formed on the surface of the aluminum alloy melt to prevent further oxidation of the melt. A loose oxide film is formed on the surface of the magnesium alloy melt, and the oxygen can penetrate the surface oxide film. This causes the metal below the oxide film to oxidize and even burn. In addition, melted magnesium alloys can easily react violently with water to generate hydrogen gas and may cause explosions. Therefore, it is necessary to use flux or protective atmosphere to isolate oxygen or water vapor from the magnesium alloy melt. In actual production, SF6 is often mixed with other gases and passed into the smelting furnace as a protective atmosphere. The commonly used mixing method is air/SF6' SF6/N2, air/C02/SF6 gas mixing device's function is to precisely Mix in a certain proportion and send it to the furnace. Experiments show that 0.01% SF6 concentration can effectively protect the magnesium solution, but the actual concentration is large. This is mainly because SF6 reacts with the magnesium solution and leakage loss. With the increase of the input concentration, the SF6 concentration above the liquid surface It also increased, but the consumption increased as compared with the input concentration. Therefore, the magnesium alloy furnace device must be effectively sealed, so that it becomes possible to control SF6 to a certain concentration. Generally, the concentration of SF6 should not exceed 1%. At this time, not only does the antioxidant effect decrease, but also the atmosphere has serious corrosion effects on the equipment. Therefore, the optimization of the protection gas supply is an important task in system design and operation. The gas mixing device should be capable of accurately matching and mixing gas components. The concentration and quantity of protective gas must be adapted to the surface conditions of the molten metal to ensure that the gas consumption is small, and at the same time it is environmentally friendly, safe, and economical. Led Holiday Light,Outdoor Christmas Lights,Christmas Tree Lights,Led Christmas Lights Yuyao Flylit Appliance Co.,Ltd , https://www.flylitlight.com