Magnesium castingThe peculiarity of melting magnesium alloys is to protect them from oxidation and burning, to which they are very apt. Depending on the magnitude and specificity of the production of magnesium alloy smelting is carried out in crucible furnaces of removable and fixed crucibles, in reflection and induction furnaces of industrial frequency.
The melting was carried out in a fixed of removable cast or welded steel crucibles. For the initial charge materials make high demands on the purity of the surface. To prevent oxidation and sunbathing, melting of magnesium alloys is carried out in a medium with a protective gas atmosphere and with the use of coating flux.
When melting magnesium alloys, the covering flux often performs the tasks of refining flux. During the melt of flux in the melt in the alloy, wetting of nonmetallic inclusions occurs. Due to a higher density in comparison with the melt, the flux is gradually deposited on the bottom of the crucible, cleaning of melt inclusions.
To reduce the possibility of oxidation and ignition of the active magnesium in the melt form in the mold and core sands, protective additives - sulfur-boric acid mixture stem is introduced, along with additives based on fluoride salts and urea in the molding mixture.
For the preparation of molding and core mixtures, quartz sand, thin and bold is used. The amount of circulating mixture into the moldable mixture is 85-97%, and fresh materials - 15.3%.
For chill casting, magnesium alloys ML5, ML6, ML 10, ML 12, ML 15 are used. The features of the process are the creation of a protective atmosphere, preventing oxidation and fire magnesium melt, setting profits increased in size to compensate for the high volume shrinkage alloys, and fever fills for better filling of the mold.
To improve the mechanical properties of castings of magnesium alloys, heat treatment is applied.