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2021.10.27
In the production of high-end zinc alloy die castings, a certain proportion of product defects and sudden product price rise accidents often occur. Therefore, the occurrence rate of pores and gas shrinkage defects shall be minimized, and the defects shall be reduced and solved as soon as possible. Read this guide and learn how to control & reduce the content of hydrogen and nitrogen in zinc alloy die castings.
As long as the furnace is operated under normal parameters, the relationship between the gas in the molten pool space, the molten liquid and its surrounding environment should be easy to understand. Liquid metals are very active and form compounds on their surfaces. The basic principle is that the equilibrium relationship between the three is destroyed, and they are in an equilibrium state with the surrounding liquid. The influence between content and molten liquid surface. It is concluded that the formation core of pores is closely related to liquid zinc and solidification.
If the content of hydrogen and nitrogen in liquid zinc is too high, pinholes will be formed in zinc alloy die castings. When the solidified zinc alloy die castings are precipitated, the reason is due to the decrease of gas solubility during solidification. The gas content in the melt changes according to the melt temperature and treatment method. This change is also reflected in the filling process of liquid zinc. The hydrogen and nitrogen formed by the reaction at the cavity interface are released from the molding material and can also be melted into the liquid zinc, which is very interesting. From charging melting to pouring, and then to cavity filling. In each stage of the production chain, the change of equilibrium parameters reflects the change of gas content (including hydrogen and nitrogen).
The melting process is not caused by extreme values and control confusion from hydrogen. It is important that the changes of hydrogen and nitrogen are mainly the melting process. Temperature and zinc discharge tank have little influence. The content of hydrogen and nitrogen is also affected by pouring. The gas content in molten zinc is different before pouring into the mold, which has an impact.
The molten zinc in cupola has higher nitrogen content and lower hydrogen content than that in induction furnace. The preheating of charge will be lower than that of induction furnace (hydrogen content), but their content is not always lower than that of cupola zinc water. Both hydrogen and nitrogen increased during mold filling, and the increase of hydrogen content was stronger.
The molten zinc does not work until it enters the mold. The same work should also include the turbulence in the mold filling process, the formation and occurrence of gas in the solidification process, and part of the work should also be placed in various conditions for absorbing gas in the mold. In order to obtain the information and structure of the solidification process of cast zinc.