How to refine the crystallization of cast aluminium bars
Thus, the grain size of the alloy decreases by two times, and the grain boundary area increases twice as much. The impurity content in the unit area of the grain boundary will be reduced by one time.
First, add refiners such as aluminum, titanium, boron, silk, and second to increase cooling rates, such as water cooling.
Grain refining is one of the important processes in aluminum alloy casting and halo casting, and also one of the most effective measures to solve the casting defects such as porosity, coarse grain, bright crystal, feather crystal and crack. In the alloy casting, are non-equilibrium crystallization, all the impurities (including alloy elements) most concentrated at the grain boundaries, the smaller the grain boundary area, the greater the impurity elements (or alloy) uniformity is high. The impurity elements, high uniformity, can reduce its harmful effects, even small amounts of impurities harmful variable as beneficial; surface of alloy elements, high uniformity, can play a greater alloying elements capable of making full use of resources to achieve. The role of grain refinement, grain boundary area enlargement and element homogeneity can be explained by the following calculations. 1 and 2 metal blocks assuming the same volume of V, which is composed of cube grain, grain length of metal piece 1 for 2a, 2 of the length of a, then the metal piece 1 grain boundary area: metal piece 2 grain boundary area: metal block 2 block 1 of the grain boundary area is 2 times of metal.
