Semi-continuous-cast magnesium alloy ingots of

Title: Semi-continuous-cast magnesium alloy ingots of Author: Zhao Kaiyang Degree-granting units: Chongqing University Keywords: semi-continuous casting;; secondary cooling water;; casting speed;; secondary dendrite arm spacing;; macrosegregation Summary:

Magnesium alloy light weight, strength and specific stiffness, damping, good, able to withstand large impact loads, etc., in many areas have been more widely used. In order to reduce deformation of magnesium alloy ingot defects, reduce the ingot macrosegregation increased the levels of deformation of magnesium alloy semi-continuous-cast ingot quality, has the Magnetic lifter effect of the hot top casting, continuous casting and electromagnetic casting and other new technologies, but The new process equipment is more complex, costs have increased, the popularity of far less than traditional semi-continuous casting.

This as the National Key Basic Research Program "973", "semi-continuous ingot magnesium alloy characterization and quality evaluation of the organization," the part, the proposed optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction ( XRD), differential thermal analyzer (DSC) and other means of detection, by considering several typical wrought magnesium alloy ingot in the traditional semi-continuous casting process, the different secondary cooling water, casting speed and size of the solidified ingot segregation of alloying elements and the influence of the macro, as well as different levels of rare earth Ce on ZK20 magnesium alloy ingots semi-continuous organizational impact assessment of a variety of conditions, the merits of the slab organization for large-scale semi-continuous magnesium alloy casting provide guidance on the production process.

The results show that:

① In the traditional semi-continuous casting conditions, AZ31 magnesium alloy ingots organization to some extent, with the secondary cooling water and casting speed increases gradually refined, when the secondary cooling water 58L/min, casting speed 16cm/min, have access to a small size, homogeneous of Φ90AZ31 magnesium alloy semi-continuous ingot.

② by comparing the diameter of the AZ series of magnesium alloy semi-continuous ingot cross-section of tissue obtained, Φ100 magnesium alloy ingot ingot showing a small central organization, the edge of thick tissue anomalies, other organizations are the diameter of the ingot typical ingot organizational characteristics, the center's organizational thick, while the secondary cooling water from near the edge of a small organization; diameter Φ165, Φ170 magnesium alloy ingot obvious thick edge region columnar grain zone; with the diameter of the ingot http://www.999magnet.com/products/131-magnetic-lifter increase in ingot more uniform radial organization, but when the diameter of Φ500, AZ91 ingot size larger ingot central region received almost no secondary cooling water chilling effect, the grain was coarse, Radial organization was significantly different, the overall uniformity of variation.

③ AZ by analyzing the diameter of the Department of magnesium alloy semi-continuous vertical section of the organization come ingot, magnesium alloy ingot vertical section of the organization compared to the same cross-section of organizations, not much difference, but close to the edge of the ingot The longitudinal section at the secondary cooling water due to the impact of one-way thermal effects, there are a certain amount of long dendrites.

④ AZ series magnesium alloys in the semi-continuous solute segregation of Al and Zn as the ingot diameter decreases, a comprehensive analysis of various diameter ingot, Φ300AZ31 magnesium alloy ingot cross-section of organizations and solute elements in the radial The most uniform distribution of solute elements in the smallest degree of macro-segregation.

⑤ rare earth elements Ce has refined the role of magnesium alloy. To Mg-1.5Zn-0.2Zr semi-continuous mass percentage of magnesium alloy by adding 0.3% Ce can get the most precipitate dispersion, uniform refinement of the best organizations; adding Ce after the Mg-1.5Zn-0.2Zr magnesium alloy semi-continuous ingot from the center to the edge of the intragranular precipitates gradually reduced or even disappear. Degree Year: 2010