Statistical analysis method of solid-liquid segregation in semi-solid die-casting thick wall castings

In the process of analyzing the solid-liquid segregation, in order to identify the bright white cxal grains and the dark liquid phases in the gold phase, Keller reagent was used to corrode the samples for 15 seconds. The treated samples were observed under the metallographic microscope. The solid phase dominated by A1 grain and the liquid phase dominated by Si could be clearly observed.

In order to observe the solid-liquid metallographic structure comparison from the edge to the center, Photoshop software is used to splice 25X metallographic photos of the corroded samples from the edge to the center along the radial direction. Fig. 2 is an example of the photos after splicing. In the process of counting the liquid fraction, the above-mentioned metallographic mosaic photos after corrosion are equidistant divided into 1 from the edge to the center Three regions (corresponding to the number of subsequent radial mechanical properties samples) were used Plus counted the bright white a-Al in the photo according to the method in Fig. 3, and obtained the corresponding liquid phase fraction by subtracting the solid phase fraction from the total amount of 1. Three metallographic stitches from the edge to the center were taken from each position of each sample. The statistical average value was taken as the radial liquid phase statistical value variance as the radial liquid phase statistical error.