Influência da pressão na modificação estrutural e propriedades mecânicas da liga AI-7%Mg obtida através do processo Squeeze Casting

Abstract

The Squeeze Casting process is an innovative process within the process of casting, in which the cast metal in the liquid is solidified under pressure within a closed metal ingot by a punch. "Sound Casting” is the name given to the castings of good quality. A disadvantage of conventional casting processes is the formation of bubbles, porosity, Schinkage defects and macrosegregations that directly influence the mechanical properties of cast products. Thus, this study looked for to analyze the influence of pressure on the structural change of three binary alloys Al-Mg system in low compositions, the liquid metal solidified under pressure of: 10, 20, 40, 80 and 120 MPa, and solidification without pressure. From the data obtained in this work could produce a chart that allows trial provides for the macrostructure of the binary alloys Al-Mg obtained from Squeeze Casting process. It was noted that there was a large influence of pressure on the microstructure of parts reducing around 50% the values of Dendritic Spacing Secondary (DAS) between the ingots obtained for pressures of 120 MPa and the condition without pressure. Respectively to the pressures mentioned above were obtained the following values of the DAS: 18.06 µm, 16.20 µm, 16.19 µm, 16.18 µm, 15.46 µm and 33.46 µm. Subsequently the results of structural changes were correlated with values obtained for the Density, Ultimate Limit of Tensile and Microhardness.