چكيده به لاتين
The aim of this paper is to investigate the microstructural characteristics and the breaking strength of the tensile pieces of aluminum sheet 8011 produced by Twin roll casting method and compare it with the results of a gravel casting sample. Also, the molten metal transfer system in the Twin roll casting process is analyzed in order to obtain the relationship between the quality of the production sheet and the Twin roll casting conditions. In order to achieve these goals, sheets of aluminum alloy 8011 were produced using two different casting methods, including Twin roll and gravel casting, and their properties and microstructure were investigated. The sheets were then homogenized and rolled. The microstructure and fracture profile were evaluated using optical microscope and scanning electron microscopy and mechanical properties using tensile and microhardness tests. Also, the melt flow in the melt transfer system for both casting methods was simulated and evaluated using ProCAST 2016.1 software.
The difference in the cooling rate and the amount of plastic deformation created on the surface and center of the sheet during the dual-roll casting process has led to a discrepancy and heterogeneity in the microstructure. In different conditions of casting, homogeneous and rolled, tensile strength of 135, 101 and 201 MPa for Twin roll casting sheet and 100, 97 and 184 MPa for gravity casting sheet and percentage of elongation of sheet length Twin roll casting is 23.3, 23.8 and 7.1 percent, and for gravity die casting 19.2, 24 and 4.8 percent. The velocity of the melting in the nozzle output of the dual-screwdriving machine is less than 0.5 (m / sec). In accordance with the simulation results, due to the slow flow of the melt at the outlet of the nozzle, the probability of the presence of doped oxide layers in the sheet is very small, there was no effect on the presence of oxide layers at the breakage. The differences in the characteristics of the microstructure, including the grain size, the distance between the secondary dendritic arms, the size of the particles and the shape of them, have a significant effect on the size and number of cavities on the surface of the breakage and the softness of the samples, resulting in more softness The alloy is in the form of a Twin roll casting to gravity casting.
Keywords: Twin roll casting, Aluminum alloy 8011, Melt transfer system, Breakage section, Oxide layers
