Исследование влияния однородности зеренной структуры на показатели пригодности к операциям листовой штамповки сплавов АМг2 и АМг6

The quality of products made of sheet aluminum alloys strongly depends on the technological features of the sheet stampingprocess, as well as on the structure of sheet semi-finished products. The grain sizeand grain structure uniformity are among the key structural features that influence stampability. A method is proposed and the homogeneity of the grain structure is evaluated. Stampability of Al2Mg and Al6Mg aluminium alloys was evaluated based on measurements of the spring back index, minimum bending radius, stampingratio, and Martensstrain index. Cold work (with a strain degree of 20 %) and subsequent recrystallization annealing at temperatures of 250, 350 and 450 °C for 1 h were used to obtain a grain structure of (26,8 Ѓ} 7,4)÷(126 Ѓ} 43) μm (Al6Mg alloy) and (120 Ѓ} 11)÷(264 Ѓ} 130) μm (Al2Mg alloy) in size. As a result of processing, the effect of the initial grain sizewas revealed: the coarser structure of the Al2Mg alloy led to a larger grain sizeafter strain and annealing. It was found that an increase in the grain sizein both alloys leads to an increase in the Martensindex and a decrease in the stampingratio, which indicates higher stampability of the alloys in the drawing operations of sheet stamping. In the Al2Mg alloy, an increase in the grain sizeleads to a decrease in the spring back index by 1,5–1,7 times, and an increase in the minimum bending radius. In the Al6Mg alloy, an increase in the grain sizeleads to an increase in the spring back index by 1,1–1,2 times, and a decrease in the minimum bending radius. The Al6Mg minimum bending radiusremains higher compared to Al2Mg regardless of the grain size. Grain sizeinhomogeneity in the Al6Mg alloy causes an increase in the Martensindex and minimum bending radius, and a decrease in the stampingratio. In the Al2Mg alloy, grain sizeinhomogeneity causes an increase in the Martensindex and minimum bending radius, and a decrease in the stampingratio. For the spring back index, the increase in grain sizeinhomogeneity causes a high scatter of data. In the Al6Mg alloy, the low annealing temperature led to the preservation of the non-recrystallized structure, which influenced the decrease in stampability.