半固态扩展挤压A2017合金工艺过程的模拟与实验

Simulation and Experimental Research of the Extending Extruding Process of Semisolid A2017 Alloy

半固态扩展挤压A2017合金过程中,从扩展腔中心区域向两边侧壁合金速度逐渐减少,有时在从中心向两边侧壁的中间区域出现涡流的过渡区;设计无台阶α且较小倾角θ的扩展挤压模较为合理,在定径带断面的长向与宽向上尺寸应尽量相等;浇注温度高于790℃时,由于合金与模具的粘结以及热应力的作用使制品表面出现裂纹,而浇注温度低于690℃时,制品表面产生浪形,比较合理的浇注温度为710～750℃;通过控制浇注温度得到了表面状态良好的断面尺寸为14mm×25mm的A2017扁型材,其断裂强度比标准值提高了100MPa,延伸率提高了29%·

It is shown that mass flow velocity decreases gradually from the center to sides of mould wall during the extending extrusion process of semisolid A2107 alloy. In the middle of the way from the center to the side of the mould, there often is a transitional turbulence zone. These indicate that it is best to design a mould with smaller θ and without step α. Two sides of negative mould should be as equal as possible. When pouring temperature is higher than 790?℃, due to thermal stress and alloy adhering on the mould, cracks would occur on the product surface. If pouring temperature is lower than 690?℃, waves occur on the surface. The proper pouring temperature should be 710～750?℃. A2017 product of 14?mm×25?mm rectangular transection was achieved with fine surface. The fracture strength and elongation of the product are 100?MPa and 29% higher than normal requirements respectively.