CAJ | 학술논문

通过数值模拟及反挤压成形对半固态A357铝合金的密度及力学性能的不均匀性进行研究.结果表明:反挤压制件直壁部的相对密度最小,底部的最大.随着坯料高度的增加,转角处的相对密度需要更长的时间才能达到最高值；随着压力的增加,制件各部的相对密度均增加.模拟结果表明,制件的转角处的拉应力最大,该处产生热裂纹的可能性也最大.通过采用合适的坯料高度及压力,半固态挤压件能够获得细小、均匀的微观组织,且能达到优良的力学性能及硬度.
통과수치모의급반제압성형대반고태A357려합금적밀도급역학성능적불균균성진행연구.결과표명:반제압제건직벽부적상대밀도최소,저부적최대.수착배료고도적증가,전각처적상대밀도수요경장적시간재능체도최고치；수착압력적증가,제건각부적상대밀도균증가.모의결과표명,제건적전각처적랍응력최대,해처산생열렬문적가능성야최대.통과채용합괄적배료고도급압력,반고태제압건능구획득세소、균균적미관조직,차능체도우량적역학성능급경도.
The inhomogeneity of density and mechanical properties of A357 aluminum alloy in the semi-solid state were investigated.Numerical simulation and backward extrusion were adopted to study the preparation of cup shells.The results show that the relative density of the wall is the lowest in samples,and that of the base is the highest.With increasing the billet height,more time is needed for relative density of the corner to reach the maximum value,and the relative densities in every region improve evidently with increasing the pressure.The tensile stress was simulated to be the largest at the comer,and the hot tearings were forecasted to mainly appear at the corner too.By employing proper billet height and pressure,the extruded samples consisted of fine and uniform microstructures,and can obtain excellent mechanical properties and Brinell hardness.