【摘要】 研究了不同压铸条件下Al-5Mg-2Si-Mn铝合金压铸坯锭的等温半固态组织演变过程。与重力铸造相比,铸态压铸实验合金的α-Al初始晶粒细小;且压射压力越大,晶粒尺寸越小,组织中的畸变能越多。研究表明,重力铸造与压铸实验合金的半固态等温组织演变过程相似,但压铸合金的演变进程更快。不同压射压力压铸实验合金坯锭的半固态等温热处理过程中,α-Al晶粒直径与等温时间之间符合关系式■,粗化速率常数随压射压力的增大而减小。对于相同压射压力的压铸合金坯锭,随等温温度的升高,半固态组织的α-Al的晶粒尺寸增大,粗化速率常数减小。在相同等温时间条件下,压铸合金比重力铸造合金等温半固态组织的固相体积分数小,晶粒的粗化速率低。研究确定了实验合金的优化半固态等温处理工艺为620℃等温20 min。更多还原

【Abstract】 Semi-solid isothermal heat treatment microstructural evolution of die cast Al-5Mg-2Si-Mn alloy with different injecting pressures was studied.The averageα-Al grain size of as-cast die casting experimental alloys was smaller than that of gravity casting,and it decreased while microstructure distortion energy increased with the increase of the injecting pressure.It was found that semi-solid microstructural evolution process of die-cast alloy was similar to,but faster than that of gravity casting.The results from regression analysis show that the relationship between the averageα-Al grain diameter and the isothermal holding time fits the formula ■,and the coarsening rate(K)is decreased with the increase of the injecting pressure.For the fixed injecting pressure,the averageα-Al grain size of the experimental alloy increased while the K decreased with the increase of the isothermal holding temperature.For the fixed isothermal holding time,the solid fraction andα-Al grain coarsening rate of die-casting alloy were lower than those of gravity.The appropriate semi-solid isothermal heat treatment parameters of the die casting experimental alloy were determined to be 620°C for 20 min.更多还原