3A21铝合金半固态坯料制备工艺研究

以3A21铝合金为研究对象,将等径角挤压工艺与等温处理工艺相结合,从实验角度研究其中的工艺参数对半固态组织尺寸形貌的影响。采用Bc路径进行ECAP3道次处理,然后在660℃下保温20,25,30min,得到27个试样的半固态组织。结果表明,随着挤压道次的增加,晶粒尺寸减小,变形更加均匀,并且累积变形能的增多,也为后续半固态等温处理提供了更好的应变诱导条件;保温时间越长,半固态组织演化越完全,晶粒球化越完整,但晶粒尺寸会随着保温时间的延长而长大。最后得出最佳工艺参数匹配:室温下沿Bc路径等径角挤压3道次,660℃下保温25min;最终半固态坯料显微组织的平均等积圆直径d=83.7μm,平均形状系数Fc=0.84。

Study of Fabrication of Semi-solid Billet of 3A21 Aluminum Alloy

Equal channel angular pressing and isothermal treatment were combined and the influence of technological pa-rameters on size and pattern of semi-solid microstructures of 3A21 aluminum alloy was analyzed in the view of experiments. Twenty-seven samples were obtained after 3 passes ECAP under route Be and 20, 25,30 min holding under the temperature of 660 ~C. The results indicate that, with the increment of ECAP passes, size of gains becomes smaller, deformation of micro-structure becomes more uniform, and the more accumulation of deformation energy creates a favorable strain inducement con-dition for subsequent isothermal treatment in semi-solid state; gains spheroidize better and gain size becomes larger when the heat holding time elongates. In conclusion, the best technology parameters are as follows： ECAP route Bc, 3 passes, holding temperature 660 ℃, holding time 25 min. The average gain size is 83.7 μm, and the average shape factor is 0.84.