双阶段均匀化对铸轧Al-Zn-Mg-Cu合金Al_(3)Zr析出的影响

Two-Stage Homogenization of Al-Zn-Mg-Cu Alloy to Improve Al_(3)Zr Precipitation Processed by Twin-Roll Casting

研究了均匀化制度对双辊铸轧Al-Zn-Mg-Cu合金Al_(3)Zr相析出行为及再结晶的影响,以及Al_(3)Zr析出和再结晶程度对合金力学性能和耐晶间腐蚀性能的影响.结果表明,相比于传统的单阶段均匀化,双阶段均匀化的第一阶段为Al_(3)Zr的析出提供了更大的形核驱动力和更多的非均匀形核质点,促进了Al_(3)Zr的析出.此外,不同的升温速率对Al_(3)Zr的析出也有影响,缓慢的升温速率有利于细化Al_(3)Zr尺寸,增加Al_(3)Zr的数量密度和体积分数.固溶处理时,Al_(3)Zr相f/r值的变化导致了不同的再结晶抗力,因此在T6处理后双阶段均匀化的试样再结晶组织比例降低,大角度晶界数量减少.Al_(3)Zr相f/r值以及显微组织的变化对合金力学性能的影响较小,显著提高了合金的抗晶间腐蚀性能.

This study focused on the effect of homogenization on precipitation behavior and recrystallization of Al-Zn-Mg-Cu alloy with twin roll casting(TRC).Furthermore,the influences of Al_(3)Zr precipitation and recrystallization levels on mechanical properties and intergranular corrosion(IGC)resistance were evaluated.The results showed that compared to the single-stage homogenization,the first stage of two-stage homogenization provides higher driving force and greater number of heterogeneous nucleation sites,which enhances the precipitation of Al_(3)Zr.In addition,different heating rates also affect the precipitation of Al_(3)Zr.The slow heating rate is beneficial to refine the size of Al_(3)Zr and increases the quantity density and volume fraction of Al_(3)Zr particles.During the solution treatment,variations of f/r ratio of Al_(3)Zr phase leads to different recrystallization resistance,so the proportion of recrystallization structure and the number of large angle grain boundaries of the samples homogenized after the T6 treatments decrease.These microstructures and the corresponding distributions of Al_(3)Zr slightly affected the mechanical properties,while they significantly improved the intergranular corrosion resistance.