Sr对4045铝合金铸轧板组织和性能的影响

Effects of Sr on microstructure and mechanical properties of 4045 Al-alloy sheets by twin roll casting

通过硬度和拉伸性能检测,并结合金相显微镜和扫描电镜组织观察等分析测试手段,试验研究了变质剂Sr对双辊连续铸轧4045铝合金的微观组织和力学性能的影响。结果表明:未添加变质剂Sr的铸轧板样品中无论是靠近轧辊表面还是板材中心区域α-Al枝晶呈现不规则蔷薇状,共晶Al-Si组织以针状和板条状为主要形态,片层间距较大;添加了变质剂Sr的铸轧板靠近轧辊表面出现了大量的伪共晶组织,在板材中心区域α-Al枝晶被球化,分布均匀,共晶Al-Si组织被细化,片层间距减小,并且存在较少多边形和板条状的初生硅。另外,对比加Sr前后铸轧板材的力学性能表明,添加Sr的板材的抗拉强度提高了12.5%,伸长率提高了7.2%,平均硬度提高了13.1%。

The effects of alloying elements Sr on microstructure of 4045 aluminum alloy were examined by the optical microscopy and scanning electron microscopy, and mechanical properties were studied through hardness measurement and tensile tests in the twin roll casting process. The results show that for the roll-casting sheet sample without Sr,whether it is closed to the roll surface or in the center, α-Al dendrite appears as irregular rosiness, and euteetic Al- Si microstructure exists in the form of needle and lath, and their lamellar spacing is large. When modifier Sr is applied during twin roll casting, massive pseudo euteetic structure appears on the surfaces close to two rolls, α-Al dendrite in the center is spheroidized and uniformly distributed. Eutectic Al-Si phase is refined and lamella spacing is decreased. Moreover, polygons and lath primary Si are found. It is obvious that the tensile strength is increased by 12.5%, elongation is increased by 7.2% and hardness is increased by 13.1% after Sr is added.