Development of high-strength AlZnMgCu-castalloys for light weight constructions - studies of mechanisms of hot tearing formation during solidification

用于轻质结构的高强度 AlZnMgCu 铸合金的开发 - 凝固过程中热撕裂形成机制的研究

• 批准号: 275013255
• 负责人: Professorin Dr.-Ing. Babette Tonn
• 金额: --
• 依托单位: Abteilung Gießereitechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/275013255?language=en
• 关键词: Development; strength; AlZnMgCu; castalloys; light

For the objective of reducing the fuel consumption and the subsequent reduction of polluting emissions the automotive as well as the aviation industry have to choose innovative approaches in light-weight construction, which are connected with the development of new light-weight materials. In this perspective high strength AlZnMgCu-alloys with ultimate tensile strength above 600 MPa have a very high development potential.Nowadays, AlZnMgCu-alloys are mainly used as forging alloys, because these materials are very sensitive to hot cracks which limits their ability for the usage of gravity die casting or high pressure die casting. By accurately knowing the mechanisms of the formation of hot cracks in AlZnMgCu-alloys it will be possible to improve their behavior and to establish these alloys as trendsetting casting material for light weight construction.The submitted research project consists of five sub-ordinate targets:1. It will be investigated if the thermal analysis with two thermocouples is a proper method to predict the end of mass respectively interdendritic feeding in AlZnMgCu-alloys by the determination of the Dendritecoherence- and the Rigiditytemperature. This will be accomplished by the comparison of the results of thermal analysis and those of rheological testing.2. A measurement device will be constructed which allows to measure the start temperature of solidification contraction, the start temperature of the formation of contraction strains as well as the temperature of hot cracks in AlZnMgCu-alloys.3. The hypothetical assumptions for the calculation of CSC- and TFR-criteria should be replaced with experimental profound knowledge of the Dendritecoherence- and the Rigiditytemperature. The resulting improvement of CSC- and TFR-criteria will make it possible to predict the hot crack tendency of an (AlZnMgCu-) alloy.4. It will be investigated by thermodynamic calculation of solidification paths if there are other criteria than CSC and TFR for the prediction of hot crack tendency, for example the magnesium content of the residual melt at the end of solidification or the calculated amount of eutectic phases.5. Another focus is the comprehensive investigation of the influence of casting parameters (mould and casting temperature) and grain refinement for the formation of hot cracks. This will result in new high strength aluminum alloys for light weight construction on the basis of AlZnMgCu with excellent hot crack stability.

为了降低燃料消耗和随后减少污染排放的目标，汽车和航空工业必须选择与新型轻质材料开发相关的轻质结构创新方法。目前，AlZnMgCu合金主要用作锻造合金，因为这些材料对热裂纹非常敏感，这限制了它们在重力铸造或高压铸造中的应用。通过准确地了解AlZnMgCu合金热裂纹形成的机理，将有可能改善其性能，并将这些合金确立为轻质结构的趋势铸造材料。 将研究用两个热电偶的热分析是否是通过确定枝晶相干温度和刚性温度来预测AlZnMgCu合金中的质量终点和枝晶间补料的适当方法。这将通过热分析结果与流变试验结果的对比来实现. 将构建一个测量装置，其允许测量凝固收缩的开始温度，收缩应变形成的开始温度以及AlZnMgCu合金中的热裂纹的温度。 计算CSC和TFR标准的假设假设应被枝晶相干性和刚性温度的实验深刻知识所取代。CSC和TFR准则的改进将使预测（AlZnMgCu-）合金的热裂纹倾向成为可能. 通过凝固路径的热力学计算，研究是否存在除CSC和TFR之外的其他准则来预测热裂纹倾向，例如凝固结束时残余熔体中的镁含量或共晶相的计算量. 另一个重点是全面研究铸造参数（模具和铸造温度）和晶粒细化对热裂纹形成的影响。这将导致在AlZnMgCu的基础上具有优异的热裂纹稳定性的用于轻质结构的新型高强度铝合金。