Process chains for co-extrusion and heat treatment of asymmetrical compounds made of alumini-um and titanium

新的应用项目的目的是开发具有连续粘结增强元件的复合型材的制造工艺链，包括材料科学和生产技术的必要关系，根据研究和初步工作的状况，这些关系可以缩小为：1.通过共挤出形成材料结合为了避免夹持和撕裂加强元件，摩擦接触仅限于模具区域。为此，刚性加强元件在清洁和预热的条件下从外部进给到打包室中，并从挤压铝型材中拉出。通过使用ECAP模头，可以实现侧向进料所需的挤压型材偏转，该模头还可以生产非对称复合型材。与前体项目相比，无氧化物扩散层需要通过完全用惰性气体吹扫的清洁和预热装置来实现。因此，必须考虑压制参数以及外部进料增强元件的表面条件及其预热条件，对ECAP复合共挤出有更深入的理解。2.尺寸和形状变化沿着工艺链的发展由于复合型材的不对称性和非常不同的热膨胀系数，可以预期显著的尺寸和形状变化。关于挤压复合型材变形补偿方法的信息在文献中找不到，因此，为了找到合适的变形补偿方法，必须对挤压和热处理过程中尺寸和形状变化的发展有更深入的了解.热处理过程中结合区和结合性能的演变项目第一阶段的结果表明，结合强度在很大程度上取决于由扩散引起的结合区。此外，还必须考虑铝作为两种材料中较弱的材料的强度。因此，热处理是调整最终粘结性能的重要工艺步骤。热处理过程中粘结性能的建模工作尚不清楚，因此，根据热处理条件，必须深入了解粘结区的演变和改性，以便对所得粘结性能进行建模。

The aim of the new applied project is to develop process chains for manufacturing com-pound profiles with continuous bonded reinforcing elements, including the necessary relationships of materials science and production technology.Based on the state of research and preliminary work these relationships to be developed jointly can be narrowed as follows:1. Formation of a material bond by co-extrudingIn order to avoid clamping and tearing of the reinforcing element, the frictional contact is only re-stricted on the region of the die. For this, the rigid reinforcing element is fed in cleaned and pre-heated condition from outside into the bale chamber and dragged from the extruded aluminium profile. The required deflection of the extruded profile for lateral feeding can be achieved by using an ECAP die that also enables the production of asymmetric compound profiles. Compared to the precursor project an oxide-free diffusion layer shall be achieved by means of the cleaning and pre-heating device that is completely purged with inert gas.Thus, a deeper understanding of the co-extrusion of compounds by means of ECAP has to be developed in consideration of the pressing parameters as well as the surface conditions of the externally fed reinforcing elements and its pre-heating conditions.2. Development of the dimensional and shape changes along the process chainDue to the asymmetry of the compound profiles and the very different thermal expansion coeffi-cients significant dimensional and shape changes can be expected. Information about distortion compensation approaches for extruded compound profiles could not be found in the literature.Therefore, in order to find suitable distortion compensation approaches a deeper insight has to be gained regarding the development of the dimensional and shape changes during extrusion and heat treatment.3. Evolution of the bonding zone and bond properties during heat treatmentThe results of the first project phase show that the bond strength largely depends on the bonding zone caused by diffusion. Additionally, the strength of aluminium as the weaker of the two materials has to be considered as well. Therefore, the heat treatment is a significant process step for adjusting the final bond properties. Works, which deal with modelling of the bond properties during heat treatment, are not known.Hence, depending on the heat treatment conditions an indepth insight into the evolution and modi-fication of the bonding zone has to be gained that enables a modelling of the resulting bond properties.