Influence of Mg and Si Content in Aluminium Alloys on Severe Plastic Deformation Behaviour during Solid-State Coating Deposition using Friction Surfacing

铝合金中 Mg 和 Si 含量对摩擦堆焊固态涂层沉积过程中严重塑性变形行为的影响

基本信息

批准号：
323162991
负责人：
Dr.-Ing. Stefanie Hanke
金额：
--
依托单位：
Lehrstuhl für Werkstofftechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/323162991?language=en
关键词：
Influence Mg Si Content Aluminium

项目摘要

Dynamic recrystallization has a major influence on process characteristics and material flow in friction-based solid state joining techniques. In addition to general material properties, a.o. heat capacity and high temperature strength, dynamic microstructural processes, e.g. dislocation movement, grain boundary migration, formation of substructures or precipitation of phases, have a strong effect on the acting flow stresses. The correlation of such microstructural mechanisms and the material behaviour during Friction Surfacing or similar solid state joining techniques has not been systematically investigated up to today. Small changes in the content of alloying elements, e.g. in Aluminium alloys, require significant adaptations of the process parameters, which are to date established by empirical or statistical approaches.During Friction Surfacing (FS), a stud made from the coating material, rotating around its longitudinal axis, is pressed onto the substrate. After a short heating phase (< 2 s), the stud material adheres to the substrate surface and the rotational relative motion is accommodated by shearing the softened stud material. When an additional translational motion is superimposed, the plastified stud material is sheared off the stud and deposited onto the substrate as a coating layer. The heat required for the process is solely generated from plastic deformation.For FS of Aluminium alloys, rotational speeds up to 4000 1/min are applied, process temperatures reach approximately 80% of the melting temperature and cooling rates range at 30 K/s. Although strain and strain rates can only be estimated from the dimensions of the shear layer, obviously the deformation conditions are extreme. The available knowledge of dynamic recrystallization and flow stresses under such severe conditions is very limited, and only few publications on Gleeble-tests and high-pressure-torsion experiments at high temperatures provide some clues.In the scope of this project 6 custom-made Aluminium alloys are processed by FS. Each of these alloys only differs in its content of Mg or Si, allowing a direct comparison and therewith the investigation of the effects of those alloying elements on the material behaviour. The Si content will be raised up to 17.5 wt%, providing undissolvable hard phases during processing, which will further influence the deformation and recrystallization mechanisms. Besides examining process forces and coating geometry, XRD, EBSD and TEM investigations of the microstructural mechanisms of plastic deformation will be carried out, and correlated with the material behaviour during FS.FS typically results in very low grain sizes and spheroidization of hard phases. The mechanical properties of the obtained coatings, which are relevant for a potential industrial application of the FS process to generate coatings via severe plastic deformation, will be evaluated through micromechanical tests in the scope of this project.

动态重结晶对基于摩擦的固态连接技术中的过程特性和材料流有重大影响。除了一般材料特性，A.O。热容量和高温强度，动态微观结构过程，例如脱位运动，晶界迁移，子结构的形成或相位的降水对作用流应力有很大影响。迄今为止，尚未系统地研究这种微观结构机制与摩擦表面或类似固态连接技术的材料行为的相关性。合金元素的含量的小变化，例如在铝合金中，需要对过程参数进行显着适应，这是通过经验或统计方法确定的。摩擦效果（FS），一种由涂层制成的螺柱，围绕其纵轴旋转的螺柱，被压在底物上。在短加热阶段（<2 s）之后，通过剪切软化的螺柱材料来容纳螺柱材料粘附到底物表面和旋转相对运动。当额外的翻译运动被叠加时，将填充的螺柱材料从螺柱上剪切并沉积在基板上作为涂料层。该过程所需的热量仅由塑性变形产生。对于铝合金FS，施加了高达4000 1/min的旋转速度，过程温度约为熔融温度和冷却速率的约80％，范围为30 K/s。尽管只能从剪切层的尺寸估算应变率和应变率，但显然变形条件是极端的。在如此严重的条件下，动态重结晶和流动应力的可用知识非常有限，在高温下，只有很少的关于gleble测试和高压扭转实验的出版物提供了一些线索。这些合金中的每一种仅在其Mg或Si的含量上有所不同，可以直接比较，从而研究这些合金元素对材料行为的影响。 SI含量将提高到17.5 wt％，在加工过程中提供不可分解的硬相，这将进一步影响变形和重结晶机制。除了检查过程力和涂层几何形状外，还将进行塑性变形的微结构机制的XRD，EBSD和TEM研究，并将与FS.FS期间的材料行为相关，通常会导致非常低的晶粒尺寸和非常低的硬性相位化。所获得的涂层的机械性能与FS工艺的潜在工业应用有关，以通过严重的塑性变形生成涂料，将通过该项目范围的微机械测试评估。