Load-appropriate arc brazed joint of high-strength sheet steels under metallurgical and geometrical aspects (joint proposal)

弧焊接头的原理、应用可能性和实际应用之间存在着很大的分歧。这归因于目前对弧焊钢板接头在静载荷和循环载荷作用下失效的认识还不够深入，无法进行连接构件的载荷适配设计。对搭接焊缝的几何设计及其局部冶金成分与接头性能之间的关系的基本理解应在本研究项目的范围内进行。到目前为止，还不可能给出导致铜焊缝失效的确切局部过程和失效机制的准确说明。因此，计划中的研究项目的目的是详细调查影响接头静强度和循环强度的主要因素，如钎料强度、附着力、扩散、润湿、几何/力流动以及母材性能的变化；另一个原因是参考基本的失效机理。因此，有可能对失效原因作出更可靠的陈述，并为适用于负载的弧焊接头铺平了道路。这一目标应通过数值模拟模型和冶金模型试验来实现。在考虑上述影响因素的情况下，将弧焊接头分为与强度相关的几何和冶金方面(如间隙填充等)。可以单独检查。随后，再次合并各个结果，从而确定各个因素对整个焊接接头强度(静态、循环)的影响。在固结过程中，还考虑了所考察的影响因素对节理性质的相互作用。目标1代表实现了一种钎焊接头，其特点是在基材水平上具有高的静态强度，同时具有良好的循环强度。目标2代表一种接头的生产，其特点是具有非常好的循环强度，明显高于迄今可能达到的基材载荷的25%，同时仍具有足够好的静态强度。在这里，对这两个目标的综合目标要求是低散射的结果的高可靠性和重复性。以这种方式，可以实现关于主要类型的载荷的更可靠和更坚固的接头。

There is a great divergence between the principle application possibilities and the real applications of arc brazed joints. This is ascribed to the fact that, currently, the knowledge about the failure of arc-brazed sheet steel joints under static and cyclic load is not advanced enough for carrying out the load-appropriate design of the joined components.This fundamental comprehension of the connections between the geometrical design of the brazed seam on lap joint as well as its local metallurgical composition and the joint properties shall be worked out within the scope of the research project. It has, so far, not been possible to give a precise specification of the exact local processes and failure mechanisms which lead to the failure of the brazed seam. Therefore, the objective of the planned research project is the detailed investigation of the main factors which exert influence on the static and cyclic joint strength, such as braze material strength, adhesion, diffusion, wetting, geometry/force flow and the changes of the base material properties; another reason is to make references to the basic failure mechanisms. Thus, a more reliable statement about the failure reasons is possible and the way for the load-appropriate application of arc brazed joints is paved. This objective shall be achieved by means of a numerical simulation model and also by metallurgical model tests. The arc brazed joint is, under consideration of the above-mentioned influential factors, separated into strength-relevant geometrical and metallurgical individual aspects (e.g. gap filling, etc.) which can be examined separately. Subsequently, the individual results are consolidated again in order to determine thus the effects of the individual factors on the strength (static, cyclic) of the entire brazed joint. During consolidation, also interactions of the examined influential factors on the joint properties are taken into consideration.The objective of the research project is subdivided into two sub-ordinate objectives. Objective 1 stands for the achievement of a brazed joint which is characterised by a high static strength on base material level with, at the same time, good cyclic strength. Objective 2 stands for the production of a joint which is characterised by a very good cyclic strength, clearly higher than the hitherto possible 25% of the load of the base material with, at the same time, still sufficiently good static strength. Here, the integrative target requirement to both objectives is the high reliability and reproducibility of the results with low scattering. It is, in this manner, possible to achieve a more reliable and stronger joint with regard to the predominant type of load.