Antonia Schram

Low Heat Joining – Manufacturing and Fatigue Strength of Brazed, Locally Hardened Structures

Low-heat brazing as a joining option for high strength steel sheets under cyclic load is still a challenge for manufacturing. For application arc brazing to locally hardened, high strength steel sheets a material specific manufacturing concept is needed to ensure a quality-related, reliable and reproducible processing. Thus the interaction of brazing parameters, metallurgical properties, types of brazed seams and different arc-processes under cyclic load were investigated. This should extinguish the base for an extended application of arc-brazed joints at cyclic loaded, high strength, property adjusted structures.

Systematic Design Approach to the Development of High-Strength, Locally Adapted Structures with the Aid of the Finite Element Design (FED) Method

Design engineers can choose from a large variety of materials in order to fulfill a certain function. In those fields of application with a lower level of complexity, it is often sufficient to manufacture the entire component in a “monolithic” manner from one single material. Concurrent, partly contradictory and, most probably, local requirements that must be fulfilled by a component often make material selection more difficult. As a consequence, it is often necessary to use several different materials with a local and functional orientation, which is a part of the multi-material design strategy. The potential of different materials can be used most effectively if this information is made available to the design engineers as early on in the design process as possible. The aim of the SFB 675 sub-project C7, therefore, is the development of a systematic design approach (Finite Element Design, FED) that focuses on finite component elements. As a result, the potential of the optimization of local properties is taken into consideration, and the interaction between the materials, production processes, and design can all be described.

Investigation of the Process- and System-Induced Activation of Material Reactions during Discontinuous High-Frequency Welding

Besides weldable component geometries for the high-frequency welding process also possible process and system induced activated material reactions during discontinuous high-frequency welding are presented in this paper. Among others such material reactions can be a locally limited thermal influence on the base metal, defined plastic derformations during the upsetting process as well as grain refinement in the weld seam, comparable to thermomechanical treatment during rolling for increasing strength or ductility.

Low Heat Joining – Manufacture and Fatigue of Soldered Locally Strengthened Structures

The advantages of low heat joining techniques, such as low distortion and little influence on the local material properties due to the low introduced amount of heat, shall be made usable for the manufacture of high strength structures by increasing the process reliability. The dependency between the parameters of the joining process, the seam geometry, the type of solder, the load type und the fatigue life especially of soldered structure with local strengthening shall be examined to allow a calculative estimation of the part’s life.