P 820 - Development of solar absorbers in steel construction based on partially clad hybrid semi-finished products

P 822 - Use of the laser beam-MSG hybrid welding process on longitudinally welded large-diameter pipes of grade API-X80/ -X100 to increase toughness and efficiency A significant proportion of modern oil and gas pipelines are made from longitudinally welded large-diameter pipes in API steel grades X65 (L450, 1.8726) and X70 (L485, 1.8727). Constantly increasing natural gas and crude oil production rates in conjunction with minimising wall thickness or increasing operating pressure will in future require corresponding material substitutions with modern higher-strength materials, such as API-X80 (L555, 1.xxxx), X100 (L690, 1-xxxx) and X120, with sufficient strength and toughness. The submerged arc welding process is used to weld these pipes. The entire pipe length is first welded with a continuous MSG tack weld. To increase economic efficiency, this process step is to be replaced by the laser beam-MSG hybrid welding process. For the safe operation of large-diameter pipes, the required impact strength of the welded joint must be observed in addition to the strength properties. Against this background, the primary research objective of this research project was to define and systematically investigate the achievement of sufficient toughness in the temperature range of -60°C and -40°C with economic process parameters. Suitable filler materials (solid wire and flux-cored wire electrodes) were identified for the laser-MSG hybrid welding of the aforementioned high-strength pipeline materials and systematic studies were carried out on the dependence of toughness on solidification behaviour and the achievable mixing depth. Increased economic efficiency when using laser hybrid technology is seen primarily in the modified seam preparation. A constructive change in the joint shape leads to a reduction in the seam volume and thus to a considerable reduction in production costs, because in this case the amount of filler material required to fill the seam is reduced. Based on demonstrators produced, an approx. 2.7-fold reduction in the seam cross-section and thus the required quantity of filler material is demonstrated. The IGF project 16415 N of FOSTA -Forschungsvereinigung Stahlanwendung e.V., Düsseldorf, was carried out at the Federal Institute for Materials Research and Testing (BAM), Department 9.3 "Welding Manufacturing Processes", Berlin, and funded by the Federal Ministry of Economics and Technology via the AiF as part of the programme for the promotion of joint industrial research and development (IGF) on the basis of a resolution of the German Bundestag. Authors: M. Rethmeier, S. Gook, A. Gumenyuk Publication: 2013

P 823 - Further development of an optimised corrosion-protected system for low-alloy structural steel with a thermally sprayed protective coating based on modified zinc alloys as a supplement to batch galvanising of components Thermal spraying is an alternative process for the cathodic corrosion protection of steel structures that cannot be batch galvanised. In this research project, new thermally sprayed coating materials based on ZnCr, ZnSnAl and ZnMgAl were developed as a supplement to hot-dip galvanised coatings, with the latter alloy exhibiting corrosion protection properties that are better than those of ZnAl15 (currently frequently used). The developed coatings and relevant reference materials were first subjected to a basic characterisation to determine porosity, microhardness, chemical composition and adhesion strength. Electrochemical corrosion tests, the salt spray test and the VDA alternating test were carried out to evaluate the corrosion resistance of the analysed systems. The electrochemical corrosion tests showed that the corrosion rates of ZnMgAl and ZnAl15 are the lowest. In the salt spray test, sheets without an organic coating and with two organic top coats were exposed for up to 2,448 h and then analysed macro/microscopically. With an organic coating, no metallic coating system showed any failure during the test period. In the salt spray tests without organic coating, the ZnMgAl alloy showed the least corrosive attack. A chemical analysis of the corrosion products formed showed analogies to strip-galvanised ZnMgAl alloys. In the VDA alternating test, the thermally sprayed systems with a low Al content had the lowest corrosion infiltration on an artificially introduced crack. Parallel to the corrosion tests, the sustainability of the coating systems under consideration was evaluated, with a cost comparison also being carried out in order to assess the potential of the respective technologies (hot-dip galvanising / thermal spraying) and materials used. If a service life of more than 40 years is aimed for, then the coating systems with TS layers of ZnAl15 and ZnMgAl represent the most sustainable solutions for corrosion protection in the overall assessment. A 2-year outdoor weathering of selected coating systems since June 2012 is intended to substantiate the findings from the laboratory tests carried out. The IGF project 16434 N of FOSTA -Forschungsvereinigung Stahlanwendung e.V., Düsseldorf, was funded via the AiF as part of the programme for the promotion of joint industrial research and development (IGF) by the Federal Ministry of Economics and Technology on the basis of a resolution of the German Bundestag. The project was carried out at the Chair of Surface Technology in Mechanical Engineering, RWTH Aachen University, at the Institute of Ferrous Metallurgy, RWTH Aachen University, and at the Institute and Chair of Steel Construction and Light Metal Construction, RWTH Aachen University. Authors: K. Bobzin, C. Schulz, W. Bleck, T. Ingendahl, M. Feldmann, C. Heinemeyer Publication: 2013

P 827 - Development of a Eurocode-based design concept for bonded joints in steel construction (based on DIN EN 1990) Despite the many advantages of adhesive bonding as a joining method, this technology has not yet been able to establish itself in the construction industry in general and in steel construction in particular. The reason for this is that structural engineers, architects and building owners have doubts about the verifiability, durability and load-bearing capacity of bonded steel structures. In order to make this innovative bonding technology usable in the construction industry, it is necessary to process bonded joints in a standardised manner. The aim of the research project is to develop design concepts for bonded joints in steel façade construction. Publication: 2013 Authors: Prof Dilger, Prof Pasternak

P 828 - Robustness and reliability of calculation methods of bonded joints with high-strength steel sheets under crash conditions The previous project "Development of methods for the calculation of high-strength steel adhesive joints in vehicle construction under crash load" (P676) was completed in spring 2007. The work carried out is used in industrial applications as a basis for the crash calculation of vehicle (part) models and components. A total of five material models for adhesives and adhesive layers emerged from the project. It was not possible to select a model to be favoured on the basis of the project results at that time. The question of the robustness of the methods and the reliability of the predictions also remained unanswered. The current project addressed these issues. The models focussed on two fundamentally different approaches and their further development. The experiments were extended in their range of load cases and load velocities compared to the previous project and their measurement technology was improved. Both the measurement uncertainty and the scatter of the results were analysed. This information was included in the parameter identification in order to determine the reliability and sensitivity of the parameters. The effect of the uncertainty of the parameters was in turn analysed in the simulations of the validation tests. Overall, this provided a picture of the accuracy of the advanced modelling and parameter identification methods. Furthermore, the analyses show for which experiments a reduction of the scattering would particularly contribute to increasing the predictive accuracy of the models and to what extent the experimental database suggests a model reduction. The choice of experiments for parameter identification had at least as great an influence as the scattering of the experiments, for example the use of the tensile shear or compressive shear test to characterise the shear behaviour. Various validation tests were simulated with several parameter sets, from which the tests for parameter identification were determined which led to the best agreement with the experiments. However, it could not be conclusively clarified why not all tests can be simulated equally well with one parameter set. Therefore, the differences between simulations with different parameter sets are to be understood as the current uncertainty of the crash simulation of bonded structures. On average, agreement between tests and simulations was achieved to within 20 %. Publication: 2016 Authors: Dr M Brede, Dr.-Ing. O. Hesebeck, Dr.-Ing. St. Marzi, Dipl.-Math. Techn. N. Nörenberg, Dr. M. May, Dipl.-Ing. S. Kilchert, M.Sc. H. Voß, Prof. Dr.-Ing. A. Matzenmiller, Dr.-Ing. F. Burbulla, Dr. D. Memhard, Dr. W. Böhme, M.Sc. J. Lienhard, Dipl.-Ing. (FH) C. Fehrenbach