18 und 19 February 2025
25. Kolloquium: Gemeinsame Forschung in der Klebtechnik

The colloquium "Joint Research in Adhesive Bonding Technology" has been the forum for adhesive developers, manufacturers and users for many years. Overview lectures from the industry, presentations by adhesive manufacturers and lectures on joint industrial research projects provide a comprehensive picture of the current state of research and application.

The Joint Committee Adhesive Bonding Technology, consisting of the four AiF research associations DECHEMA, DVS, FOSTA and iVTH, and its co-operation partners have been offering scientists, developers, manufacturers and users the opportunity to gain an overview of current research and to enter into dialogue with each other for over 20 years with this colloquium.

Venue:
Maternushaus Köln
Kardinal-Frings-Str. 1-3
50668 Köln

Detailed information on the colloquium can be found on the following website.

13 February 2025

The results of the research project ‘Innovation and safety through the use of duplex steels in road tunnels’ will be presented and discussed at the information day, which brings together all those involved in the tunnelling process and invites them to exchange ideas.

Venue:
Stahl-Zentrum
Sohnstraße 65
40237 Düsseldorf

Click here for the registration form.

27 March 2025
IGF Congress

As part of the IGF Congress, the Federal Ministry of Economic Affairs and Climate Action will present a special award for outstanding research projects in the IGF. Three nominated projects will be presented in the form of videos at the congress. The audience will then decide on the best project on site. The winners will receive professional public relations support, including an exclusive short video and valuable press relations measures.

P 1282 – Application of arc brazing for joining of attachment parts on cyclic high stressed steel structures (IGF-No 29 EWBG)

The project investigated arc brazing as an alternative to conventional welding for secondary attachments on dynamically loaded structures, aiming to reduce notch effects without requiring post-weld treatment. The copper-based alloy CuAl7 was selected for further study based on its suitability and cost. The brazing alloys demonstrated good mechanical properties, even for heavy plate joints, with no negative impact on mechanical-technological properties despite the occurrence of Liquid Metal Penetration (LMPs) in diffusion zones. The study formulated best-practice conditions and preliminary brazing process specifications (pBPS). Fatigue strength tests showed that brazed joints exhibited higher fatigue strength than welded joints, with failure characteristics similar to welded details. No influence of plate thickness on fatigue strength was found, and brazed plates with larger diameters showed no significant difference in fatigue performance. Economic analysis demonstrated that arc brazing is more cost-effective than welding with post-weld treatment, as it eliminates the need for additional labor-intensive post-processing. more information

P 1310 – Corrosion mechanisms during laser welding of compound steels (IGF-No 20721 BR)

The research aimed to produce high-quality filigree structures from duplex steel using laser beam welding without filler metal or solution annealing. The focus was on material 1.4462 (cold-rolled) with plate thicknesses up to 2 mm. Initially, single-beam processes were studied, including the effects of optical setups, multi-component gas mixtures, and pulse modulation. A simulation model was developed alongside experiments to analyze the welding processes. Based on its results, in-situ post-heating was implemented using a two-beam setup with fixed and scanner optics. Achieving the required 30% austenite content in the weld metal was not possible.
After optimizing the welding and post-treatment processes, corrosion resistance was analyzed using various methods. A new micro-electrochemical cell was developed to measure properties in the micrometer range. Tests with ferric chloride (ASTM G48) and 3% NaCl showed high pitting corrosion resistance and a correlation between chemical and electrochemical results. The two-beam strategy minimized weld spatter and defects, meeting DIN EN ISO 13919-1:2020-03 requirements.
more information

P 1311 – Appropriate repair of weld seams during manufacturing of high-strength fine-grain structural steel components (IGF-Nr. 20162 N)

During steel structure assembly, unacceptable irregularities in welding can occur despite adherence to specifications. Current guidelines recommend local thermal gouging and re-welding but offer limited information on optimal repair methods, particularly regarding welding-induced stresses and microstructural degradation. This issue is more pronounced with high-strength steels, leading to reduced mechanical properties and recurring defects. To address this, systematic investigations were conducted on welding stresses and microstructural changes in repair welds, focusing on shrinkage restraints, heat control, and repair cycles. The study identified factors that reduce stresses and prevent microstructural degradation and repeat defects, with adaptive heat control proving effective. Based on these findings, repair recommendations were made for high-strength steels like S500MLO (offshore) and S960QL (mobile cranes). These results contribute to more efficient designs for wind turbines and other high-strength structures, offering a foundation for developing standards that minimize rework and improve the use of high-strength steels, benefiting SMEs and supporting Germany’s energy transition.
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P 1320 – Preparation of a test specification for the inplane torsion test (IGF-No 21137 N)

The research aimed to develop a test specification for the in-plane torsion test by investigating various influences on test results. Machine-side factors such as the torque sensor, optical strain measurement, and height differences between inner and outer clamping, as well as clamping geometry and structuring effects on slipping and wrinkling limits, were analyzed. These insights informed a design guideline to adapt the testing machine to specific materials.
Specimen-side factors revealed that the grooved specimen shape impacts strain inhomogeneity through the sheet thickness. A suitable specimen shape for flow curve determination was derived. While fracture strain depends on the specimen manufacturing process, surface quality is not the sole factor affecting strain increases.
Ensuring quasi-static testing posed a challenge, addressed by developing an analytical model to define maximum strain rates and rotational speed guidelines based on material properties. A reproducible test sequence for flow curve determination was established and validated through comparative tests. Economic analysis confirmed the in-plane torsion test as a cost-effective alternative. A finalized test specification was proposed for reliable flow curve determination.
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P 1385 – Yield-controlled tightening of bolted connections M12 to M72 for steel construction (IGF-Nr. 20838 N)

Preloaded bolted connections in steel construction are regulated by DIN EN 1090-2, the National Annex DIN EN 1993-1-8/NA, and DASt-Guideline 024. These standards specify process-safe tightening methods, such as the modified torque and combined methods, used in Germany. However, the yield-controlled tightening method, common in mechanical engineering, is not yet permitted in steel construction or wind turbine assembly due to insufficient practical studies and open questions regarding HV-bolting assemblies. This method enables high preloads with optimal utilization of bolting assemblies without overstressing.
This research investigated the yield-controlled tightening method for bolted connections (M12–M72) in steel construction. The goal was to establish normative foundations and validate the structural integrity of HV-bolting assemblies tightened to yield strength. Extensive tests, including single/multiple tightening, ultimate load, and fatigue tests, demonstrated that high and reliable preloads could be achieved. The results support normative recommendations for future use of this method in steel construction.
more information

P 1408 – Experimental investigation of the wind pressure distribution on open-topped and closed circular cylindrical silos and tanks (IGF-No 21602)

Silos and tanks with circular cross-sections are widely used for storing bulk materials and liquids. While filled, the symmetrical load creates uniform tensile stress, allowing thin-walled steel designs. However, in empty or partially filled states, asymmetrical wind loads can cause stability failure, making wind often the critical load case. The Eurocode's wind pressure models inadequately address certain design situations, particularly for silo groups.
This research involved wind tunnel tests on cylindrical silos and tanks with various H/D (height/diameter) ratios. For isolated silos (H/D = 0.3–4.0), results showed increasing suction loads with slenderness, peaking at around 70% of the height. For slender silos (H/D ≥ 1), the internal negative pressure reached Cpi ≈ -0.8, exceeding the Eurocode's -0.6.
Tests on silo groups with varied inflow direction (β) and spacing (S/D) revealed higher positive pressures on windward sides with decreasing S/D, especially on central cylinders. Slender models (H/D = 2.0) experienced increased lateral suction on upstream cylinders at β = 120°–135° and S/D = 0.1–0.25. These findings led to improved design recommendations and a refined wind load model for individual and grouped silos.
more information

P 1410 – Extension of DIN EN 1993-1-10 to offshore conditions for notch cases on hollow section joints for jacket construction (IGF-No 20832 N)

Jacket structures in offshore applications lack standardized rules for material selection and toughness requirements. This project aims to transfer the toughness verification concept from civil engineering to offshore jacket structures. Using fracture mechanics, a reference geometry is identified, crack assumptions are made, and crack propagation is calculated based on the load collective. This leads to a limit state analysis, from which toughness requirements are derived, considering strain rate, cold forming, and offshore conditions. The fracture mechanics approach, established in building and bridge construction, is successfully applied to jacket structures. Additionally, a novel methodology using a damage mechanics model is developed to determine toughness requirements for specific applications. The Modified Bai-Wierzbicki model, capable of simulating plasticity, ductile damage, and brittle failure under varying stress states, strain rates, and temperatures, is applied. Both approaches yield comparable results, with damage mechanics confirming the conservative nature of fracture mechanics.
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P 1415 – Innovative load capacity analysis of welded steel components using damage mechanics (IGF-No 20815 N)

This project investigated the load-bearing behavior of welded joints, especially with high-strength steels, using experimental and damage-mechanical simulations. A methodology was developed to derive damage-mechanical parameters for the heat-affected zone and weld metal, and an approach to account for mesh size dependence was implemented in commercial FE software. The models were validated through experimental tests on laboratory and component scales. Numerical studies on geometric and material influences on load-bearing behavior were also conducted. The results showed that the impact of softening zones in the heat-affected zone and undermatching on ultimate loads is less significant than expected, as high strains induce hardening in soft zones. Design rules for welded joints were reviewed, uncovering optimization potential. A weighted approach to tensile strength for undermatching joints improved the design rules. The findings support the use of high-strength steels, benefiting SMEs and strengthening Germany's position in steel construction.
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P 1418 – Profile straightening by partial rolling during roll forming (IGF-No 20960 N)

As part of the project 20960 N, a novel method for straightening defective profiles in roll forming is being developed. The goal is to understand the relationship between longitudinal strain distribution and profile defects and implement partial rolling of selected cross-sectional areas to correct these defects.
In the first phase, factors affecting profile defects and longitudinal strains during roll forming are identified. The second phase involves preparing numerical models and conducting experimental preliminary investigations, such as material characterizations. The third phase focuses on numerical studies of U-profiles and top-hat profiles to analyze strain curves and test partial rolling. An asymmetric geometry is used to study the superposition of vertical and horizontal bending and torsion.
Parallel experimental investigations validate the numerical models. Partial rolling is applied first to U-profiles and then to top-hat profiles, effectively eliminating profile defects. An analytical model for strain distribution based on defects is developed and validated using simulation results.
In the final step, the method is adapted for industrial profiles. Experiments with a complex partner profile confirm its effectiveness for correcting defects in intricate geometries.
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P 1438 – Development and testing of a model frame for the predictive elucidation of erosive wear in pneumatic conveyors (IGF-No 20815 N)

In this research project, wear in pneumatic conveyors was studied through both numerical and experimental methods at microscopic (particle impact) and macroscopic (pipe wear) scales. Four steel types (three stainless steels and one carbon steel) and a plastic were tested for wear resistance against rounded and angular bulk particles in various conditions. The study revealed the significant impact of particle shape on erosive wear. Detailed numerical simulations using SPH confirmed this relevance. Based on these results, an erosion model was extended with two parameters to describe particle shape, enabling rapid wear predictions and integration into CFD-DEM simulations for process analysis. Experiments were conducted to characterize particle contacts for CFD-DEM simulations. Validation simulations showed high agreement with experimental data, allowing for variation of system parameters (e.g., speeds, mass loads, and pipe geometries). This demonstrated that wear rates can be significantly reduced without disproportionately increasing pressure loss, depending on the application.
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The research projects were funded by the Federal Ministry of Economic Affairs and Climate Action as part of the "Industrial Collective Research" programme on the basis of a resolution of the German Bundestag and by the Foundation for Steel Application.