https://popups.uliege.be/esaform21/index.php?id=79 Coordinator: Prof. Bernd-Arno Behrens Co-Organiser: Prof. Wolfram Volk, Prof. Alexander Brosius, Prof. Hinnerk Hagenah (tbc) Description: Topics covered by this minisymposium include but are not limited to: Development of new and optimization of existing forming and rolling processes; Mathematical description and parameterisation of flow, damage and fracture behaviour of new workpiece and tool materials; Mathematical description and parameterisation of friction, heat transfer and wear in forging and rolling; Development of numerical methods, formulations and algorithms for simulation of forging and rolling processes; Validation of simulation models on industrial examples; Computer-aided process control. Furthermore, the results of the Collaborative Research Center 1153 on Tailored Forming are presented. Mini Symposia fr Wed, 03 Mar 2021 09:33:41 +0100 Wed, 14 Apr 2021 09:53:22 +0200 https://popups.uliege.be/esaform21/index.php?id=79 0 https://popups.uliege.be/esaform21/index.php?id=574 Multi-material solutions offer benefits, as they, in contrary to conventional monolithic parts, are customised hybrid components with properties that optimally fit the application locally. Adapted components offer the possibility to use high strength material in areas where external loads require it and substitute them by lightweight material in the other areas. The presented study describes the manufacturing of a hybrid shaft along the process chain Tailored Forming, which uses serial pre-joined semi-finished products in the forming stage. Subject of this study is the numerical modelling of the heating process by induction heating of a hybrid semi-finished product and the resulting material distribution after the impact extrusion process. For this endeavour, a numerical model of an inhomogeneous induction heating process was developed. The main challenge is to determine the boundary conditions such as current intensity acting in the induction coil and the electromagnetic properties of the used material. The current intensity was measured by a Rogowski coil during experimental heating tests. The relative magnetic permeability was modelled as a function of temperature using the method of Zedler. The results show the importance of using a relative magnetic permeability as a function of temperature to guarantee a high quality of the numerical model. Subsequently, the model was applied to the heating of the hybrid semi-finished product consisting of a steel and aluminium alloy. By using inductive heating and thus a resulting inhomogeneous temperature field, good agreement of the material distribution between experiment and simulation could be achieved after the forming process. Sat, 20 Mar 2021 12:20:49 +0100 https://popups.uliege.be/esaform21/index.php?id=574 https://popups.uliege.be/esaform21/index.php?id=896 The use of high nickel content austenitic stainless steels (SASS) has significantly increased in the last decade. The corrosion and high fatigue resistance of these materials make them suitable for manufacturing oil country tubular goods (OCTG). SASS are processing by forging from casting conditions. Dynamic recovery (DRV) and recrystallization (DRX) of as-cast super austenitic stainless steel, N08028 Alloy, is investigated to study the refining effect from the as-cast grain structure to fully recrystallized austenite due to hot deformation. Both the critical stress and strain for the initiation of DRX are determined using the flow curves. To perform this analysis, hot compression tests are performed at temperatures between 900°C and 1250°C, and strain rates between 0.1 s-1 and 10 s-1, up to 0,8 final strain using a Gleeble®3800 thermomechanical simulator. Subsequently, the Johnson-Avrami-Mehl-Kolmogorow (JMAK) model is used to numerically fit the flow curves and consequently determine the critical strain. No critical points are seen for temperatures under 1100°C. Above this temperature, the JMAK model proves to be valid in all studied strain rates. Mon, 22 Mar 2021 09:55:48 +0100 https://popups.uliege.be/esaform21/index.php?id=896 https://popups.uliege.be/esaform21/index.php?id=919 Bulk metal components are often used in areas which are subjected to very high loads. For most technical components, a distinction between structural and functional areas can be made. These areas usually have very different loading profiles, sometimes with contradictory requirements. Nevertheless, nowadays almost only monomaterials are used for the production of bulk metal components. With increasing requirements towards more and more efficient products with lower weight, compact design and extended functionality, these materials are reaching their material-specific limits. A significant increase of product quality and economic efficiency can be expected exclusively with locally adapted properties by combining different materials within one component. In this regard, the focus of this contribution is the production of a hybrid pinion shaft made of the material combination steel (37CrS4) and aluminium (AW6082). The tool concept for extrusion of the hybrid preform, the simulation-based design of the forming process as well as the material characterisation are presented. With the help of the FE-simulation, different serially arranged semi-finished component geometries were investigated in order to minimise the occurring tensile stresses in the component during the extrusion process to prevent failure during forming. Mon, 22 Mar 2021 10:10:58 +0100 https://popups.uliege.be/esaform21/index.php?id=919 https://popups.uliege.be/esaform21/index.php?id=929 Manufacturing high value components involves complex and non-linear thermo-mechanical processes to obtain optimum combination of microstructure and mechanical properties required for the final part. Among these, the ingot-to-billet conversion process, involving forging operations of upsetting and cogging, are critical to refine the as-cast coarse, elongated, and dendritic microstructure. In this study, the first stage of the ingot-to-billet conversion process has been investigated in type 316 austenitic stainless steel, aiming to propose a novel methodology for the characterisation of the as-cast material behaviour. Hot upsetting tests were carried out on cylindrical samples taken out from an industrial-scale ingot. The resulted microstructures were analysed, using advanced image analysis method, for the fraction and distribution of the recrystallised grains, highlighting the strong dependency of recrystallisation behaviour on the initial microstructure of the as-cast material. Using a finite element (FE) model considering the anisotropic behaviour of the material, originated from the preferential grain growth during casting, the deformation of the samples were predicted with a good accuracy. The results demonstrate the importance of considering the anisotropic plastic properties in the FE models to effectively predict the as-cast material deformation, shape and thus the thermo-mechanical characteristics applied during forging. Mon, 22 Mar 2021 10:22:17 +0100 https://popups.uliege.be/esaform21/index.php?id=929 https://popups.uliege.be/esaform21/index.php?id=954 Multi-material solutions represent a promising approach for the production of load-optimised parts. The combination of material-specific advantages of different materials in a single component allows the fulfilment of conflicting requirements e.g. high performance and low weight. Fabrication of hybrid components is challenging due to the dissimilar properties of the individual materials and requires the development of suitable manufacturing technologies. The present paper deals with the simulation-based design of a forming process for the production of a suspension control arm consisting of steel and aluminium. With the focus on material flow, two forming concepts, open-die and closed-die forging, were investigated, in order to ensure the required material distribution similar to the final part. In addition, a tool analysis was carried out to avoid thermo-mechanical overload of the tool system. It was found that the required material distribution can be achieved with both forming concepts. However, a closed-die forging concept is not suitable because of the high stresses in the forging dies exceed the tool steel’s strength. Mon, 22 Mar 2021 10:30:37 +0100 https://popups.uliege.be/esaform21/index.php?id=954 https://popups.uliege.be/esaform21/index.php?id=1475 Nowadays, numerical simulations are more and more used in forging industry, and their predictability is validated through a comparison with experiments. But sometimes simulations and experiments provide significantly different results. And quite often, the models implemented in simulations are taken for responsible of this divergence with experimental results. But results experimentally obtained can also be discussed. Depending on the operatory conditions, and the type of sensor used, measured results can be different. Moreover, integrating sensors is not an easy task for forging processes, as sensors could be exposed to harsh environment with high speeds, high forces, high temperatures, radiations, … In this paper data for displacement and force measured by different sensors are compared. Advantages of different sensor technology are discussed in the case of hot forging processes performed with energy piloted machines. Mon, 22 Mar 2021 19:58:19 +0100 https://popups.uliege.be/esaform21/index.php?id=1475 https://popups.uliege.be/esaform21/index.php?id=1896 Hot rolling of bars issued from continuous-casting aims at refining the material structure and guaranteeing the central soundness of the metallurgical product. The rolling route must be designed to achieve the complete closure of the shrinkage porosity inherent in the continuous casting process. To predict the void evolution, many models exist that can be implemented in the finite element simulation of the process. Nevertheless, these models need parameter adjustments to be adapted to the forming process, the formed material, and the real geometry of the void. Real scale tests being very expensive in the long product rolling mill, an improved representativeness experimental configuration was designed to reproduce at the laboratory scale the key characteristics of the thermomechanical path driving the void closure phenomenon. This testing consists of successive forming stages with shaped anvils applied to samples containing a shrinkage cavity. The shaped anvils and the forming conditions are calibrated to reproduce the levels of strain and the stress triaxiality of rolling stands, and the alternation of the forming direction of the industrial process. The geometry of the voids before and after the forming paths are measured by tomography. The simulation of the test with an explicit modelling of the void is developed parallel to the experiments. The simulation/experiment comparison allows the validation of the numerical model. The obtained model will be used in future works to perform a more extended design of experiments to characterise void closure during hot rolling of bars. Tue, 23 Mar 2021 10:30:57 +0100 https://popups.uliege.be/esaform21/index.php?id=1896 https://popups.uliege.be/esaform21/index.php?id=2697 Due to high thermo-mechanical loads, tools used in hot forming operations need a high resistance to different damage phenomena, such as deformation, cracking and abrasion. They are exposed to cyclic thermo-mechanical stress conditions, which leads to tool failure and subsequent tool replacement during cost-intensive production interruptions. To increase wear resistance, forging tools can be produced in the metastable austenite area. Forming of steel below the recrystallisation temperature, also known as “ausforming”, offers the possibility to increase strength without affecting ductile properties. This is due to grain refinement during forming. In this study, the thermo-mechanical treatment ausforming will be used to form the final contour of forging dies. For this purpose, an analogy study was performed where a cup-preform is ausformed, which represents the inner contour of a highly mechanically loaded forging die. It is investigated to what extent a fine-grained microstructure generated in the last forming stage can be achieved and how it influences the tool’s performance. The hot-working tool steel X37CrMoV5-1 (AISI H11) was used as workpiece material. To achieve optimal properties, process routes with tempering temperatures from 300 °C to 500 °C and global true plastic strains of φ = 0.25 and φ = 0.45 were examined. The results were evaluated by pulsation tests, metallographic analysis and hardness measurements of the formed parts. Optimal ausforming parameters were derived to produce a high performance forging die. Wed, 24 Mar 2021 18:45:22 +0100 https://popups.uliege.be/esaform21/index.php?id=2697 https://popups.uliege.be/esaform21/index.php?id=2824 The research subjects of current investigations at the Institute for Metal Forming Technology (IFU) Stuttgart include the manufacture of face gearings. Usually, gearings are produced by means of a coining process, which causes high process forces that considerably restrict the geometry of the teeth in terms of the height-to-width ratio. In order to avoid these problems, a new forming process has been developed. This technology offers significant advantages, such as the reduction of process forces and the ability to manufacture the required tall and acuminate tooth elements through a cold-forming process. This paper describes the design and functionality of the novel pin-to-gear forming process. In this paper, the operating principle of the method is presented first of all. The new pin-to-gear process is then compared to conventional coining and the free-divided-flow (FDF) process developed at IFU Stuttgart in 2018. This examination takes the form of a numerical simulation using DEFORM-2D software. To investigate the influence of preform parameters on the form filling of the tooth cavities, parameter studies in design and geometry are conducted. Process limits regarding geometric constraints are presented alongside possibilities for increasing process reliability. Through this investigation, the potential and opportunities of the innovative pin-to-gear forming process will be illustrated. Wed, 24 Mar 2021 19:06:51 +0100 https://popups.uliege.be/esaform21/index.php?id=2824 https://popups.uliege.be/esaform21/index.php?id=3775 Energy prediction and starvation have become an essential part of process planning for the XXI century manufacturing industry due to cost-saving policies and environmental regulations. To this aim, the research presented in this paper details how machine learning-based algorithms can be an effective way to predict and minimize the energy consumptions in the widely spread radial-axial ring rolling (RARR) process. To analyze this bulk metal forming process, 380 numerical simulations have been developed using the commercial SW Simufact Forming 15 and considering three largely utilized materials, the 42CrMo4 steel, the IN 718 superalloy, and the AA6082 aluminum alloy. To create the database for both multi-variable regression and machine learning models, ring outer diameters ranging from 650 mm to 2000 mm and various process conditions including different sets of tool speeds and initial temperatures have been considered. For the case of the multi-variable regression model, to account for all the cross-influences between all the parameters, a second-order function including 26 parameters has been developed, resulting in a reasonable average accuracy (94 %) but also in an impractical huge equation. On the other hand, the machine learning model based on the Gradient Boosting (GB) approach allows obtaining a similar accuracy (96 %) but its compact form allows a more practical utilization and its training can be expanded almost indefinitely, by adding more results from both numerical simulations and experiments. The proposed approach allows to quickly and precisely predict the energy consumption in the RARR process and can be extended to other manufacturing processes. Mon, 29 Mar 2021 14:30:24 +0200 https://popups.uliege.be/esaform21/index.php?id=3775 https://popups.uliege.be/esaform21/index.php?id=3987 The four-roll rolling process (4RP) enables the further evolution of sizing processes in rolling mills for round sections. The well-known advantages of the three-roll process over the two-roll process can be further improved using the 4RP. The participation of four rolls in the deformation zone instead of three or two leads to a significant increase in deformation efficiency. The present work shows a pass design method for pass sequences in the four-roll rolling process. Here, three basic types of roll groove geometries are discussed: the flat groove, the non-opened single-radius groove, and a tangentially opened type of a single radius groove. Based on a predefined cross-sectional evolution, grooves are found numerically to satisfy two conditions, i.e., the cross section of the rolled section and the groove filling criterion. The equations of the equivalent pass method, together with a suitable model for lateral spread and the geometric equations of the groove are solved by nonlinear optimization to minimize the sectional and filling errors of a specific pass. Combined for several rolling passes, a complete pass design can be carried out for the reduction of a specified initial section to a final section. The presented results show, how a pass design method for the four-roll rolling process can be constructed. The newly developed model is implemented in a software solution for pass design and analysis of full section rolling mills. An exemplified pass design is discussed to show the possibilities and limitations of the new model. Tue, 30 Mar 2021 09:37:38 +0200 https://popups.uliege.be/esaform21/index.php?id=3987 https://popups.uliege.be/esaform21/index.php?id=4195 In the joint project PIREF, the metal forming group of the University of Duisburg-Essen has collaborated with the University of Applied Sciences Ruhr-West Mülheim (Ruhr), the University of Siegen, EMG Automation GmbH and SMS group GmbH to develop sensors, for an online measurement of material velocity and cross section as well as control models for the rolling process of wire rod and bars. The University of Duisburg-Essen provided a metal forming process model for the rolling process to assess the influencing parameters on the rolled section precision. A technique was found to segregate height- from width- influencing parameters from a measured cross-sectional area and actual roll gap. With this measuring technology and with help of the process model, rules for control of the rolling process to achieve close tolerances were obtained. The modelling was accompanied by rolling trials on a laboratory rolling mill at the University of Duisburg-Essen, where a typical Round-OvalRound pass sequence was used for validation of the rolling model concerning lateral spread, inlet and outlet velocity as well as rolling force and torque calculation. The present paper shows how the material flow and the distribution of the velocity in the roll gap can be described. In subsequent rolling of bar and rod in a continuous rolling mill the dimensions can be influenced by application of longitudinal stresses and screwdown. The application of stress can be achieved by an inter-stand velocity mismatch. With the developed models the necessary velocity mismatch can be calculated. Thu, 01 Apr 2021 15:29:33 +0200 https://popups.uliege.be/esaform21/index.php?id=4195