Papers by Keyword: Steel Sheet

Abstract: Straightforward and reverse descriptions are used to describe the metal’s plasticity zone. For the straightforward descriptions of the hardening zone, the “reference” point is the relative deformation ε_y corresponding to the yield strength σ_y. The deviation of the relative deformations in the metal hardening zone is measured relative to ε_y, and the deviation of the normal stresses is measured relative to σ_y. For the reverse descriptions of the metal hardening zone, the “reference” point is the relative deformation ε_u corresponding to the ultimate strength σ_u. The deviation of the relative deformations in the metal hardening zone is measured relative to ε_u, and the deviation of the normal stresses is measured relative to σ_u.

Abstract: The cutting surface obtained through the blanking process is often characterized by localized plastic deformations followed by crack propagation and ductile failure. The resulting blanked edge is essentially characterized by known areas such as shear zone, fracture zone and also sometimes burr. Their formation depends essentially on various process parameters and cutting material such as punch/die set, punch speed and temperature. The present study was carried out in order to investigate the possibilities for improving the quality of the cut-surface of high-alloy thick sheet steel. It was focused on modeling and analyzing blanking process of steel sheet using finite element method (FEM). The numerical results of the validation simulations were in agreement with the experimental results, thus validating the model parameters used. The model was developed in order to study the effects of process parameters on the blanking of mechanical steel parts, with particular attention to the study of punch-die gap influence.

Abstract: If resistance spot welding (RSW) is conducted when there is a gap between a steel sheet and an unmovable electrode, the steel sheets are bended by a movable electrode, and the quality of RSW is influenced. Therefore, it is necessary to understand the effect of the gap on RSW. In this study, two high-tensile strength steel sheets were welded with the gap. In addition, cross-section observations and cross tension tests were conducted to verify the effect of the gap on weldability and joint strength. Consequently, two notable results were obtained. First, the observation indicated that deformation around the corona-bond was varied depending on the gap. Second, the cross tension tests showed that the gap decreased the joint strength even though the nugget was large enough. These result indicated that controlling the gap is important to ensure the quality of RSW.

Abstract: In order to promote the efficient use of composite materials in civil engineering infrastructure, effort is being directed at the development of design criteria for composite structures. Insofar as design with regard to behavior is concerned, it is well known that a key step is to investigate the influence of geometric differences on the non-linear behavior of the panels. One possible approach is to use the validated numerical model based on the non-linear finite element analysis (FEA). The validation of the composite panel’s element using Trim-deck and Span-deck steel sheets under axial load shows that the present results have very good agreement with experimental references. The developed finite element (FE) models are found to reasonably simulate load-displacement response, stress condition, giving percentage of differences below than 15% compared to the experimental values. Trim-deck design provides better axial resistance than Span-deck. More concrete in between due to larger area of contact is the factor that contributes to its resistance.

Abstract: The paper presents results of quality analysis of the welded joints realized by CO2 laser (AF8P) using automotive body sheets and sheets for car chassis. There were used double-sided galvanized steel sheets of different grades and thicknesses. Welded joints were evaluated visually and then carrying capacity of the joints was established using tensile test. Welded joints were tested by following destructive tests: microhardness, macro and microstructure of the joints on metallographic sections using light microscopy. Results showed that the welding parameters were chosen appropriately.

Abstract: Resistance spot welding has been widely used in sheet fabrication for several decades. Development of new materials leads to innovation of welding processes. The paper describes the principle of innovative welding method known as Delta Spot and evaluates the properties of Delta Spot joints made by combination of galvanized steel sheets H220PD (a₀ = 0.9 mm) and TRIP 40/70+Z100MBO (a₀ = 0.77 mm). The quality of welded joints was evaluated by tensile test and metallographic analysis. The influence of the welding parameters on the structure of welded joint was observed too. The properties of Delta Spot joint were compared to the properties of standard resistance spot welds.

Abstract: Numerous investigations have been performed in an attempt to improve fatigue strength of materials by creating compressive residual stresses in the surface layers as a result of the shot peening process. For example, during exploitation of the separating screener, some parts of screen sieve plate situated near the fixed edge undergo the largest deformation caused by impact bending and need special treatment. In this paper, the results of experimental tests are presented to analyse the effect of micro shot peening on surface layer characteristics and fatigue strength of steel sheet specimens. The effect of shot peening is more visible when fatigue life is taking into account. Thus, the use of shot peening of sheet surface made it possible to increase fatigue life of screener sieve.

Abstract: The article deals with analysis of thin steel sheets formability. The aim is to verify possibilities of formability of metal sheet with thickness 0.85 mm according to material properties reached from experimental tests by numerical simulation. Simulation has been realized on two models with analysis of resulting data. Reached values can be used during simulation of real forming process.

Abstract: A fully automated laboratory-scale workstation has been constructed for simulating industrial acid pickling processes of steel sheet products. The device built comprises 4 liquid tanks that can be heated up to 80 °C and an arbitrary immersion program can be performed with the sheets to be tested by varying the immersion time and the motion velocity in each tank. The weight loss has been measured for both hot-rolled and cold-rolled specimens as a function of all variable parameters. The weight loss associated with the removal of the oxide layer could be established. The average oxide-related loss was 58 g⋅m^-2 and 2 g⋅m^-2 for hot-rolled and cold-rolled samples, respectively. It was found that the immersion time is the decisive parameter in the weigh loss measured, while the motion velocity and the temperature of the sample treatment are of secondary importance.

Abstract: In general, the magnetic properties of electrical steel sheets are strongly influenced by mechanical stress. We have reported the measurement results of vector magnetic properties of a non-oriented electrical steel sheet under stress conditions. From these results, it is possible to control the vector magnetic property by applying local mechanical stress. Therefore, we next focus on an induction heating technique that applies mechanical stress in a non-oriented electrical steel sheet. It is very important to control the eddy current distribution inside the non-oriented electrical steel sheet. This paper presents a magnetic flux concentration plate structure to control the eddy current in steel sheets by using an induction heating technique. The magnetic flux concentration plate structure is investigated in a three-dimensional magnetic field analysis by the finite element method.