Modifcication of selected high strength cast steels by a low amount of Titanium

The article deals with two middle alloyed high strength cast steels and the possibility of their mechanical properties improvement with modification by titanium. The presented study has two main topics. The former is the evaluation of basic mechanical properties of modified and unmodified samples in normalizing and quenched-and-tempered states. The latter is the effect of modification exhibited on the nitridation process and parameters evaluated after nitridation as the course of micro hardness across nitridation layer, the depth of the layer and hardness of nitride surface

Microstructure investigation of cast irons with nodular and flake graphite via nanoindentation

The paper investigates and compares the local mechanical properties of microstructure components in grey iron EN GJL -300 and ductile iron EN GJS -500-7. The microstructure of both cast irons is analysed by LOM, and then certain microstructure components found and their local mechanical properties are investigated. Finally, the resulting nanohardness and reduced Young modulus of the components are discussed and compared between the two cast irons used. A Hysitron TI -950 gauge with Triboscan software is used to perform experiment measurements

Comparison of the nanoindentation results of two generation of powder metalurgy produced materials for plastic industry

This article analyses the properties and nanoindentation characteristics of the stainless PM steels M390 Microclean® and M398 Microcelan®. In a first part, the literature sources on PM steels, stainless steels and thermochemical treatment were studied in order to collect information on the problems that can be found in the thermal or thermochemical treatment of M390 and M398 to improve their mechanical and anticorrosion properties. Optical microscopy of both materials is presented to show the structure and get a more complex picture about them. The main reason for this article – the nanoindentation was performed on the Hysitron Triboindenter TI 950. For both samples, 7 indentation points were selected on the SPM scan – 4 for carbides and 3 for the base matrix. Based on the results, the nanohardness H and the reduced modulus of elasticity Er as well as the reduced modulus of elasticity of the phases ES were determined. The nanohardness H of the matrix corresponds to that of the ferrite, which confirms the material manufacturer\u27s specifications. The nanohardness of the carbides corresponds to the results of the other materials tested by CEDITEK

Application of Carbon–Flax Hybrid Composite in High Performance Electric Personal Watercraft

Within the herein presented research, we studied the applicability of flax fabrics for composite parts in personal watercrafts in order to enhance damping of vibrations from the engine and noise reduction (which is relatively high for contemporary carbon constructions). Since the composite parts are intended to be exposed to humid environments requiring high levels of mechanical properties, a carbon–flax composite was selected. Samples of carbon, fiberglass, flax, and hybrid carbon–flax twill and biax fabrics were subjected to tensile and three-point bending tests. The mechanical properties were also tested after exposure of the samples to a humid environment. Damping was assessed by vibration and noise measurements directly on the complete float for samples as well as real parts. The hybrid carbon–flax material exhibited lower values of tensile strength than the carbon material (760 MPa compared to 463 MPa), but, at the same time, significantly higher than the other tested materials, or flax itself (115 MPa for a twill fabric). A similar trend in the results was observed for the three-point bending tests. Vibration tests and noise measurements showed reductions in vibration amplitude and frequency when using the carbon–flax hybrid material; the frequency response function for the watercraft part assembled from the hybrid material was 50% lower than for that made of carbon. Testing of samples located in a humid environment showed the necessity of surface treatment to prevent moisture absorption (mechanical properties were reduced at minimum by 28%). The tests confirmed that the hybrid material is satisfactory in terms of strength and its contribution to noise and vibration damping

Change in Dimensions and Surface Roughness of 42CrMo4 Steel after Nitridation in Plasma and Gas

The influence of plasma nitriding and gas nitriding processes on the change of surface roughness and dimensional accuracy of 42CrMo4 steel was investigated in this paper. Both processes almost always led to changes in the surface texture. After plasma nitriding, clusters of nitride ions were formed on the surface of steel, while gas nitriding very often led to the new creation of a formation of a “plate-like” surface texture. In both cases of these processes, a compound layer in specific thickness was formed, although the parameters of the processes were chosen with the aim of suppressing it. After the optimizing of nitriding parameters during nitriding processes, it was found that there were no changes in the surface roughness evaluated using the Ra parameter. However, it turned out that when using a multi-parameter evaluation of roughness (the parameters Rz, Rsk and Rku were used), there were presented some changes in roughness due to nitriding processes, which affect the functional behavior of the components. Roughness changes were also detected by evaluating surface roughness profiles, where nitriding led to changes in peak heights and valley depths. Nitriding processes further led to changes in dimensions in the form of an increase of 0.032 mm on average. However, the magnitude of the change has some context on chemical composition of material. A larger increase in dimensions was found with gas nitriding. The change in the degree of IT accuracy is closely related to the change in dimension. For both processes, there was a change of one degree of IT accuracy compared to the ground part (from IT8 to IT9). On the basis of the achieved dimensional accuracy results, a coefficient of change in the degree of accuracy IT was created, which can be used to predict changes in the dimensional accuracy of ground surfaces after nitriding processes in degrees of accuracy IT3–IT10. In this study, a tool for predicting changes in degrees of accuracy of ground parts after nitriding processes is presented

Hot Deformation Process Analysis and Modelling of X153CrMoV12 Steel

Analysis of the high temperature plastic behavior of high-strength steel X153CrMoV12 was developed in the temperature range of 800–1200 °C and the deformation rate in the range of 0.001–10 s−1 to the maximum value of the true strain 0.9%. Microstructural changes were observed using light optical microscopy (LOM) as well as atomic force microscopy (AFM). The effect of hot deformation temperature on true stress, peak stress and true strain was evaluated from the respective flow curves. Based on these results, steel transformation was discussed from the dynamic recovery and recrystallization point of view. Furthermore, a present model, taking into account the Zener–Hollomon parameter, was developed to predict the true stress and strain over a wide range of temperatures and strain rates. Using constitutive equations, material parameters and activation energy were derived, which can be subsequently applied to other models related to hot deformation behavior of selected tool steels. The experimental data were compassed to the ones obtained by the predictive model with the correlation coefficient R = 0.98267. These results demonstrate an appropriate applicability of the model for experimental materials in hot deformation applications

Analysis of the wear on machined groove profiles using reverse engineering technology

One of the key components in making Industry 4.0 a reality includes machines that are able to produce re-quired products and components faster, more precisely and more flexibly than ever before based on so-called reverse engineering technology. Reverse engineering is a technology which enables rapid acquisition of data for CAD, CAM, CAE, thereby greatly shortening the development, design and fabrication of parts. In general, analog data is converted to digital data, which is further processed. The paper deals with the analysis of prototype models of disc milling cutters with different blade profiles. The inspection of the shape of the disc-type prototypes is based on the reading of the digitized reference CAD model (workpiece with machined grooves), the subsequent positioning of the digitized protrusions of the disc mill cutters (milling cutter with edge profile 1, milling cutter with edge profile 8) with respect to this reference CAD model, creating a colour map of the deviations at the selected points. The aim of the paper was to analyse the resulting wear (deviation of the dimensions at selected points) on the prototype of the disc milling cutters with the profiles of the blades 1 and 8, which was simplified on the workpiece with the machined profiles of the grooves 1 to 4. © 2021 Manufacturing Technology. All Rights Reserved.European Regional Development Fund, ERD