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Results 151 to 180 of 294:

Experimental Investigation of Armour (Armox-Aramid-UHMWPE)

Jindřich Viliš, Roman Vítek, Jan Zouhar, Michal Stejskal, Vlastimil Neumann

Manufacturing Technology 2023, 23(6):935-948 | DOI: 10.21062/mft.2023.083

In this study, the ballistic resistance of multi-layered composite armour is experimentally investigated. The composition of this armour consisted of armour steel Armox 500T, para-aramid fabric Twaron CT 747 and ultra-high molecular weight polyethylene Endumax Shield XF33. To compare the ballistic resistance, the ballistic resistance of the armour with the perforated steel Armox 500T was tested. The rifle cartridges 7.62 x 51 mm FMJ NATO M80 were used to test this resistance. The aim of this experiment was to compare the ballistic resistance of unperforated and perforated steel Armox 500T. As part of the experimental part, the chemical composition and microhardness of the steel Armox 500T was verified. The hardness of the composite materials was also measured for optimal armor configuration. After the projectile impact, the damage mechanism of the steel Armox 500T and the composite materials were investigated by using optical and electron microscopy. It was proved that the ballistic resistance of the perforated steel depends on the used pattern. Based on the performed experiments, the steel Armox with pattern A effectively reduced the weight of the testing configuration and absorbed all the kinetic energy of the projectile 7.62 mm FMJ M80.

Influence of Energy Ratio of Hybrid Heat Source on Residual Stress Distribution of 7A52 Aluminum Alloy VPPA-MIG Hybrid Welding

S.M. Gan, Y.Q. Han, X.Y. Bao

Manufacturing Technology 2022, 22(3):279-287 | DOI: 10.21062/mft.2022.033

Variable Polarity Plasma Arc-Metal Inert Gas (VPPA-MIG) welding process is a new hybrid welding process with broad application prospects for aluminum alloy structure in the fields of aerospace manufacturing, transportation and others. The heat source of the hybrid welding process is composed of VPPA heat source and MIG heat source. When the total input energy of VPPA-MIG hybrid heat source is constant, the different energy ratio of VPPA arc and MIG arc affects not only the forming effect of hybrid weld, but also the stress distribution of hybrid welding joint. Hole-drilling method was used to analyze the influence of the ratio of VPPA and MIG arc energy on the distribution of welding residual stress in the process of 10 mm 7A52 aluminum alloy VPPA-MIG hybrid welding. The results show that the peak magnitude of hybrid welding residual stress increases with the increase of the ratio of VPPA arc energy. Considering the appearance of weld forming, VPPA-MIG hybrid welding parameters of 7A52 aluminum alloy are optimized on the basis of the distribution characteristic of residual stress. When the ratio of VPPA arc energy is selected between 35% and 40%, the peak magnitude of transverse residual stress is (in the direction vertical to the weld) no more than 92.0 MPa, and the peak magnitude of longitudinal residual stress(in the direction parallel to the weld) is no more than 234.3 MPa. It shows that the VPPA-MIG hybrid welding with optimized parameters can not only produce weld joint with satisfied macroscopic appearance, but also avoid high peak magnitude of residual stress.

Characteristics of Pinewood Dust Combined with Vinyl Ester Composites Through Material Testing and Machining

Muhammad Wafiuddin Suhami, Norfariza Ab Wahab, H. Boejang, Khairum Hamzah, Hiroyuki Sasahara

Manufacturing Technology 2022, 22(5):590-597 | DOI: 10.21062/mft.2022.063

Natural fibre-reinforced polymer (NFRP) composites can be environmentally friendly and cost-effective alter-natives to synthetic fibre-reinforced composites. Major industries have expressed significant interest in the advancement of new natural fibre-reinforced composite materials. However, these materials perform poorly on their own and require further analysis since accessible information is lacking in the literature. This paper presents the results of previously reported works on natural fibre reinforced polymer composites, with strong attention to the types of fibres employed, the polymers used in the matrix, the treatment of fibres as well as the test parameters. The best proportion of composites is consequently selected. Composite materials are tested using a CNC router machine. Pinewood dust is combined with vinyl ester resin. A hand layup tech-nique is used to prepare the samples. The availability of relevant pinewood dust and the volume of pine wood dust to be used are first determined to continue with the experiment. According to the findings, the impact of machining performance is successfully evaluated by employing the tensile strength test, Charpy impact test, flexural strength test and surface roughness measurement. The findings are derived from the microscopic assessment of the surface roughness of pinewood dust (PWD) fibre reinforced vinyl ester resin.

Geometric Accuracy of Components Manufactured by SLS Technology Regarding the Orientation of the Model during 3D Printing

Miroslav Matuš, Vladimír Bechný, Richard Joch, Mário Drbúl, Jozef Holubják, Andrej Czán, Martin Novák, Michal Šajgalík

Manufacturing Technology 2023, 23(2):233-240 | DOI: 10.21062/mft.2023.027

Selective Laser Sintering (SLS) or sintering of polymer powders is one of the most well-known additive technologies for printing 3D components. The properties of individual polymer powder materials have a significant impact on the quality of the manufactured part. Potential deformation and shrinkage can occur during printing if a significant number of parts are piled on top of one another or are oriented incorrectly, accumulating thermal energy in certain areas. The aforementioned research focuses on an experimental study to investigate the impact of the distribution and orientation of printing samples in the build chamber on the accuracy of dimensions and the surface roughness of PA12 prints. The aim of the study was to examine the impact of model settings during production as well as the effect of individual factors on the properties of manufactured parts, with a focus on ensuring that heat rises evenly from each print without accumulating.

Machining of M390 Microclean® and M398 Mircoclean® PM Steels – the Comparison of Cutting Forces and Surface Roughness

Jozef Majerík, Juraj Majerský, Henrieta Chochlíková, Igor Barényi, Jana Escherová, Mária Kubasáková

Manufacturing Technology 2023, 23(6):853-860 | DOI: 10.21062/mft.2023.096

Article deals with comparison of cutting forces and surface roughness between materials produced by powder metallurgy M390 and M398 Microclean® from producer, company Böhler. Main interest is the analysis & comparison of the cutting forces and surface roughness after the processing by cutting in-serts with DNMG and WNMG geometry, radius 0.4 and 0.8 mm, after hard turning at the same pro-cess parameters for both materials and all types of cutting inserts. The comparative studies were car-ried out for cutting forces and surface roughness with the aiming to observe the difference between “old generation” M390 and “new generation” M398 PM Steel for future processing in production. The corelation between the cutting forces and surface roughness was investigated with resulting the M398 is necessary to process by higher cutting forces which are linked with higher surface roughness than at M390. It is in relation with higher contain of additive elements and carbides formed by them, even that the material is in delivered condition – soft annealed [1], [2]. These results helped to fulfil the knowledge about both materials in the row of experiments which are provided to increase material properties against abrasion and wear.

Surface Roughness, Topography, Accuracy, Chip Formation Analysis & Investigation of M390 and M398 Steels after Hard Machining

Jozef Majerík, Juraj Majerský, Igor Barényi, Henrieta Chochlíková, Jana Escherová, Mária Kubasáková

Manufacturing Technology 2023, 23(1):60-72 | DOI: 10.21062/mft.2023.015

Article deals with processing of intermetallic materials produced by powder metallurgy M390 and M398 Microclean® produced by Böhler. Main interest is the analysis & measurement of their surface rough-ness and topography after the processing by DNMG and WNMG geometry of cutting inserts with 0.4 and 0.8 mm radius after hard turning at the same process parameters for both materials and all types of cutting inserts. The comparative studies were carried out for the microgeometrical and chip formation research on the machined surfaces and the technological processes were assessed, including chip dia-grams. Spectral analysis was used to verify the composition of investigated materials by spectral analysis measuring device. In order to examine the surfaces in detail, in addition to the standard roughness measurement, surface topography was performed by the coherent correlation interferometric micro-scope. The results of surface roughness as well as topography show higher wear resistance of M398 ma-terial compared to M390. This was confirmed indirectly by the fact that it is primarily shown by the higher surface roughness of M398 after machining under the same conditions. These properties are ob-tained by a higher content of additive elements, respectively of their carbides. Based on the conclusions of these experiments, additional knowledge and recommendations for the processing of these materials were created.

Assembly Sequence Intelligent Planning based on Improved Particle Swarm Optimization Algorithm

Wei Zhang

Manufacturing Technology 2023, 23(4):557-563 | DOI: 10.21062/mft.2023.056

Traditional assembly sequence solving methods often face problems such as combinatorial explosion and low efficiency in solving complex products with multiple parts. To improve the level of assembly sequence planning (ASP), an interference matrix is established to express the basic assembly information of a product. Taking the stability of the assembly sequence, the number of assembly direction changes, and the number of assembly tool changes as evaluation indicators, a fitness function is constructed. An improved particle swarm optimization (IPSO) approach for ASP is developed based on the peculiarities of the ASP issue. Redefining particle positions, velocities, and their update operations, and introducing mutation operators in genetic algorithm (GA) to improve the ability of PSO algorithms to jump out of local optima. Furthermore, the algorithm's convergence speed is enhanced by adjusting the value of the inertia weight. Finally, an example is provided to demonstrate the IPSO algorithm's usefulness and efficiency.

Evaluation of the Corrosion Resistance of the Al-Si-Cu-Mg Alloy with the Addition of Zirconium

Marek Matejka, Dana Bolibruchová, Daniel Kajánek

Manufacturing Technology 2023, 23(6):861-869 | DOI: 10.21062/mft.2023.085

Aluminum alloys are one of the most used materials today, and therefore great emphasis is placed on their continuous development. Improving the ratio of strength and stiffness to weight, improving plasticity, casting properties or resistance to corrosion are examples of properties of aluminum alloys that are constantly being improved. This work focuses on the evaluation of the corrosion resistance of the Al-Si5Cu2Mg alloy with graded addition of zirconium (0.05; 0.10; 0.15; 0.20 wt.%). Corrosion re-sistance was evaluated based on immersion, exposure and potentiodynamic polarization tests. The addition of Zr to the AlSi5Cu2Mg alloy improved the thermodynamic stability in all evaluations. The application of heat treatment led to even more significant increases in corrosion resistance in almost all evaluations. Microscopic observation of the samples revealed mainly pitting corrosion along with intercrystalline corrosion.

Microscopic Wear Analysis of Indexable Inserts after Machining of 34CrNiMo6 Steel

Nataša Náprstková, Karel Šramhauser, Iryna Hren, Jan Novotný, Jan Sviantek

Manufacturing Technology 2023, 23(5):676-684 | DOI: 10.21062/mft.2023.077

Machining is an important part of the manufacturing process in the engineering field. Turning is one of these areas. At present, almost exclusively exchangeable cutting inserts are used in production machining. The article describes the research in the field of their wear, where the electron microscopy was used to evaluate the results. Electron microscopy is a very important aid in research in many are-as not only of human activity and also is the important aid in the field of mechanical engineering and manufacturing technologies. The results thus obtained can make in a given area it clearer and better document the resulting situation. Within the experiments, selected cutting inserts were used and the given material was machined. The electron microscope Tescan Vega 3, which is available at the workplace where the experiment was conducted, was used to evaluate the resulting wear. In the frame of experiments was also performed the composition analyze of used cutting inserts. Analyzes of the machined material were also performed to confirm the declarations from the supplier.

Head Impacts during the Direct Frontal (Forehead) and Side (Temple) Collision – Human vs. Hybrid III Dummy

Lubos Tomsovsky, Lucie Literova, Petr Kubovy, Frantisek Lopot, Martin Havlicek, Ondrej Stocek, Lukas Fara, Roman Jezdik, Hynek Purs, Tommi Tikkanen, Martin Novak, Karel Jelen

Manufacturing Technology 2023, 23(5):717-724 | DOI: 10.21062/mft.2023.048

The paper is focused on the dynamic response of a Hybrid III crash-test dummy during low-severity frontal (forehead) and side (temple) head impacts. The measurements used a pedestrian dummy (Hybrid III 50th percentile male dummy, Jasti Co., ltd., Tokyo, Japan) and a unique pendulum impact testing machine (impactor) of own design and construction. The tests were conducted at two various impact intensities (velocities) that did not exceed the speed of 1.6 m.s-1. The primary outcome variable was a resultant magnitude of acceleration measured on the vertex of the dummy’s head and the results were compared to 11 human volunteers. The goal of the study was to analyze the biofidelity of the Hybrid III Dummy in a pedestrian setting during low-severity frontal and side head impacts by comparing the dynamics and kinematics of the dummy’s head to human volunteers.

Design Modification of the Combi-type Body Considering the Impact on Vehicle Aerodynamics – Case Study

Michal Fabian, Róbert Huňady, Orlando Lagos

Manufacturing Technology 2023, 23(6):801-809 | DOI: 10.21062/mft.2023.099

Car manufacturers are constantly looking for new options to make the vehicle more attractive to the cus-tomer. In terms of design, this is usually done in the middle of a model's life cycle, when a so-called facelift of a production model is carried out. This involves small changes to the shape of the bodywork to improve the design of the vehicle until it is time for a new model range. This paper discusses a case study that focuses on the modification of the rear body components of a ŠKODA Superb III in Combi version. The aim of the study is to assess how the proposed modifications will affect the aerodynamics of the vehicle. The most sig-nificant changes concern the rear spoiler and finlets. The aerodynamic properties are assessed based on CFD simulations that are performed for a series production and a modified variant of the vehicle, and the results of which are compared and discussed.

Surface Analysis and Digitization of Components Manufactured by SLM and ADAM Additive Technologies

Pavol Timko, Jozef Holubjak, Vladimír Bechný, Martin Novák, Andrej Czán, Tatiana Czánová

Manufacturing Technology 2023, 23(1):127-134 | DOI: 10.21062/mft.2023.008

The presented article focuses on the surface analysis of the components manufactured by different additive technologies and their reverse digitization. Sintered components were manufactured by SLM and ADAM technologies, while their surface was analyzed using a progressive optical measurement method. To examine the possibility of reverse engineering, the components were optically scanned with a laser scanner and compared to their CAD model. Based on empirical experience, to scan opti-cally the metal and lustrous surfaces is a challenge. The components were manufactured from anti-corrosion materials 17-4 PH and 316L–0407.

Analysis of Cutting Forces with Application of the Discrete Wavelet Transform in Titanium Ti6Al4V Turning

Paweł Karolczak

Manufacturing Technology 2023, 23(4):449-460 | DOI: 10.21062/mft.2023.062

The paper presents the possibilities of using the wavelet transform to filter the cutting force signal. Tests were carried out by dry turning on the Ti6Al4V alloy with variable cutting parameters. Four blades with different nose geometry and coatings were used. From the recorded waveforms, the mean values of the force component Fc and the load stability coefficient were calculated. The measured force waveforms were filtered with Daubechies 4 (db4) and Daubechies 6 (db6) wavelets. From the ratio of the load stabil-ity after filtration to the load stability before filtration, the noise and disturbance values generated during the turning of the tested alloy and the force measurement were estimated. The conducted research shows how the machining conditions affect the values of force, stability, and thus also the variability of the cutting edge load when turning a titanium alloy. They also show the effectiveness of the Discrete Wave-let Transform (DWT) in separating the noise from the force signal.

Structural and Mechanical Properties of CuZn30 Cartridge Brass in Real Production Conditions

Jan Luštinec, Miroslav Roško, Vladivoj Očenášek

Manufacturing Technology 2023, 23(6):846-852 | DOI: 10.21062/mft.2023.090

The paper deals with the technology of production of deep-drawn plates from alpha brass CuZn30. Surface and hidden defects are often observed in these deep-drawn sheets. The research was aimed at reducing the occurrence of these defects and subsequently reducing scrap and increasing the quality of these metallurgical products with a tighter tolerance of the required structural and mechanical properties throughout the length and width of the sheets. The production technology was monitored from the preparation of the batch and casting parameters on the existing operating equipment, through the processing of the ingots by hot and cold rolling, to the recrystallization annealing of the sheets in coils in a hatch furnace and the subsequent continuous pickling and passivation of the final strips. Properties were monitored after each technological operation of production. Specifically, macrostructure, microstructure, microporosity, tensile mechanical properties, and hardness were analysed. The results showed that the chosen production technology has sufficient homogeneity of properties.

Experimental Validation of the Biomechanical Response of an Anthropo-morphic Testing Device (Dummy) at Low Impact Velocities

Karel Jelen, Petr Kubovy, Frantisek Lopot, Lukas Fara, Roman Jezdik, Filip Hrusa, Hynek Purs, Tommi Tikkanen, Martin Novak, Martin Svoboda, Lubos Tomsovsky

Manufacturing Technology 2023, 23(4):418-425 | DOI: 10.21062/mft.2023.047

The paper describes the experimental validation of the biomechanical response of the Hybrid III 50th Percentile Male Pedestrian Dummy (JASTI, Tokyo, Japan) at low impact velocity (up to 2.2 m/s) in comparison with that of human probands. The paper is based on previous research that was focused on the tram-pedestrian crash tests using the same dummy. The biofidelity of the dummy was analyzed in two collision scenarios: the anteroposterior impact (chest impact) and lateral impact (shoulder impact) using a unique pendulum impact testing machine of own design and construction. The primary outcome variable was the peak resultant acceleration of the head and chest during the impact. Based on the lab-based measurements, the unique impact testing machine was found adequate and precise for the purposes of future crash-test analyses in the area of the automotive industry. The proposed methodology and measurement protocol were shown proper to compare the data between the dummy and human participants. Following the pilot experiments, the kinematic and dynamic data between the dummy and human participants were analyzed to assess the biofidelity of the dummy for the frontal and side impact during tram-pedestrian collisions at low impact velocities.

The Effect of Single-Wall Carbon Nanotubes Content on the Properties of Polyurethane Nanocomposite

Dana Bakošová, Alžbeta Bakošová

Manufacturing Technology 2023, 23(5):580-588 | DOI: 10.21062/mft.2023.079

This study aimed to investigate the influence of single-wall carbon nanotube (SWCNT) content on the mechanical properties of polyurethane (PU) nanocomposites. The SWCNT content varied from 0 wt% (reference sample) to 2 wt%. Tensile, hardness and Charpy impact tests as well as dynamic me-chanical analysis (DMA) were performed. Based on the test results it was observed that an increase in the content of single-wall carbon nanotubes resulted in significant improvements in material strength and stiffness. Furthermore, atomic force microscopy (AFM) was used to examine microsurface to-pography of the samples and to obtain spectroscopic curves, based on which local elasticity was eval-uated. Overall, performed measurements indicate that the incorporation of SWCNTs into PU matrix makes resultant nanocomposite stiffer and more resistant to deformation. The results highlight the potential of SWCNTs as effective reinforcement of polyurethane-based nanocomposites.

Flexural and Out-of-Plane Compression Performance of Hexagonal Rubber Wood Core Sandwich with Increasing Cell Wall Thickness

Jennise Tan Teng Teng, Mohd Yuhazri Yaakob, Mohd Amirhafizan Bin Husin, Kamarul Amir Mohamed, Myia Yuzrina, W. Lau

Manufacturing Technology 2022, 22(2):240-253 | DOI: 10.21062/mft.2022.023

This paper investigates the rubber wood honeycomb core by manipulating its cell wall thickness. Rubber wood honeycomb core was fabricated with cell walls range from 1 mm to 3 mm. The impacts of the cell geometrical parameters on the flexural and out-of-plane compression performance are studied. In the case of solid rubber wood without facesheet, the density is much higher than those rubber wood honeycomb composites. The failure can be disastrous without facesheet under bending. Rubber wood honeycomb sandwiches are able to offer the similar specific flexural strength with lower density. With increasing wall thickness from 1 mm to 3 mm, the specific flexural strength increased by 12.32 %. Meanwhile, specific compressive strength improved by 11 % from 1 mm to 2 mm. However, its specific strength dropped by 3.55 % when the wall thickness at 3 mm. Minimum improvement in the compressive strength per density has caused the decrement.

Design of Dual-Head 3D Printer

Vlastimil Chalupa, Michal Stanek, Jiří Vanek, Jan Strnad, Martin Ovsik

Manufacturing Technology 2023, 23(2):177-185 | DOI: 10.21062/mft.2023.032

Fused Filament Fabrication (FFF) printers are usually designed to create a product with one single ma-terial. Some of them allow fabricate items in multiple colours but creating a single product consisting of two different materials remains an advantage of industrial 3D printers only. The aim of this research was to develop a design of a device with two printheads which enables to print products with two different materials, compatible with a cheap and commonly available FFF device Prusa i3MK2S, and the subse-quent production of a prototype. A key aspect of the design was the hardware compatibility of the device with the given printer while maintaining the maximum possible printing area.

Characteristics of Coconut Fibre Combined with Vinyl Ester Composites Through Material Testing and Machining

Muhammad Wafiuddin Suhami, Norfariza Ab Wahab, H. Boejang, Khairum Hamzah, Hiroyuki Sasahara

Manufacturing Technology 2023, 23(5):700-708 | DOI: 10.21062/mft.2023.071

In today's manufacturing industry, composites are widely used. This is primarily due to the highly variable material properties that can be obtained by combining various materials as reinforcements and matrices. However, modern environmental concerns have pushed researchers and engineers to seek materials from organic and renewable sources. The study will look into composite surface roughness during the cutting process, which will involve milling with a CNC router machine. A portable surface roughness tester will be used to obtain a surface roughness average (Ra) reading, and microscopes will be used to examine the composite surface roughness behaviour under a microscope. Based on the results of the experiment, 82 wt.% vinyl ester resin on coconut fibre composite provides the best material properties. With a constant feed rate of 500 mm/min applied to spindle speeds of 5,000, 20,000, and 30,000 rpm, the 5,000 rpm showed the best surface roughness average performance compared to the other two. Further research focusing on feed rates may be required to better deduce the material machining data.

Methodology of Analysis of Fibre Sedimentation in HPC mixtures

Dita Jiroutová, Tomáš Bittner, Karel Hurtig, Tomáš Jirout

Manufacturing Technology 2023, 23(6):819-826 | DOI: 10.21062/mft.2023.106

The aim of this work is to propose a methodology for evaluating inhomogeneity due to the sedimenta-tion of fibres in High-Performnce Concrete (HPC) mixtures. HPC mixtures makes better mechanical-physical properties than ordinary concrete. To achieve higher strengths, the fine-grained matrix is rein-forced with the reinforcement – fibres. The type of used fibres and their homogenization in mixture has an influence on the final mechanical properties of HPC mixture. Four concrete mixtures with same com-ponent proportion was chosen for experiments. Water was the only one component, that was changing in mixture recipes. Steel fibres with a ratio of the diameter to length = 0.3/20 were used as reinforcement. The fibre volume in mixture was 1.5 %. The microscopy analysis was used for evaluation of the fibre dis-tribution in the test specimens. It was obtained, that the concentration of the fibres increases with dis-tance from the surface to the bottom of the HPC structure and this non-homogeneity increases with higher water dosage. The dependence of sedimentation of fibres on composition of HPC mixtures can be used for evaluation and optimization of final mechanical properties of the HPC structures.

Optimization of Threads Production on Thin – Walled Castings

Dana Stančeková, Jozef Mrázik, Anna Rudawska, Miroslava Ťavodová, Izabela Miturska-Barańska, Daniela Sršníková, Miroslav Špiriak

Manufacturing Technology 2023, 23(6):927-934 | DOI: 10.21062/mft.2023.078

This study focuses on the analysis and solution of thread production in thin-walled profiles. It explores three different threading technologies, including cutting, forming, and extrusion. The issue of a screw joint in a thin-walled component is complex due to the stiffness of the joint and the short length of the thread. Hence, the careful choice of a suitable manufacturing process for producing inner threads in thin-walled components holds significant importance. The study entails monitoring the hardening of surface layers of materials after thread production, in conjunction with the acquisition of microstructure images of the experimental material. The outcome is a comparative evaluation of different individual thread production technologies.

Challenges in Tensile Testing of Thermoplastic Composites Reinforced with Chopped Carbon Fibre Produced by Fused Filament Fabrication Method

Jaroslav Majko, Milan Vaško, Marián Handrik, Milan Sága

Manufacturing Technology 2023, 23(2):216-224 | DOI: 10.21062/mft.2023.010

Additive manufacturing is a relatively new technology that has recently undergone noticeable develop-ment, which includes several types of technologies based on the gradual deposition of material in layers. The most widespread method is Fused Filament Fabrication, which belongs to an extrusion technique. The typical feature of extrusion methods is material deposition in the filaments form. Therefore, printer users cannot apply the same approach to products as with conventional technologies. The authors of the paper have been working with the mentioned technology for several years. The primary goal of the research is the investigation how printing parameters affect the mechanical properties of laminates reinforced with chopped carbon fibres. Based on experience and knowledge, the authors report in this article the most common challenges encountered in the preparation process of specimens for tensile testing. This knowledge can also help ordinary users of 3D printers, who also face these challenges without being aware of the impact of these pitfalls on mechanical properties.

Hydrogen Embrittlement of 11SMn30 Free-cutting Steel

Lukáš Šikyňa, František Nový, Peter Palček, Petra Drímalová, Martin Slezák, Milan Uhríčik, Veronika Chvalníková

Manufacturing Technology 2023, 23(6):900-908 | DOI: 10.21062/mft.2023.092

The main objective of the work was to describe the laboratory methods suitable for hydrogenation of free-cutting steels and to study the hydrogen embrittlement of 11SMn30 free-cutting steel. Hydrogenation and subsequent mechanical testing of hydrogenated steel is not common laboratory method as it requires precise and expensive equipment, is time consuming and dangerous as hydrogen is highly reactive and explosive. Currently, there are several theories of hydrogen embrittlement mechanisms of steels that describe the causes of material degradation by hydrogen. However, those theories are not universally valid; individual accounts have been developed and describe hydrogen embrittlement only for specific conditions and may fail in their descriptions under others. In this work, the hydrogenation of free-cutting steel 11SMn30 steel by two different methods (immersion and ca-thodic) was investigated in order to induce embrittlement and to compare in particular the fracture surfaces after the Charpy impact test. The results reported in this paper indicate that manganese sulphide inclusions are not the main cause for hydrogen embrittlement in free-cutting steels. The effect of manganese sulphide inclusions was attributed only to hydrogen trapping, that generated a high stress causing their decohesion from the matrix.

Microstructure, Mechanical Properties and Strengthening Mechanism of Back Extruded WE71 Magnesium Alloy Cylindrical Part

Ting Li, Dehao Bu, Jiawei Yuan, Xiaolei Han, Zhiwei Du, Zhaoqian Sun, Yonggang Peng, Kui Zhang

Manufacturing Technology 2023, 23(4):475-484 | DOI: 10.21062/mft.2023.049

In the present work, the microstructure, crystal orientation, mechanical properties and strengthening mechanisms for different regions of WE71 cylindrical parts have been investigated. The results showed that from inner wall to outer wall, second phases density, DRX fraction decreased but average grain size increased, which is well agree with the strain state and metal flow during back extrusion. For compression area, α//ED texture type can be found in region a, but α directions deflects from ED to TD at a certain angle for region b and c. For shear area, α directions deflects from ED to TD about 10°~45°. For stable forming area, the texture is close toα//ND. After peak ageing, a large number of nanometer scaled β' phases were formed and uniformly distributed in the Mg matrix, while zigzag GP zone and RE-hexagons precipitates can also be found in the peak-aged alloy. Tensile properties for region c in compression area are the lowest: UTS, YS and EL are 322 MPa, 215 MPa and 2.5%, respectively. Furthermore, for the stable forming area, the UTS, YS and EL of 283 MPa, 187 MPa and 19% in the region f are the highest, but the strength of region g is the lowest, which is related to the grain size and volume fraction of second phases on flow lines. The strengthening contributes from fine-grain strengthening, texture strengthening and Orowan strengthening.

Determination of the Effect of Deformation on the Corrosion Resistance of Zn-Al-Mg Coated Sheets

Martin Švec, Iva Nováková, Pavel Solfronk

Manufacturing Technology 2023, 23(5):709-716 | DOI: 10.21062/mft.2023.080

In the automotive industry, deep-drawn sheet metals are widely used and protective coatings are ap-plied to its surfaces to improve certain performance properties (e.g. to increase corrosion resistance). Sheets with these coatings are stressed during the forming process of the part and cracking of the protective coating may occur. The main goal of this paper is to determine the resistance of a Zn-Al-Mg based protective coating to uniaxial and triaxial stresses, and also to determine how effective anticorrosion resistance the coating provides to the base steel matrix in the event that cracking occurs. It has been shown that both uniaxial and triaxial loading leads to a failure of the Zn-Al-Mg coating integrity. Salt spray corrosion tests of 3 and 6 weeks were subsequently performed on both deformed and undeformed base material samples. These tests showed that a continuous Al2O3 layer is formed between the steel matrix and the coating, which, irrespective of the formation of cracks in the coating, is the main contributor to the increase in corrosion resistance of the sheet.

Influence of Heat Treatment Regime on Corrosion Resistance of Clad Aluminium Alloy

Sylvia Kusmierczak, Frantiska Peslova, Natasa Naprstkova

Manufacturing Technology 2019, 19(4):624-631 | DOI: 10.21062/ujep/345.2019/a/1213-2489/MT/19/4/624

Al-Cu-Mg based alloys are often used in the automotive industry. There are characterized by high strength characteristics but poor corrosion resistance, which appears to be problematic in this sector. The manufactured blanks of these alloys may be protected by some of the barrier protection methods, including cladding. Semi-finished products made of these methods can be protected against corrosion by a thin layer of aluminium oxides - called clad Durals. The surface layer creates a stable and durable Al2O3 layer, which provides corrosion resistance, which leads to an extended service life of the piece.
However, this type of protection is adversely affected by the effect of copper diffusion, which is dependent on the heat treatment mode of the alloy. Temperature and temperature hold are the main factors influencing the diffusion process. In the solution annealing of aluminium alloys, the temperature is in the range of (470-500) ° C, resulting in intense diffusion processes at the inter phases interfacial.
The paper deals with the analysis of the influence of the heat treatment regime on the corrosion resistance of Al2024 alloy sheets (AlCu4Mg1 type alloy) provided with an Al1050 alloy clad coating on both sides in a corrosive salt mist environment in accordance with EN ISO 9227, which is supposed to have a positive effect on extending the service life of a car component.

The Effect of Boriding and Heat Treatment on the Structure and Properties of 100Cr6 Steel

David Bricín, Antonín Kříž, Jan Novotný, Zbyněk Špirit

Manufacturing Technology 2022, 22(1):2-9 | DOI: 10.21062/mft.2022.003

The main aim of this case study is to present the changes caused by heat treatment on the structure and properties of 100Cr6 steel by annealing, hardening, and tempering in combination with previous chemical-heat treatment (CHT) by boriding. The boriding causes changes to the microstructure of the steel samples, which include a change in the morphology of the deposited cementite and a change in the volume of the chromium carbide particles. The cementite is transformed from its original granular form to a lamellar form. An increase in the proportion of chromium carbide particles in the sample occurs due to the higher affinity of chromium for carbon. This leads to precipitation of chromium carbides rather than carbides of iron. A multi-phase diffusion layer Fe2B-FeB with a thickness of 31 ± 2.8 µm is formed during boriding, with a typical tooth-like texture. Although the diffusion layer does not have the same toughness and resistance as the single-phase Fe2B diffusion layer, samples after boriding increase their resistance to tribological abrasion by 29 % compared to samples without this treatment. After quenching and tempering of the borided samples, a maximum tensile strength of Rm = 1779 MPa is measured. Compared to samples which are only quenched and subsequently tempered, this is an increase in tensile strength of about 59 %.

Microstructure and Phase Composition of Thin Protective Layers of Titanium Aluminides Prepared by Self-propagating High-temperature Synthesis (SHS) for Ti-6Al-4V Alloy

Anna Teichmanova, Alena Michalcova, David Necas

Manufacturing Technology 2022, 22(5):605-609 | DOI: 10.21062/mft.2022.069

Titanium aluminides were prepared using self-propagating high-temperature synthesis (SHS) from powder aluminium and compact Ti-6Al-4V alloy at 800 °C. The resulting material was subsequently annealed at the same temperature for 3 hours. The coating was successfully bonded to the matrix using SHS while forming intermetallic phases of cubic TiAl3 in areas of powdered aluminium. The resulting coating was approximately 14 μm thick. Material annealing resulted in further reactions between the TiAl3 coating and Ti-6Al-4V matrix, forming a thin layer of γ-TiAl. Using SEM, the different phase composition of annealed and unannealed material was clearly visible, however, clear determination of emerging phases was very difficult due to the small thickness of the intermetallic coating. Eventually, phases were determined by a combination of cross-section μ-XRD and various EDS analyses.

Study of Coatings Intended for Active Parts of Forming Tools Produced by Powder Metallurgy

Elena Kantoríková, Ján Moravec

Manufacturing Technology 2022, 22(1):20-25 | DOI: 10.21062/mft.2022.005

The article deals with new types of coatings and their mechanical properties. CTRN and CRONAL are newly developed coatings intended for active parts of forming tools. Their behavior and mechanical properties are still under investigation. Coatings are used for functional components in various areas of industries, their de-velopment is constantly in process. The aim of the study and the experimental solution provides a compari-son of the mechanical properties of the new coatings with the well-known coatings DLC, TiN and TiSiN. The aim of the work was to perform an analysis of CTRN and CRONAL coatings and compare their me-chanical properties with other coatings. We chose the methods of nanoindentation, hardness measurement, scratch test and layer roughness. The results will allow easy determination of the proper coating for a suitable material. The results present the specific functionality of the individual coatings.

Properties of MgCaZr Alloys

Jan Serak, Cyril Simon, Dalibor Vojtech

Manufacturing Technology 2022, 22(4):461-470 | DOI: 10.21062/mft.2022.054

The use of most commercial magnesium alloys is limited to working at normal temperatures. The excellent ratio between the mechanical properties and the density of magnesium alloys necessarily leads to the development of new types of alloys that would be usable even at elevated temperatures. This would significantly increase the applicability of these alloys where steels or aluminum alloys are still used, especially in the transport industry. The problem with today's high temperature resistant magnesium alloys is the need to use expensive rare earth alloys. Significantly cheaper alloys of magnesium with zirconium and calcium are studied in this work. The microstructure, mechanical properties under pressure at the temperatures of 20, 150, 200 and 250 ° C were studied for several alloys with different contents of Zr and Ca. Furthermore, the stability of alloys during their long-term temperature exposure was studied. A very positive effect of the studied additives on the properties of alloys was found, which gives these alloys a very promising perspective in the future.

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