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The article discusses the phenomena and destructive mechanisms occurring on the surface of 1.2344 steel dies used during the hot forging of disc-type forgings. Preliminary research has shown that gas nitriding alone, used so far, is insufficient due to the occurrence of destructive mechanisms other than abrasive wear, such as thermal and thermomechanical fatigue, which cause the average durability of such tools to be approximately 5000 forgings. Analyses were also carried out to assess the load on forging tools using numerical modeling (Forge 3.0NxT), which confirmed the occurrence of large and cyclically changing thermal and mechanical loads during the forging process. Therefore, in order to increase operational durability, it was decided to use two types of hybrid layers, differing in the PVD coating used: TiCrAlN and CrN, and then subjected to gas nitriding (GN). The obtained results showed that, depending on the area of the tool and the current working conditions, the applied PVD coatings protect the surface layer of the tool against the dominant destructive mechanisms. In both cases, the strength increased to the level of 7000 forgings, the tools could continue to work, and globally, slightly better results were obtained for the GN+TiCrAlN layer. The CrN-type layer protects the tool more against thermal fatigue, while the TiCrAlN layer is more resistant to abrasive wear. In areas where the hybrid layer was worn, a decrease in hardness was observed from 1300 HV to 600–700 HV, and in places of intense material flow (front—point 2 and tool bridge—point 9) the hardness dropped to below 400 HV, which may indicate local tempering of the material. Moreover, the research has shown that each process and tool should be analyzed individually, and the areas in the tool where particular destructive mechanisms dominate should be identified, so as to further protect the forging tool by using appropriate protective coatings in these areas. [ABSTRACT FROM AUTHOR]

The need to determine the sex of the fetus in early pregnancy is usually based on medical indications for early implementation of appropriate therapeutic procedures, and is sometimes driven by parental curiosity. Medicine has made tremendous progress in early diagnosis of fetal sex in the last decades. The diagnostic methods described in the literature are characterized by varying degrees of accuracy, cost, and potential risk to the fetus. For these reasons, there is an ongoing debate about when and in which cases a particular method should be used. This paper presents an overview of the current methods of fetal sex determination. [ABSTRACT FROM AUTHOR]

This paper presents research results in the field of industrial die forging, mostly related to the use of advanced measuring techniques and tools, numerical simulations, and other IT tools and methods for a geometrical analysis of the forged items as well as detection of forging flaws and their prevention, and optimization of the hot-forging processes. The results of the conducted investigations were divided into three main areas. The first area refers to the application of, e.g., optical scanners and programs related to their operation, data analysis, including the construction of virtual gauges, measurements of selected geometrical features of both the manufactured forgings and their physical and virtual models, as well as an analysis of the durability of the forging tools based on the proprietary reverse scanning method. The second area presents the results of measurements and analyses performed with the use of finite element modeling and by means of some special functions in the calculation packages, such as contact, flow lines, trap, or fold, for the detection of forging defects and an analysis of the force parameters. In turn, the third area presents a combination of different methods of measurement and analysis, both FEM and scanning, as well as other IT methods (physical modeling, image analysis, etc.) for the analysis of the geometry and defects of the forgings. The presented results point to the great potential of these types of tools and techniques in forging industry applications as they significantly shorten the time and increase the accuracy of the measurement, as well as providing a lot of valuable information, physical variables, and technological parameters that are difficult or impossible to determine either analytically or through experimental means. The use and development of these techniques and methods are fully justified, both in the aspect of science and the increased effectiveness and efficiency of production. [ABSTRACT FROM AUTHOR]

One of the basic conditions for the sustainable development of a modern city is the presence of a developed and efficiently functioning system of green infrastructure. It consists of all natural resources: greenery areas (gardens, parks, squares, street shelters, green roofs, etc.) and spontaneous (urban forests, green wastelands, etc.), water (watercourses and water reservoirs). Taking into account the specific, usually unfavorable conditions of the urban environment and the strong anthropopressure occurring there, all forms of vegetation should be subject to comprehensive management, including among others, the successful development of new facilities and plantings, as well as protection with the constant control and maintenance of existing valuable resources [2]. The long-term studies of the condition and transformations of urban tree stands [1, 3, 4, 5, 6] conducted by the authors allow the formulation of a set of recommendations at the implementation level to ensure the efficient functioning of the green infrastructure in the city.

Introduction: Ultrasound examination of pregnant women to assess the anatomy and normal developmental parameters of the fetus has been a standard in obstetrics since the 1980s. Nowadays, attempts are being made to identify sex in early pregnancy. The method of fetal sex determination based on cytogenetic evaluation of fetal cells isolated from maternal blood and free fetal DNA detectable in pregnant women's blood, developed in recent years, requires a specialised laboratory. In view of these conditions, it seems obvious and necessary to search for alternative methods of fetal sex determination at the earliest possible stage of pregnancy. Therefore, the aim of the present study was to determine the sex of the fetus in the I trimester of pregnancy. Materials and methods: The initial study included 187 pregnant women who were between 5-10 weeks of gestation (model 1) and the actual study included 240 subjects who were between 5-13 weeks of singleton pregnancy (model 2). A logistic regression model was used to assess the probability of fetal sex based on crown-rump length (CRL), gestational sac volume (GSV), and gestational age. Results: The study indicates that the sex of the fetus can be predicted with a high probability from ultrasound earlier than previously thought. Conclusions: After 7 weeks of gestation, differences in the size of male and female fetuses start to become apparent. Male fetuses have on average higher CRL and GSV than female fetuses. This allows predicting male sex with a significantly higher probability. [ABSTRACT FROM AUTHOR]

The paper presents the results of numerical studies of the process of extrusion of a new N-type section for the purposes of the automotive industry. Model studies were carried out using Forge®NxT, a finite element methodbased software program. The test material was an Al alloy in Series 6xxx. Prior to proceeding with the modelling of the extrusion process, rheological tests were performed on this alloy for deformation parameters corresponding to the technological process of extruding large-size sections in the conditions of one of the domestic extrusion plants. The effect of hot deformation conditions on the variations in yield stress magnitude was determined. Then, using the least squares method, the actual values of the coefficients of the mathematical model describing the rheological properties of the material under study were determined. [ABSTRACT FROM AUTHOR]

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecological Engineering / Inżynieria Ekologiczna is the property of Polish Society of Ecological Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of tests conducted on extruded, thin-walled (wall thickness approx. 1.2 mm) closed shapes made of AW-6082 alloy. Shapes were extruded using the bonding extrusion method, by means of 6-hole dies. Sections cooled in three ways at the exit from the press were tested: water spraying, water cooling with a socalled "water wave" and air blowing. A methodology of testing was developed, allowing for assessment of the plastic formability of extruded shapes, mainly through bending and expanding. AW-6082 alloy is more difficult to extrude than 6063 or 6060 alloys, since its higher strength and lower plasticity make it difficult to obtain walls of low thickness and high extrusion rate. As demonstrated in previous studies, such shapes achieve very good strength properties, reaching up to Rm = 340 MPa, but they are characterized by limited plastic formability. This paper presents the results of bending, buckling, expanding and flexion tests on a three-roll machine. It was determined that the maximum compressive force determined in the buckling test of a segment 650 mm in length, indicating the greatest resistance to buckling, corresponds to shapes cooled by means of a so-called "water wave" on the coasting of the press. These shapes were also characterized by the greatest deflection in the three-point bending test. The elevated plasticity and plastic formability of these shapes was confirmed in a cone expansion test, where relative deformation values were 35% greater than in the case of shapes cooled by air blowing or water spraying. Metallographic examinations revealed that crack initiation in the expansion test occurs at welds in shapes, and enlarged grain size was observed in these areas. [ABSTRACT FROM AUTHOR]

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of tests of the mechanical properties of aluminium alloys 5754, 5083, 5019 and AlMg7. The alloys with magnesium reach satisfactory mechanical properties, and their corrosion resistance is even 3 times that of the most commonly used alloys of the 6xxx series (AlMgSi), making them a desirable material in many branches of industry. The necessity of applying lower extrusion speeds and much lower deformability of the 5xxx series alloys as compared to the 6xxx series are the reasons why extrusion is more rarely applied as the technology of manufacturing details from these materials. In order to compare the mechanical properties of the alloys mentioned above, a static tensile test of samples taken from aflat open section has been performed. It was found that mechanical properties increase with the growth of magnesium content (from Rm of 220 MPa at 3.5% Mg content to 290 MPa at 5% Mg content) while maintaining similar plasticity at the level of 25% Ago mm elongation. Additionally, a three-point bending test was performed on samples taken from the section in the transverse direction. Samples were loaded within the elastic range in order to determine the deflection. It was determined that profiles extruded by a nonstandard die (enlarged size of pre-chamber and corrected die land, relative to standard die) exhibit slightly higher stiffness than those extruded by the standard die used for extruding 6xxx alloys. Next, curves of reduced bending stress og as a function of relocation were determined, and bending strength, Rg, was determined on their basis. The paper also presents the results of the static tensile test of whole pipes, extruded by a porthole die, with an outer diameter of 42 mm and wall thickness of 3.5 mm. No significant differences in the properties of closed sections as compared to the open ones were found, which proves that the weld does not influence the strength properties of the sections in the longitudinal direction. [ABSTRACT FROM AUTHOR]

This paper presents the results of tests of the properties of hollow thin-walled (wall thickness approx. 1.2 mm) shapes made of AW6082 alloy in T5 state. Shapes were extruded using the bonding extrusion method, by means of 6-hole porthole dies. Extrusion parameters were optimized by changing the rate of extrusion and cooling. Mechanical properties, hardness, wall thickness and surface coarseness of shapes subjected to extrusion at various rates (9, 10 and 12 m/min), cooled on the press coasting at different cooling rates (water spray, water wave), and artificially aged at a temperature of 180oC over 2 hours, were determined. Based on the tests, it was found that high mechanical properties and a uniform, finegrained structure were successfully achieved at the highest applied extrusion rate of 12 mm/min. Based on the shape thickness measurements, it was determined that, despite achievement of a product of satisfactory thickness tolerance, it is necessary to correct the die to obtain more uniform distribution. The change of the wall thickness of the oval shape results from the complexity of the die orifice and also from the die deflection during extrusion, which is difficult to predict at the designing stage. Extrusion rate also has an impact on the surface quality of the shape, which is expressed by the parameter of coarseness Ra, and this quality was lowest for extrusion at a rate of 9 m/min. As a result of an increase in extrusion rate from 10 to 12 mm/min, coarseness is reduced, improving surface quality. The change in cooling rate from air cooling to water spraying or by means of a so-called water wave caused an increase of strength to the level assumed and desired by the end recipient, i.e. Rm, > 310 MPa, but at the same time, did not have an impact on the significant reduction of relative elongation A. [ABSTRACT FROM AUTHOR]

Aluminum-based bearing materials are widely used for automotive applications. One special advantage is the weight savings associated with using aluminum alloys. However, the effect of submicro- and nanostructure on the tribology behavior of these materials is not studied in detail. The effects of normal load and sliding velocity on the frictional behavior of nanostructured aluminum alloy against steel is not studied yet. The paper contains the results of tribology examination of nanocrystalline (NC) aluminum alloy NC A2017. The possibilities of use of these materials obtained by the method of hydrostatic extrusion, in various friction units look very promising. It is found the 2017 aluminum alloy with nanometric structure exhibits low friction coefficients at low normal loads. From other side the NCA2017 aluminum alloy can be successfully formed 200°C and above. Plastic deformation of the material above 200°C causes noticeable grain growth. However, the determined average grain diameters are in the submicron range, even for compression temperature of 300°C. The friction behavior of NC 2017 Al alloy is characterized by three times anomalous fall of friction coefficient up to f=0.15 as compared with f=0.45 for coarse grained 2017 Al alloy. The wear rate of NC 2017 Al alloy is diminished by three times as compared to that of coarse grained 2017 Al alloy. The possible reason of such a behavior is the specific features of nanostructure and precipitates of NC 2017 Al alloy. [ABSTRACT FROM AUTHOR]

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work attempted to demonstrate the dependence between die geometry, connected to the shapes of aluminium profiles and the parameters of the nitriding process, to the die's service life. Dies were subjected to single or repeated gas nitriding and used until worn out at the company Albatros Aluminium. The article undertakes an attempt to explain the influence of various nitriding processes and die geometries on the thickness of the nitrided layer and the durability of the die. Based on the research, the optimal thickness of the nitrided layer was determined to be in the range of 350-400 µm. The use of a smaller thickness causes faster wear or damage to the dies. [ABSTRACT FROM AUTHOR]

In this publication are presented the results of SEM examinations of the structure and distribution of Vickers HV 0.1 hardness in open and closed dies (die cores) made from WCLV steel for extrusion of aluminum profiles, whose surface layer had been hardened as a result of a two-step gaseous nitriding with the Zero Flow method. The main processes causing wear of the studied dies were determined. Dies with the aforementioned nitrided layers can fulfill requirements for operational durability in the case of medium production runs of aluminum profiles, without needing to undergo regenerative processes. [ABSTRACT FROM AUTHOR]

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metal Forming / Obróbka Plastyczna Metali is the property of Instytut Obrobki Plastycznej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)