Key Engineering Materials Vol. 822

Abstract: There are given the results of the evaluation of the starting polymers properties and the properties of the resulting WPC. The industrial objects of WPC based on various polymers were chosen as the objects of the study. In order to analyze the structure of the WPC there was used a computer microtomography, one of the recent non-destructive methods for studying the bulk structure of composites using X-ray radiation. To assess the overall durability and behavior of the end products under actual operating conditions, tests were carried out in special artificial weather equipment (weatherometer).

Abstract: While producing polymers as well as during their processing, a certain amount of stabilizers is introduced into the product, which should ensure polymer properties saving during processing and those of polymer products during storage and operation. However, in cases where medical products based on polypropylene are subjected to radiation sterilization, there are not enough stabilizers in it to save their characteristics during operation. In this regard, we made an assessment of the influence of processing conditions on the properties of polypropylene with a different set of stabilizers in the manufacture of products based on it, in order to assess the degree of influence of each technological operation, including the effects of ionizing radiation during sterilization. Processing and radiation exposure are shown to affect the properties of polypropylene. Nevertheless, the effect of ionizing radiation with an absorbed dose of 40-60 kGy exceeds the negative effect of thermo-oxidative breakdown greatly during the extrusion of PP. Polypropylene containing organophosphorus stabilizers (brand PP 1562R) is more susceptible to breakdown. This is indicated by low values of oxidation induction time, breakdown initial temperature, as well as high values of MFI after exposure to electron radiation. PP brand PP H350FF/1 whose stabilizing complex contains phenol-phosphite antioxidants is more resistant to breakdown during processing and sterilization. For both brands under study, it is apparently necessary to increase the content of stabilizing additives in order to save the properties at the level of the original unexposed material.

Abstract: In this paper, a complex study of composite materials of different nature for the presence of internal defects after the application of impact damage was carried out. The dependence of the initiation energy on material damage from the magnitude of the impact energy is obtained. The areas of sample bundles were investigated by ultrasonic testing (UT). The structure of samples from composite materials was monitored using an industrial microtomography system. A technique was developed that allows highly accurate determining the size of internal sample defects by means of computed tomography (CT).

Abstract: The publication is described direct laser deposition of high-strength cold-resistant steels results. Results of corrosion, abrasive-corrosion and tribotechnical tests are shown.

Abstract: Laser technologies deservedly take their place in modern mechanical engineering production. Using laser source for welding has already become common. However, the creation of critical welded constructions is impossible without extensive technological surveys, which can be greatly simplified by using a computational experiment. To achieve this goal, special programs are usually used. That can be unjustified difficult and thereby awkward for technological practice. The article describes an application built on the basis of a simplified model for calculating the temperature field for the cases of laser and laser-arc welding of internal fillet welds as well as single-sided T-joints and simultaneous double-sided welds. The results of calculations by the model and comparing them with experimental data have shown that it is sufficiently adequate for use in technological purposes. The developed application contemporaneously has a simple and intuitive interface, does not require significant computational resources and can be used for quick preliminary estimation of the result of welding for the selected type of weld.

Abstract: DLD, also known as Direct Laser Deposition, is an approached manufacturing technology. It is used to build full density metal parts directly from CAD files without using any modules or tools. A close look over the chemical composition and the microstructure of nickel based alloys will be shown in this paper.

Abstract: The shape of the parts, created by the technology of direct laser metal deposition (DLMD), is influenced by various parameters, for example, the power and diameter of the laser source spot. The contribution of energy from the laser affects the temperature distribution in the formed layers. The changing temperature in the working area entails a change in the geometry of the layers and affects the stability of the process. In this paper, experiments on the measurement of temperature cycles in the DLMD process with different directions of the filling track are carried out. An infrared camera was used to measure thermal cycles. The correspondence table between the intensity of thermal radiation of the material and the absolute temperature was developed. The experiments are carried out with the filler material 316L. The effect of the maximum temperature on the layer height is shown, and thermal cycles in the formation of layers for different filling strategies are presented.

Abstract: This article is devoted to Inconel 718 heat-resistant nickel alloy. Comparison of samples obtained by high-speed direct laser deposition technology of powders from different manufacturers on their structure and properties was carried out. The dependence of the influence of the chemical composition of the powders on the formation of defects in the studied samples was established

Abstract: Effect of process parameters of microstructure formation and mechanical properties of direct laser deposited parts of cold-resistant steel 09CrNi2MoCu is studied. Due to local properties of buildup depends on thermal cycle during fabrication simulation of temperature field was carried out. The following cases were analysed: deposition of the first layer on massive substrate and deposition of a layer on the buildup far from the substrate. It was established that one time high temperature reheating of deposited layer has no effect on hardness while additional reheating up to lower temperature leads to considerable decrease in hardness by 87-100 HV. Far from substrate hardness and microstructure bands of 0.7-0.8 mm thickness have a hardness variation in the range of 250-300 HV. The area close to the substrate has a microstructure of upper bainite with higher hardness due to higher cooling rates during deposition. In the process of deposited, at a higher power, a quick process of heating and cooling occurs, and vice versa, which forms various products of bainite transformation. From the obtained modes were presented the results of tests for impact strength at low temperatures.

Abstract: Review focuses on describing of mechanical properties of the components manufactured via direct laser depositionfrom cold resistant steel material. The results of tensile and impact testing are presented and microstructures of the fractures are shown. The process of laser deposition of cold-resistant steels, the formation of structures, as well as the mechanical properties of these samples are poorly understood. The results of tensile and impact tests are presented, and microstructures are shown. Mechanical tests for impact strength were carried out at a temperature of -40˚С, with different laser radiation powers. The results are given using the as-received powder, as well as used powder with a different mixing ratio, and the results are analyzed. As a result of the study, it was found that the fractional composition of the 09XH2MD alloy powder affects the mechanical characteristics of samples obtained by direct laser deposition. The effect of recycled powder on the mechanical properties of the obtained samples is given, the optimal laser deposition regimes are selected