Advanced Materials Research Vol. 1036

Abstract: 1. Theoretical aspects

Abstract: For going of the durability of the machining tools at the making of mild steel is proposed the andvanced straining, process which was applied in practice at the broaching the parts of holes valve rocker type. In this paper we propose to present some of specific aspects on the combined splinting and deforming process on internal and external sorfaces.

Abstract: The use of cutting fluids in turning can change thermomechanical loading of cutting tools. Currently, manufacturers provide a wide range of cutting fluids, which have different combinations of lubricating and cooling properties. Depending on cutting conditions, this combination can reduce tool wear in different degrees, and, in some cases, to even increase it. Therefore, an effective choice of cutting fluids requires a considerable amount of experiments, which requires cost and time. To solve this problem in the software SIMULIA/Abaqus Explicit 6.10 was developed thermomechanical model of the turning process by cutting tools with PVD-coating, which allows simulating the effect of any combination of cooling and lubricating action. An Arbitrary Lagrangian-Eulerian formulation method was used in the modeling. Under the lubricating and cooling action is understood the final result of interaction of cutting fluids with the cutting zone. Modeling of lubricating action of cutting fluid is performed by introducing into the model corresponding average coefficient of friction in the contact zone of cutting tool, worked material and cutting fluid. Modeling of cooling action of cutting fluids is implemented through the introduction of the heat transfer coefficient, calculated on the basis of cutting conditions and thermo-physical properties of cutting fluids. As an example, turning of austenitic stainless steel X10CrNiTi18 by carbide cutting insert with TiN-coating for a predetermined cutting condition was examined. A selection of cutting fluids of the proposed range, formulations of which have different combinations of cooling and lubricating properties ("Unizor-M", "Ferrobetol-M", "EkoEM-1", "STARCUT E9", "SAFECUT M120") was accomplished through the simulation model and the calculated data contact stresses. Experimental studies have confirmed the validity of this choice by comparing the rate of flank tool wear in the using different cutting fluids. The rate of wear was determined by surface micrographs of flank tool. An application of the recommended cutting fluid "SAFECUT M120" has reduced wear by 4 times as compared with the application of the "Ferrobetol-M", the use of which has shown the highest wear. The model developed can be used for selecting a predetermined range of cutting fluids, in determining the optimal combination of lubricating and cooling actions for establishing the required characteristics of cutting fluid or in developing new formulations of cutting fluids.

Abstract: The influence of the nitrogen content in argon/nitrogen gas mixture on mechanism of titanium nitrides formation during laser surface processing of titanium alloy Ti6Al4V with high power diode laser was investigated. The phase composition and microhardness on cross-section of surface layers were analyzed and described. It was found that the nucleation of TiN dendrites in nitrogen rich atmosphere (at least 75 % of N₂) takes place on the liquid/gas boundary as a result of the reaction between molten titanium and gaseous nitrogen. The subsequent growth of titanium nitride dendrites (crystallization) proceeds into the liquid metal (weld pool), perpendicularly to the top surface. High length of the titanium nitride dendrites up to 180÷250 μm in the surface layer produced in pure nitrogen atmosphere indicates also very rapid rate of dendrites growth in the molten titanium. The tendency to form titanium nitrides during laser surface processing of the investigated titanium alloy falls dawn with the decrease of nitrogen content in the gas mixture.

Abstract: 800x600 Like all industrial processes, injection molding can produce flawed parts. In the field of injection molding, troubleshooting is often performed by examining defective parts for specific defects and addressing these defects with the design of the mold or the characteristics of the process itself. Trials are often performed before full production runs in an effort to predict defects and determine the appropriate specifications to use in the injection process [1]. Gate solidification time is important, as it determines cycle time and the quality and consistency of the product, which itself is an important issue in the economics of the production process. Holding pressure is increased until the parts are free of sinks and part weight has been achieved. [2] The number of triangle in the mesh has an impact on calculation times. Each triangle has three nodes and the calculations done by the SolidWorks Plastics solvers are performed at each of those nodes. So, a higher number of elements mean a higher number of nodes and as the number of nodes increases, compute time increases. That said, element counts up to 100,000 should solve in a reasonable time, while element counts over 100,000 may take longer to solve. Gates vary in size and shape depending upon the type of plastic being molded and the size of the part. Small gates have a better appearance but take longer time to mold or may need to have higher pressure to fill correctly. Large parts will require larger gates to provide a bigger flow of resin to shorten the mold time. In this paper we will study the influence of the gate shape and location over the specimen. We will study in particular the fiber orientation for a material reinforced with fiberglass.

Abstract: Titanium alloys belong to a group of the most advanced metal materials with increasing applications observed in recent years, mainly in the aircraft, shipbuilding, automotive and chemical industries as well as in medicine. In the paper, results of the study on changes in aluminium content in binary Ti-Al alloys during smelting in the vacuum induction melting (VIM) furnace are presented. The experiments were performed at 5 Pa and 1000 Pa, 1973 K and 2023 K. The investigations were conducted for alloys containing up to 49%mass Al. Each experiment began with loading an alloy sample (about 1000 g) into the graphite crucible placed in the induction coil of the furnace. After closing the furnace chamber, the pre-specified vacuum was generated with the use of a pump system. When the pressure level was stabilised, the crucible was heated up to the required temperature and the metal bath was held for 600 sec. During each smelting experiment, metal samples were collected and subjected to a chemical analysis. The Al loss rate in each experiment was not higher than 21%; it increased with temperature and reduced pressure in the device. It is assumed that the observed loss of aluminium during smelting is the effect of evaporation. The obtained values of Al concentration in the investigated alloys ensured that the aluminium overall mass transfer coefficient in the process could be estimated. The values of overall mass transfer coefficient were 0.88 to 1.66×10^-5 [m·s^-1]. Lack of clear effects of the alloy composition on the analysed process rate proves that it is not controlled by mass transfer in the liquid phase.

Abstract: The paper presents the effect of alloying with WC and TaC powders on structure and mechanical properties of the X40CrMoV5-1 steel surface layer using the HPDL (High Power Diode Laser). The metallographic investigations on light microscope show that during alloying the X40CrMoV5-1 hot work tool steel with the WC and TaC powder the obtained run face is characteristic of the high roughness, multiple pores, irregularity, and flashes at the borders. The changes of the surface layers hardness formed as a result of alloying with ceramic powders containing carbides are accompanied with the increased tribological properties. The microstructure of the alloyed layers which were formed on the surface of the investigated hot work steel was examined using optical microscope. The tribological wear relationships using pin-on-disc test were specified for surface layers subject to laser treatment, determining the friction coefficient, and mass loss of the investigated surfaces.

Abstract: The purpose of this paper was the investigation of laser treatment influence on the microstructure and properties of the surface layer of heat treated Al-Si-Cu cast aluminium alloys, using the high power diode laser (HPDL). The performed laser treatment involves remelting and feeding of ZrO₂ ceramic powder into the aluminium surface. Based on the performed investigations it was possible to obtain the layer consisting of the heat affected zone, transition zone and remelted zone, without cracks and defects as well as has with a slightly higher hardness value compared to the non remelted material. The laser power range was chose as 1.5 to 2.0 kW and implicated by one process speed rate of 0.25 m/min. Also a powder size was used for alloying with the particle size of ca. 100 μm. The hardness value increases according to the laser power used so that the highest power applied gives to highest hardness value in the remelted layer [1-8]. The carried out investigations allow to conclude, that as a result of alloying of the heat-treated cast aluminium alloys with oxide ceramic powder the surface layer can be enriched with the powder particle and in some cases a high-quality top layer is possible to obtain. Very often to determine conditions of laser treatment are being used the numerical methods that would significantly shorten the time to find the most optimal parameters. [8]. Concerning original practical implications of this work there was important to investigate the appliance possibility of High Power Diode Laser (HPDL) for enhancement of the aluminium surface properties, especially the wear resistance and hardness. the scientific reason was also to describe structure changes and processes occurred in the laser remelted surface aluminium layer after ZrO₂ feeding using HPDL laser [10-1. .

Abstract: The article focuses on mild steel welding and covers the new possibilities of that method. Since 2011 innovate welding technology based on micro-jet cooling just after welding is being checked. Weld metal deposit (WMD) was carried out for standard MIG welding and for new welding method with micro-jet cooling. A very high percentage of acicular ferrite (AF) in WMD was gettable (55-75%) for low alloy welding with micro-jet cooling injector. This beneficial structure (very high amount of AF) is unusual to observe in WMD in other welding methods. This method is very promising mainly due to the significant improvement of weld quality and reduces costs. Furthermore impact toughness and strengths of WMD were carried out. The present paper aims at outlining same of the recent innovations in MIG welding which represent steps ahead to achieve the objectives outlined above.

Abstract: New technology of micro-jet welding could be regarded as a new way to improve plastic properties of welds. The main purpose of that paper was analysing of plastic properties of welds made by MIG welding method with micro-jet cooling. The main reason of it was investigate possibilities of getting better plastic properties of welds made by MIG welding method with micro-jet cooling than plastic properties of welds made by ordinary welding method. It is possible for steel because higher amount of acicular ferrite (AF) in weld metal deposit (WMD) is obtained in MIG welding method with micro-jet cooling in relation to ordinary welding method (example: MIG welding method without micro-jet cooling). Moreover, it is possible to steering of weld structure and properties of the weld. During research Erichsen cupping tests and bending tests were carried out for welds made by MIG welding method with micro-jet cooling and ordinary welding method (MIG). Different kind of cooling gases were used to weld cooling. In this case comparison of plastic properties for different cooling gases was done. High amount of acicular ferrite influences positively on plastic properties. Higher values of plastic parameters were observed for welds made by MIG method with micro-jet cooling than for ordinary welding method. Different plastic properties were obtained for different cooling gases. In this research welds made by new method of welding (welding with micro-jet cooling) were compared witch welds made by ordinary welding method. New method of welding is very promising and capable of industrial application, mainly due to the significant improvement of weld properties and quality. That research was made only for steel welding with using MIG welding method. Another method of welding and another material were not tested. Other methods of welding have not been tested, but it is suspected that similar phenomena are taking place. Practical implications MIG method with micro-jet cooling it is way to get better plastic properties of welds in relation to welds made by ordinary welding method. It is very important because it could be used to steering of mechanical properties of welded constructions. This may have a positive impact on the parameters of the welding process (example: welding speed) and the quality of welded joints.