Materials Engineering - Materiálové inžinierstvo (MEMI - E-Journal)
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Thermal, structure and phases analysis of the aluminium ENAC-AlMg5Si2Mn alloy
Get PDFThe microstructure that is attributable from the specific casting method dictates further mechanical and physical properties of the material. In order to understand how to control the microstructure of the casting, it is important to understand the changes in microstructure during crystallization. The work focused on thermal analysis, metallurgical characterization and laser treatment of an aluminium alloy. The research show that the thermal analysis carried out on UMSA Technology Platform is an efficient tool for collect and calculates thermal parameters. The paper contributes to better understanding non-equilibrium metallurgical characterization of aluminium alloys. The solidification of the aluminium dendritic network, iron containing intermetallic phases, the aluminium-silicon eutectic and magnesium containing intermetallic phases were characterized.
Differences in the surface texture of aggregate particles determined by 3D model derived from optic microscope measurements
Get PDFoai:ojs.pkp.sfu.ca:article/184The surface texture of aggregate particles was investigated based on the 3D model of surface generated from the measurements by optic microscope. New software MicroSYS was developed to determine the wrapping plane of 3D model of aggregate using the function called “Thin plate spline“. New parameter for evaluation of surface texture of aggregate particle was proposed as the volumetric difference between two planes (wrapping plane and aggregate surface). Applicability of this parameters was tested on two aggregate fractions (4/8 and 8/11) coming form 11 quarries in Slovakia. The tested aggregates differed from petrography point of view and ranged from soft to hard. The difference among the quarries and also between fractions of aggregate was found out. The better surface texture was observed for the finner fraction of aggregate. Simultaneously, the better results were determined in the case of aggregate produced from the ingeous intrusive or extrusive rocks comparing to the sedimentary carbonate rocks aggregate
34CrMo4 steel resistance against the SSC after controlled cooling process
Get PDFThe sulphide stress cracking corrosion resistance of 34CrMo4 steel after the accelerated cooling process under the Ar3 temperature was investigated. Two modes of heat treatment were applied to achieve homogeneous microstructure and at least partially eliminated segregation banding. First mode was based on the cooling up to the 420 °C on the air and subsequent cooling in the quenching bath. Second mode was similar except the temperature of cooling on the air, which was set up to the 460 °C. Afterward in both cases, the stress relief annealing was applied. Both modes of heat treatment resulted in the significantly banded microstructure based on the pearlite, ferrite and modified lower portion of accicular ferrite. The differences in mechanical properties of both cases of heat treatment were minimal. The SSC loading times to failure of both sets did not lead to important differences
Microstructural changes of AISI 316L due to structural sensitization and its influence on the fatigue properties
Get PDFMechanical and fatigue properties of material are dependent on its microstructure. The microstructure of AISI 316L stainless steel commonly used for the production of medical tools, equipment and implants can be easily influenced by its heat treatment. Microstructural changes and fatigue properties of AISI 316L stainless steel due to the heat treatment consisted of annealing at the temperature of 815°C with the dwell time of 500 hours were analyzed in the present paper. Precipitation of intermetallic phases and carbides was observed as a response of the material to the applied heat treatment. Small negative influence was observed in the case of fatigue region bellow 105 cycles; however the fatigue limit remains unchanged due to the structural sensitization
Fatigue Crack Propagation Under Variable Amplitude Loading Analyses Based on Plastic Energy Approach
Get PDFPlasticity effects at the crack tip had been recognized as “motor” of crack propagation, the growth of cracks is related to the existence of a crack tip plastic zone, whose formation and intensification is accompanied by energy dissipation. In the actual state of knowledge fatigue crack propagation is modeled using crack closure concept. The fatigue crack growth behavior under constant amplitude and variable amplitude loading of the aluminum alloy 2024 T351 are analyzed using in terms energy parameters. In the case of VAL (variable amplitude loading) tests, the evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading. A linear relationship between the crack growth rate and the hysteretic energy dissipated per block is obtained at high growth rates. For lower growth rates values, the relationship between crack growth rate and hysteretic energy dissipated per block can represented by a power law. In this paper, an analysis of fatigue crack propagation under variable amplitude loading based on energetic approach is proposed
The degradation of lining of rotary furnaces in the production of zinc oxide
Get PDFThis paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.
BEHAVIOR OF STEEL DP 600 UNDER DYNAMIC CONDITIONS
No full textDynamic tensile testing of sheet steels is becoming more important. Experimental dynamic tensile technique is depending on the strain rate. For experiments was used two testing method servo hydraulic and single bar method. Experiments was realized on steel grade DP 600. Steel were performed and evaluated static and dynamic tests. Was investigated substructure in static and dynamic loading conditions
Synthesis of a new 0.6PZS-0.4PLZT ceramics system, sintering and Microstructure properties characterization
Get PDFThe composition of 0.6PZS-0.4PLZT system was 0.6Pb (Zn1/3, Sb2/3) O3-0.4Pb0.98La0.02 (Zr0.48, Ti0.52) O3 were synthesized by a solid mixed-oxide solution method. The specific weight and porosity of the sintered component was measured from its mass and dimensions. The phase development and the lattice parameters of the sintered samples at 1050°C and 1200°C were analyzed and estimate by X-ray diffraction (XRD) (High score) and Celref software . The microstructure properties and morphology were characterized by scanning electron microscopy (SEM). The increasing in sintering temperature from 1050°C to 1200°C causes change for compound formation from Pb2Sb2O7 with cubic phase structure (FD3M) ,a= 10,4825°A; to another compound Zn2.3Sb0.67O4 with cubic phase structure (FD3M) ,a= 8,5354°A and slightly porous morphology
Improvement of the wear behaviour of highly-loaded components and tools by multi-combined surface treatment
Get PDFThis paper introduces a novel multi-combined surface treatment consisting of the individual treatments of plasma nitriding (PN), physical vapour deposition (PVD) and electron beam hardening (EBH). Using graded surface layers produced by such a combined surface treatment, it is possible to withstand the complex load conditions incurred by components and tools. It is shown, that the treatment sequences PN+EBH+PVD and EBH+PN+PVD are suitable for improving material properties. These multi-combined surface treatments lead to a significant improvement in load-supporting capacity. Critical load values of cohesive failure measured by scratch tests are tripled when compared to the individual treatment of PVD, and increased by at least 20% in comparison to the duplex treatments of EBH+PVD or PN+PVD. The metallurgical compatibility of the single treatments is essential for the success of combined treatments. Material-specific limitations are defined, which exclude failure due to crack initiation, the occurrence of retained austenite, and tempering effects. Based on the model wear-test assembly block-on-cylinder, it was proved, that the specific wear rate of multi-combined treated specimens is reduced about 20-50% while wear of counterpart components is decreased as well. The triplex surface heat treatment introduced opens up new prospects for highly-loaded components and tools
The impact of welding wire on the mechanical properties of welded joints
Get PDFThis paper presents results of the mechanical properties of Hardox 450 steel welded joints. These welded joints were made in accordance with welding procedure specifications (WPS), which was prepared and applied in the Wielton company. Fillers were provided by welding wires with two different diameters. The welding wire was G4Sil with diameter of 1.0 mm and 1.2 mm. The aim of this study was to examine whether the thickness of the welding wire has a direct effect on the properties of welded joints. Test specimens were made in similar parameters of the welding process. Then they were subjected to macroscopic research, tensile strength, impact strength and hardnes