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R. Bogucki and S.M. Pytel

Abstract

The results of mechanical properties and microstructure observation of low carbon copper bearing steel with high addition of molybdenum are presented in this paper. This steels were characterized by contents of molybdenum in the range from 1% to 3% wt. After the thermo -mechanical processing the steels were subsequently quenched and tempered at different temperatures (500-800 °C) for 1h. The changes of mechanical properties as function of tempering temperature were typical for the steel with the copper addition. The sudden drop of impact resistance after tempering from 575 °C to 600 °C was caused probably by precipitates of Laves phase of type Fe2Mo.

Open access

R. Bogucki, K. Mosór and M. Nykiel

Abstract

The influence of heat treatment on the microstructure and mechanical properties was studied in the Ti-10V-2Fe-3Al titanium alloy for two heat treatment schemes (α + β) and β + (β + α), which resulted in different morphologies of the α phase. Scheme I resulted in the α-phase of globular morphology, whose volume fraction did not change much during annealing. Scheme II led to obtaining a needle-like α-phase, whose amount increased together with heating time. The phenomenon of stress-induced martensitic transformation was observed in the material with needle-like morphology annealed for 15 and 30 min. Longer times of annealing effected in the decay of that transformation, provided the volume fraction of α-phase exceeded 50%.

Open access

R. Bogucki, K. Sulikowska, M. Bieda, P. Ostachowski and K. Sztwiertnia

Analysis of the results of the microstructure and the mechanical properties change in AA1050 aluminum alloy of technical purity processed using ECAP (Equal Channel Angular Pressing) and KoBo deformation methods are presented in the paper.. ECAP process was performed according to Bc scheme in the range from 1 up to 10 passes. Changes of microstructure were analyzed using scanning electrone microscope equipped with electron backscattered diffraction (EBSD) system. Microstructure and fraction of high-angle grain boundaries in KoBo processed samples were similar to those observed in ECAP processed samples after four passes. The most significant microstructure refinement was observed in ECAP processed sample submitted to 10 passes. In ECAP method the systematic increase of mechanical properties was observed along with increase of deformation degree.

Open access

A. Jarzębska, R. Bogucki and M. Bieda

In order to investigate the influence of the deformation degree and aging time on the mechanical properties and microstructure of AA7050 alloy static tensile test, microhardness measurements, calorimetric analysis and observations of the microstructure in the transmission and scanning electron microscope were carried out. For study a series of cylindrical specimens with an initial diameter of about 3 mm were used. The samples were saturated at a temperature of 470° C for 1 hour and quenched in water. The samples were then subjected to deformation up to the three levels: 0%, 5% and 10%. Deformed samples was artificially aged at 120°C for 6 hours, 12 hours, 24 hours and 72 hours. The results showed that the increase in the degree of deformation caused an increase in yield strength and a decrease in ductility. The longer aging time influenced on an increase in tensile strength, yield stress and microhardness and a decrease in ductility. An analysis of the precipitates present in the material was conducted. The highest value of yield strength equal 538 MPa with elongation 9.2% were obtained for sample pre-strained to 10% and aged for 24 hours. The obtained results showed that prolongation in aging time and use of pre-strain were beneficial for precipitation processes courses, consequently, for optimal mechanical properties of alloy 7050.

Open access

P. Koprowski, R. Bogucki, M. Bieda, J. Kawałko and K. Sztwiertnia

Abstract

The annealing behavior of AA1050 aluminum alloy deformed by equal-channel angular pressing (ECAP) was studied experimentally. The material was subjected to extrusion through die with channels intersecting at an 90° angle. Samples were pressed for up to 8 passes using route BC, then cut into slices and subsequently annealed for 1 hour at temperatures from 100°C to 350°C. Hardness measurements were performed on each slice. Microstructure of material was analyzed in the longitudinal section by means of Electron Backscatter Diffraction system in a scanning electron microscope (EBSD/SEM). From the obtained sets of Kikuchi diffraction patterns orientation maps and Image Quality maps were determined. Grain size, disorientation distributions and crystallographic texture were also estimated. ECAP caused significant improvement of hardness, with stabilization after 4 passes. Refinement of microstructure was obtained with the increasing amount of passes. Material properties were stable during annealing at temperatures lower than 150°C. Annealing at higher temperatures caused a decrease in hardness corresponding to an increase of the grain size.