Papers by Author: Wiktoria Ratuszek

Abstract: The work attempts substitution of very expensive, wear resistant Co-WC powders, that are commonly used in the production of sintered diamond tools, with cheap iron-base counterparts manufactured by ball milling. It has been shown that ball milled Fe-Ni and Fe-Mn powders can be consolidated to a virtually pore-free condition by hot pressing at 900°C. The as-consolidated materials are characterised by high hardness and resistance to 3-body abrasion.

Abstract: The textures of cold-rolled AISI 304 austenitic steel were the object of the investigations. The austenite steel was deformed by cold-rolling to 20, 40 and 70% reduction. A significant amount of martensite, formed due to the strain induced (γ®a’) transformation, was detected in the deformed structure by applying magnetic and X-ray diffraction methods. Texture analysis was performed on the basis of the orientation distribution functions (ODFs) calculated from the experimental pole figures. The texture measurements of both phases were conducted from the center layers of the cold-rolled strip. In the case of metastable austenite AISI 304 steel the texture development was very complex because three processes were proceded simultaneously during the cold-rolling, namely: plastic deformation of the austenitic g-phase, strain induced phase transformation γ®a’ and deformation of the formed a’-martensite. These processes resulted in the presence of two phases in the structure of the steel with a definite crystallographic relationship and orientation changes of both phases with increasing of the deformation. Thus, the resultant deformation texture of the investigated steels is described by the austenite and martensite texture components. The rolling texture of γ-phase describes mainly orientations from the fiber α =<110>║ND and the major components of the martensite deformation texture are orientations from the fibers α₁=<110>║RD and γ ={111}║ND.

Abstract: The aim of this work was the microstructure and texture analysis of a deformed via cold-rolling 24.5Mn-3.5Si-1.5Al-Ti-Nb TWIP/TRIP type steel. It was found, that during cold plastic deformation a phase transformation of austenite into martensite takes place. The transformation progress was confirmed by the microscopic investigations. The texture of austenite is characterized by a limited α₁=||RD fibre and the γ=||ND fibre. The texture of austenite changed with increasing deformation rate. In the texture of deformed austenite the strongest orientation is the {110} Goss orientation, which belongs to the α=||ND orientation fibre. During cold plastic deformation γ→ε and γ→ε→α’ phase transformations as well as the deformation of γ, ε and α’ phases are taking place in the steel. The formed ε phase (hexagonal structure) also possesses a distinct texture.

Abstract: This paper presents the results of the texture investigation in the hexagonal phase and the body-centered cubic  phase of the Ti6Al4V alloy hot-deformed by forging. Forging was performed at two different temperatures on the occurrence of the single  and in the two-phase  +  state. It was found that after deformation both  and  phases are textured and their textures strongly depends on deformation temperature.

Abstract: The research was carried out on 26Mn-3Si-3Al steel having a low value of SFE. After casting, steel was forged and hot-rolled at the temperatures within the range of from 1200°C to 900. Next, the steel was cold rolled until the deformation of 66% was obtained. Upon the basis of X-ray examination and the observations of microstructures, it was found out that during cold rolling mechanical twinning and the martensitic transformation of austenite in hcp-ε martensite occurred. The crystallographic texture of the γ phase (austenite) and ε phase (martensite) was also examined.

Abstract: The present work concerns the precipitation process of the sigma phase in the ferritic-austenitic stainless steel of duplex type SAF 2205. After the preliminary thermo-mechanical treatment, the steel was subjected to cold rolling up to 85% of reduction and subsequent annealing in the temperature range 650÷950°C for various times. Significant structural changes were observed in the course of annealing treatment affecting the formation of the ferrite and austenite texture. The development of annealing textures resulted from recovery and recrystallization processes in both component phases and the precipitation of the sigma phase. X-ray investigations included the phase analysis, measurements of pole figures for case of each phase, austenite and ferrite. Microstructure of analysis was conducted by means of optical microscopy. The microstructure and texture of duplex type steel after annealing result from the precipitation process of sigma phase, depend on the temperatures and time of annealing.

Abstract: The present research is a part of project which concerns a deformation behavior of duplex type ferritic-austenitic stainless steels. This paper focuses on the examination of ferrite and austenite textures formed upon thermo-mechanical treatment and deformation textures developed during cold-rolling of super-duplex stainless steel sheet. The character and stability of the textures observed in both phases over a wide deformation range are the result of two-phase morphology formed upon hot- and subsequent cold-rolling. The specific band-like morphology of the ferrite-austenite structure creates different conditions for plastic deformation due to the interaction of both phases and considerably constrained lattice rotations. That is why the processes governing the texture formation in duplex steels are supposed to change in comparison to single phase steels affecting final rolling textures of ferrite and austenite.

Abstract: Influence of the electrodepositing parameters e.g. applied electric current as variable on texture formation and on mechanical properties of copper thin films was studied. Experiment was done for copper deposition from sulphate bath under galvanostatic and pulse current. It was found that copper layers exhibits different texture depending on applied current conditions during electrodepositing process. Pulse and direct current conditions leads to different texture of electrodeposited copper. Texture of electrodeposited copper coatings and mechanical properties could be correlated. It was found that, texture indexes although are not complex information about texture could be used for analysis of such correlation in technological process.

Abstract: The present examination concerns a comparison of rolling texture development in two stainless steels of duplex type with different intensities of ferrite and austenite initial textures after a preliminary treatment, namely; clearly defined strong textures of both phases in one steel and nearly random textures in the case of the second one. Essentially the constituent phases in both duplex steels tend to develop the rolling textures comparable with those in single phase steels. However, the final textures display certain differences in comparison to the typical ferrite and austenite rolling textures. In both duplex steels the formation and character of the final deformation textures is strongly influenced by the band-like morphology of the ferrite-austenite structure and the process of texture formation proceeds in different way depending on the initial orientation distribution.

Abstract: The non-destructive structure characterisation of surface layers for various kinds of ball bearings can be a powerful method in surface characterization and in quality control. The ball bearings were made of 100Cr6 steel and they were superfinished and mechanically burnished. An application of classical X-ray diffraction sin2ψ method and classical Bragg-Brentano diffraction geometry in these kinds of surface examinations make some problems in term of X-ray real depth of penetration. An application of methods based on grazing angle X-ray diffraction geometry, made possible to get real value of residual macro-stresses, retained austenite and additionally could be suitable in estimation of their gradient-like distribution versus depth under surface. An application of this geometry to X-ray diffraction phase analysis enabled to get phase contents versus thickness under surface in non-destructive way as well. The results are not infected by gradient-like distribution. The X-ray quantitative phase analysis was used to establish volume fraction of transformed retained austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in ball bearings and following measurements of residual stresses were curried out as well. The mechanical burnishing of ball bearings caused big compressive residual stresses about – 1000 MPa and phase transformation of austenite in thin surface layer. These factors can influence on properties of following exploitation and durability.