Institute of Non Ferrous Metals in Gliwice

Skawina, Poland

Institute of Non Ferrous Metals in Gliwice

Skawina, Poland
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Qarni M.J.,University of Strathclyde | Rosochowski A.,University of Strathclyde | Boczkal S.,Institute of Non Ferrous Metals in Gliwice
IOP Conference Series: Materials Science and Engineering | Year: 2017

The objective of the present study is to investigate the deformation behaviour of Ultrafine-grain (UFG) commercial purity Titanium (CP-Ti) at warm temperatures. Firstly, CP-Ti billets were processed through six passes of incremental equal channel angular pressing (I-ECAP) at 300° C using a die channel angle (Φ) of 120°. Uniaxial compression tests were then performed under isothermal conditions on cylindrical samples obtained from the UFG CP-Ti billets. A series of these tests were conducted at different temperatures of 400, 500 and 600 °C and at varying strain rates of 0.01, 0.1 and 1.0 s-1. In each test, the original height of the sample was deformed by ∼50% of its original value. The true stress-strain curves obtained, revealed that the flow stress was sensitive to both temperature and strain rate. In general, the flow stress was higher for lower temperatures and higher strain rates. For tests conducted at 400 and 500 °C, the flow stress quickly reaches a peak value, beyond which it exhibits a steady state response where there is no appreciable change in flow stress with increasing strain. The 600 °C tests however shows a strain hardening behaviour. Microstructure of the sample deformed at 600 °C and 0.01 s-1, exhibited significant grain growth. © Published under licence by IOP Publishing Ltd.


Qarni M.J.,University of Strathclyde | Sivaswamy G.,University of Strathclyde | Rosochowski A.,University of Strathclyde | Boczkal S.,Institute of Non Ferrous Metals in Gliwice
Materials Science and Engineering A | Year: 2017

This paper presents an investigation on the evolution of microstructure and deformation characteristics of commercial purity Titanium (CP-Ti) during incremental equal channel angular pressing (I-ECAP). CP-Ti grade 2 was subjected to six passes at 300 °C following route BC, using a die with channel angle of 120°. Electron backscatter diffraction (EBSD) technique was used to characterize the microstructure after first, second, fourth and sixth pass, in the flow and transverse plane of the samples. Texture development through subsequent processing was also investigated using pole figures in both planes. Following first pass, the grain boundary maps across both flow and transverse plane showed a high degree of heterogeneity in grain morphology with the presence of elongated and fine grains. Also, misorientation peaks associated with {101̅2} tensile twins and a small fraction of {112̅2} compressive twins were observed in the microstructure. After second pass, microstructure was further refined and the twinning activity was greatly reduced with no noticeable activity after the fourth pass. Remarkable grain refinement was achieved after sixth pass with majority of grains in the ultrafine grain (UFG) range and with a relatively homogenous microstructure. Continuous dynamic recrystallization (CDRX) has been observed during subsequent I-ECAP processing. It was seen that twinning alongside CDRX acted as a dominant grain refinement mechanism during the initial passes of I-ECAP process beyond which slip was dominant deformation behaviour. © 2017 The Authors


Sulima I.,Pedagogical University of Cracow | Boczkal S.,Institute of Non Ferrous Metals in Gliwice | Jaworska L.,Pedagogical University of Cracow
Materials Characterization | Year: 2016

Steel-8TiB2 composites were produced by two new sintering techniques, i.e. Spark Plasma Sintering (SPS) and High Pressure-High Temperature (HP-HT) sintering. This study discusses the impact of these sintering methods on the microstructure of steel composites reinforced with TiB2 particles. Scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS), X-ray diffraction, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were used to analyze the microstructure evolution in steel matrix composites. The results of microscopic examinations revealed a close relationship between the composite microstructure and the methods and conditions of sintering. Substantial differences were observed in the grain size of materials sintered by HP-HT and SPS. It has been demonstrated that the composites sintered by HP-HT tend to form a chromium-iron-nickel phase in the steel matrix. In contrast, the microstructure of the composites sintered by SPS is characterized by the presence of complex borides and chromium-iron phase. © 2016 Elsevier Inc.


Paclawski K.,AGH University of Science and Technology | Piwowonska J.,Institute of Non Ferrous Metals in Gliwice
Archives of Metallurgy and Materials | Year: 2014

In this work, spectrophotometric studies on the kinetics and mechanism of the reaction between [PtCl6]2- complex ions and sodium thiosulfate, in neutral (pH = 7) and alkaline (p = 12) solution, were carried out. Applying different conditions, the influence of initial concentrations of reductant and platinum(IV) complex ions as well as the influence of temperature and ionic strength on the rate constant, was experimentally determined. From the obtained results, the molecularity, the order and the value of enthalpy and entropy of activation of the reaction, were experimentally determined. It was found that in both cases the reduction reaction is relatively slow and in the studied conditions the second-order rate constant changes from 2.92·10-2 to 0.40 M-1·s-1 at pH = 7, and from 3.84·10-2 to 1.55 M-1 s-1 at pH = 12. Additionally, depending on the pH, different mechanism of the reaction is present. However, regardless on the studied system the only platinum(II) chloride complex ions are the final product of the redox reaction. © 2014, Committee of Metallurgy. All rights reserved.


Paclawski K.,AGH University of Science and Technology | Piwowonska J.,Institute of Non Ferrous Metals in Gliwice
Archives of Metallurgy and Materials | Year: 2014

In this work, spectrophotometric studies of the kinetics and mechanism of reaction between [PtCl6]2- complex ions and sodium thiosulfate, were carried out. The influence of different conditions, such as: initial concentrations of reductant and platinum(IV) complex ions, ionic strength, pH and temperature on the rate constant, was experimentally determined. From the obtained results, the molecularity of the first elementary step, value of the enthalpy and entropy of activation in Eyring equation as well as corresponding rate equation, were experimentally determined. It was found that the reaction is relatively slow and leads to the S, Pt and PtS colloids formation. The best conditions for solid phase formation containing Pt are at pH = 5. © 2014, Committee of Metallurgy. All rights reserved.


Gzyl M.,University of Strathclyde | Rosochowski A.,University of Strathclyde | Boczkal S.,Institute of Non Ferrous Metals in Gliwice | Olejnik L.,Warsaw University of Technology
Materials Science and Engineering A | Year: 2015

Mechanical properties of AZ31B magnesium alloy were modified in this work by various processing routes of incremental equal channel angular pressing (I-ECAP) followed by heat treatment. Possible strategies for improving ductility and strength of the alloy were investigated. Processing by routes A and BC showed that texture plays predominant role in controlling mechanical properties at room temperature. Four passes of I-ECAP by route C followed by annealing enhanced ductility up to 0.35 of true strain. It was found that tensile twinning was important in accommodating strain during tensile testing, which resulted in a very good hardening behaviour. The yield strength was improved to 300MPa by refining grain size to 0.8μm in I-ECAP at 150°C. The obtained structure and properties were shown to be stable up to 150°C. True strain at fracture was increased to 0.2 after annealing at 150°C without lowering strength. © 2015 The Authors.


Mitka M.,Institute of Non Ferrous Metals in Gliwice | Gawlik M.,Institute of Non Ferrous Metals in Gliwice | Bigaj M.,Institute of Non Ferrous Metals in Gliwice | Szymanski W.,Institute of Non Ferrous Metals in Gliwice
Key Engineering Materials | Year: 2014

The study relates to a process of continuous rotary extrusion (CRE), also known under the name of a Conform Process. This method is used more and more extensively for the plastic working of metals and alloys. In CRE, the feedstock is fed into a profiled groove on the rotating extrusion wheel and is pressed by the pressing wheel. The friction of the extruded material against the rotating wheel generates a force that is pushing the material into the deformation chamber followed by extrusion through the die orifice.The extrusion by CRE was performed on an MC-260 device supplied by Meltech-Confex and installed at IMN - OML for processing of the 6063 aluminium alloy. The feedstock was composed of annealed rods. Two parameters were controlled during extrusion: the temperature of the shoe (element of the housing pressing the extruded material to the wheel) and the speed of the driving wheel.The 6063 alloy was extruded using the wheel speed of 2, 5, 10 and 15 rpm and the shoe temperature of 90°C and 105°C.The extruded flat sections were examined visually for continuity and quality of the resulting surface. In the feedstock rod and in the extruded flat sections (before and after heat treatment), the microstructure and grains were examined by light microscopy. Mechanical properties were also determined (static tensile test and hardness measurement).The study shows how the structure and the mechanical properties of the extruded flat sections are changing depending on the extrusion parameters applied.From the 6063 alloy rods extruded by CRE, flat sections of satisfactory quality were obtained. It was found that CRE yields the highest mechanical properties combined with the correct structure and high surface quality when the feedstock is extruded with the wheel rotational speed of 10 rpm and the shoe temperature of 105°C. © (2015) Trans Tech Publications, Switzerland.


Szymanek M.,Institute of Non Ferrous Metals in Gliwice | Augustyn B.,Institute of Non Ferrous Metals in Gliwice | Szymanski W.,Institute of Non Ferrous Metals in Gliwice | Kapinos D.,Institute of Non Ferrous Metals in Gliwice
TMS Light Metals | Year: 2013

The purpose of this study was to produce by Rapid Solidification process an alloy with Si content exceeding 20%. An ultrafine grained alloy from the AlSi30Cul.5Mgl.2Nil.5Fe0.8 system in the form of strips has been fragmented and subjected to the process of consolidation. The paper presents the technological aspect of the process of casting, fragmentation and plastic consolidation of semi-products.


Gzyl M.,University of Strathclyde | Rosochowski A.,University of Strathclyde | Boczkal S.,Institute of Non Ferrous Metals in Gliwice | Qarni M.J.,University of Strathclyde
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2015

Magnesium alloys are very promising materials for weight-saving structural applications due to their low density, comparing to other metals and alloys currently used. However, they usually suffer from a limited formability at room temperature and low strength. In order to overcome those issues, processes of severe plastic deformation (SPD) can be utilized to improve mechanical properties, but processing parameters need to be selected with care to avoid fracture, very often observed for those alloys during forming. In the current work, the AZ31B magnesium alloy was subjected to SPD by incremental equal-channel angular pressing (I-ECAP) at temperatures varying from 398 K to 525 K (125 °C to 250 °C) to determine the window of allowable processing parameters. The effects of initial grain size and billet rotation scheme on the occurrence of fracture during I-ECAP were investigated. The initial grain size ranged from 1.5 to 40 µm and the I-ECAP routes tested were A, BC, and C. Microstructures of the processed billets were characterized before and after I-ECAP. It was found that a fine-grained and homogenous microstructure was required to avoid fracture at low temperatures. Strain localization arising from a stress relaxation within recrystallized regions, namely twins and fine-grained zones, was shown to be responsible for the generation of microcracks. Based on the I-ECAP experiments and available literature data for ECAP, a power law between the initial grain size and processing conditions, described by a Zener–Hollomon parameter, has been proposed. Finally, processing by various routes at 473 K (200 °C) revealed that route A was less prone to fracture than routes BC and C. © 2015, The Minerals, Metals & Materials Society and ASM International.


Gawlik M.,Institute of Non Ferrous Metals in Gliwice
Solid State Phenomena | Year: 2015

The study presents the results of microstructure examinations and phase identification of precipitates in AlMn alloys containing zirconium after heat treatment and rolling. Chemical composition in microareas was determined by Energy Dispersive Spectrometry (EDS) microanalysis performed in Scanning Electron Microscope (SEM-EDS) and Scanning Transmission Electron Microscope (STEM-EDS) modes. Phase identification was carried out using Electron Backscatter Diffraction (EBSD) method. Studies have shown that Al6Mn and α- Al17(Fe3.2Mn0.8)Si2 phases were formed in the melt. Microstructure examined by TEM showed the presence of finely dispersed spherical precipitates of zirconium. In the alloy with an addition of silicon and magnesium, numerous precipitates of an Mg2Si phase were also found. © (2015) Trans Tech Publications, Switzerland.

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