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1

Oxide layers on titanium obtained by anodizing in orthophosphoric acid

Wilk M., Klimek L.

Archives of Materials Science and Engineering

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2018

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Vol. 94, nr 1

11--17

EN

Purpose: Titanium is an essential material used in modern dentistry, mostly due to its tissue compatibility. However, there are another physicochemical assets, which can be harnessed. One of these is enhancing the bonding strength of titanium with another materials. In view of the advantageous effect of oxide layers on the bond with the ceramics, an attempt was made at creating oxide layers on samples of commercially pure titanium applied as the material for metal frameworks of prosthetic restorations. Design/methodology/approach: As the research material cylindrical wet grinded commercially pure titanium, Grade II samples were used. The samples were divided into three groups and underwent anodic oxidation in 1 M orthophosphoric acid, with the voltages: 120 V, 160 V, 200 V. After the anodizing process, the samples were subjected to the X-ray diffraction, analysis of the element distribution from the surface towards the inside of the materials using an optical spectrometer, finishing with the tests performed with a scanning microscope to determine the morphology of the obtained layers. Findings: Layers of 0.26 pm to 0.65 pm thick were achieved. The performed studies demonstrated that increasing reaction voltage contributes not only to thickening of the oxide layers but also influences to porosity. The layers obtained in the electrolyte which contained monomolar orthophosphoric acid consist of only one allotropic type of titanium oxide - anatase. The spectrometric tests showed that the content of titanium and oxygen in the layer is not constant, which proves that the formed layer does not have a strictly stoichiometric composition TiO2, but rather TiO2-x. Research limitations/implications: It is necessary to provide the optimal voltage directly related to the employed acid solution to preserve the usable thickness of oxide layers. Too thick (over 1 pm) coating may lead to exfoliating. Contrary, distinctly thin layers present fractures and decrements, accordingly do not veneer entire surface of titanium sample. Originality/value: Usually oxide layers obtained by anodic oxidation are examined paying special attention to tissue integration and usability in implantology. Following paper is focused on bonding titanium with dental ceramics to facilitate process of designing porcelain-fused-to-metal fixed dentures.

2

Semi-continuous caster for plate

Haga T., Miyazaki K.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 84, nr 2

58--67

EN

Purpose: Development of a semi-continuous caster that can cast a single plate and a clad plate of Al-40%Sn-1%Cu alloy used for sliding bearings. Design/methodology/approach: A semi-continuous caster to cast a single plate and a clad plate directly from molten metal was designed and assembled. The cast single plate has a thickness ranging from 10 mm to 30 mm, a width of 400 mm, and a length of 500 mm to 1,000 mm. The cast clad plate has a thickness ranging from 10 mm to 30 mm, a width of 50 mm, and a length of 300 mm. Findings: The semi-continuous caster successfully produced both a single plate and a clad plate of Al-40%Sn-1%Cu alloy. Influence of casting conditions on the properties of the plate, including the thickness, porosity, and surface quality were investigated in the single plate casting. The mixing and diffusion of the alloy elements at the interface was also investigated in the clad plate casting. Research limitations/implications: The cast Al-40%Sn-1%Cu alloy plate has not yet been tested as a sliding bearing material, so the efficacy of the material still requires investigation. Practical implications: The semi-continuous caster described in this paper enables the “small lot” production made from single and clad plates of aluminium alloy. Originality/value: Development of a semi-continuous caster that can cast both single and clad plates of aluminium alloy. Investigation of the relationship between the casting conditions and plate quality.

3

In situ-formed, low-cost, Al-Si nanocomposite materials

Guba P., Gesing A.J., Sokolowski J., Conle A., Sobiesiak A., Das S. K.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 84, nr 1

5--22

EN

Aluminum-Silicon (Al-Si) alloys are the “bread-and-butter” of the aluminum foundry industry being cast at an annual rate of over 2 million tonnes/year in North America for use mainly in transportation. Coarse microstructure of these alloys limits their specific mechanical properties and consequently their potential for vehicle lightweighting. Purpose: We report on a new family of cast Al-Si alloys producing in-situ formed nanocomposites of up to 25 vol.% ultrafine equiaxed silicon particles in Al alloy matrix which can be ductile, or reinforced by nano-scale spinodal constituents. Design/methodology/approach: The hypereutectic Al-Si-X alloy (A390) was melted, solidified and cooled on the novel High Pressure Die Casting Universal Metallurgical Simulator and Analyser Technology Platform (HPDC UMSA) at specific process parameters. The HPDC cast samples consecutively were solution treated and artificially aged to spheroidize the Si and to dissolve the intermetallics in Al(SS) and to re-precipitate them in the solid state as nano-sized spinodal structures. The heat treatment was performed using the High Temperature UMSA Technology Platform. Findings: The nano scale structure of these new materials gives them significantly improved strength, hardness, and wear resistance while retaining adequate toughness and ductility for applications in the transportation applications. Research limitations/implications: Desired composite nanostructures have been produced and characterized in-situ in small laboratory test samples. Practical implications: These new materials can be produced by conventional casting technologies such as continuous strip casting, or high-pressure die-casting from conventional low-cost Al-Si melts. Originality/value: These materials can be produced with a significantly higher volume fraction of ultrafine Si dispersoids than has been done to date in in-situ formed materials, while retaining and improving the density-specific mechanical properties.

4

Effect of combinative cooled addition of strontium and aluminium on mechanical properties AlSi12 alloy

Lipiński T.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 83, nr 1

5--11

EN

Purpose: The study was to determine the mechanical properties of hypo-eutectic silumin AlSi12 modified with Sr or Al-Sr alloy slow or fast cooled and in the form of a strip or powder. Design/methodology/approach: The experiment performed on EN AB-AlSi12 hypoeutectic alloy. Aluminium and strontium was melted and next fast cooled to room temperature or cooled on a metal plate at rates about 200°C/s. This enabled to produce a different components, which were powdered immediately before adding to the alloy or used as a strip. The scope of this paper was to verify the cooling effect of Sr-Al modifiers and its form (powder or strip) on the microstructure and mechanical properties the AlSi12 alloy. Findings: The use of fast cooled Al-Sr alloy in the modification process and/or powdered alloy contributed to a further increase mechanical properties AlSi12 alloy. Research limitations/implications: The modification alloys with fast cooled powdered modifier are attractive for future research. Practical implications: Widely presented books and research papers on the silumin treatment give not a lot of contents on the effect treatment fast cooled alloy in the form of a strip or powder. Originality/value: The original value of the paper is comparison Sr and Al-Sr alloy modifiers slow and fast cooled and used as a powder or strip.

5

The effect of chemical composition on microstructure and properties of TRIP steels

Kučerová L., Bystrianský M.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 77, nr 1

5--12

EN

Purpose: Various alloying strategies can be used to produce advanced high strength steels and this work offers comparison of results achieved for four different low alloyed steels with 0.2-0.4 %C, 0.5-2 %Si, 0.6-1.5 %Mn, 0.03-0.06 %Nb and with 0.8-1.33 %Cr. Microstructures obtained by two methods of thermo-mechanical treatment were analysed for each steel and compared with theoretical predictions of TTT (time temperature transformation) diagrams calculated by JMatPro. Design/methodology/approach: Thermo-mechanical treatment of all steels was carried out at thermo-mechanical simulator. Resulting microstructures were analyses by the means of scanning electron microscopy, mechanical properties were measured by tensile test. Findings: It was found out that microstructures typical for TRIP (transformation induced plasticity) steels can be obtained easily for low carbon steels alloyed by silicon or aluminium-silicon and micro-alloyed by niobium. Chromium addition influenced austenite decomposition causing intensive pearlite formation in low carbon steel and predominantly martensitic microstructure in middle carbon steel. These microstructures were not in agreement with calculated TTT diagrams. Research limitations/implications: To obtain ferritic-bainitic microstructure with retained austenite typical for TRIP steels, chromium alloyed steels require substantial optimisation of processing parameters. This issue should be addressed in future work. Practical implications: JMatPro software is well equipped to calculate TTT diagrams for steels alloyed by manganese, silicon and niobium, however further chromium addition changed behaviour of the steel in a way that the software was not able to predict. Originality/value: Obtained results could be useful for consideration of chemical composition of low alloyed steels with respect to resulting microstructures and properties.

6

Influence of niobium on the structure and properties of the matrix of high-speed steel with nickel

Pacyna J., Dziurka R., Grudzień M.

Inżynieria Materiałowa

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2016

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Vol. 37, nr 6

335--340

EN

The following paper investigates two model alloys simulating the quenched matrix of high-speed steels with an addition of 1.5% Ni, which was enriched with 1% and 2% of Nb to increase abrasion resistance. Based on the alloys’ composition comprising of W, Mo, V and Cr, the simulations of the quenched matrix of the high-speed steels indicate sufficiently high hardenability. The purpose of increasing the nickel content in the composition of such alloys was to increase their crack resistance, whereas the addition of the strongly carbide-forming niobium in amounts of 1% and 2%, balanced by an additional carbon content, was aimed at increasing the abrasion resistance of these steels. The authors of the above mentioned chemical composition concept expect that these types of alloys will be used in the production of tools (rolls) designed for the rolling of metallurgical products which are difficult to produce (flat bars, channel bars and tee bars). The quenching temperature of both alloys was optimised on the base of the so called quenching series. The accurate CCT diagrams and the tempering series for revealing the secondary hardness effect were also performed for these alloys. All investigation stages were accurately documented by metallographic tests.

PL

W pracy postanowiono wznowić badania na osnowie zahartowanej stali szybkotnącej, jednakże jej skład uzupełniono dodatkiem około 1,5% Ni oraz dodatkami odpowiednio około 1% i 2% Nb. Dodatki niobu, jeżeli tylko zostaną zbilansowane odpowiednimi dodatkami węgla, powinny dzięki utworzeniu stabilnych węglików Nb4C3 zwiększyć odporność na ścieranie stopu, a dodatki niklu powinny zwiększyć jego odporność na pękanie. Takie postępowanie powinno umożliwić uzyskanie materiału narzędziowego odpornego na ścieranie oraz odpornego na pękanie o właściwościach zahartowanej osnowy stali szybkotnących. Autorzy składu chemicznego nowych stopów i ich koncepcji spodziewają się, że będą one stosowane do wytwarzania narzędzi (walców) przeznaczonych do walcowania produktów hutniczych, które są trudne do wytworzenia (płaskowników, ceowników oraz teowników).

7

The influence of the distribution of nonmetalic inclusion on the fatigue strength coefficient of high purity steels

Lipiński T.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 69, nr 1

18--25

EN

Purpose: In this study, attempts were made to analyze the impact of impurities with various diameters and spacing between non-metalic inclusion λ on fatigue strength coefficient k determined under rotary bending fatigue conditions zgo of high purity steels produced in an industrial plant. Design/methodology/approach: The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between submicroscopic impurities. Findings: Equations for calculating the fatigue strength coefficient at each tempering temperature and a general equation for all tempering temperatures were proposed. Equations for estimating the fatigue strength coefficient based on the relative volume of submicroscopic non-metallic inclusions were also presented. The relationship between the fatigue strength and hardness of high-grade steel vs. the quotient of the diameter of impurities and the spacing between impurities, and the fatigue strength and hardness of steel vs. the relative volume of non-metallic impurities were determined. Practical implications: The proposed linear regression equations supported the determination of fatigue strength coefficient k and bending fatigue strength as a function of hardness taking into account impurities. Originality/value: The proposed equations contributes to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metalic inclusion on fatigue strength.

8

Structural stability of nickel superalloy IN740H after ageing in 750°C

Hernas A., Kościelniak B., Bednarczyk I.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 69, nr 1

5--9

EN

Purpose: Constant demand for electric energy as well as legal and ecological conditions of the country motivate the construction of advanced ultra-supercritical AUSC power units. Increase of the steam parameters to about 700°C and pressure to over 30 MPa requires the application of modern nickel superalloys, which need to be characterized by structural stability at high temperature. The paper presents the results of analysis of structural changes of IN740H superalloy after ageing at 750°C. Design/methodology/approach: Alloy specimens were aged at 750°C for 100 h, 500 h and 1000 h. Evaluation of structure was carried out with the use of light, scanning and scanning-transmission microscopy techniques as well as microanalysis of chemical composition with the use of X-ray spectrometer with energy dispersion (EDS). Findings: The microstructure analyses applying light and electron microscopy revealed the precipitation processes occurring in the structure of IN740H alloy. It has been shown the changes of morphology of γ’ phases and carbides due to heat treatment. Practical implications: The research carried out enabled to know the structural changes of IN740H during ageing at high temperature, which are determined the mechanical and physicochemical properties of alloy. Originality/value: Applied quantity and quality methodology of testing and achieved results of tests broaden the state of knowledge which refers to superalloys of nickel which are recommended to be applied in construction of super-ultra-supercritical boilers (AUSC).

9

Microstructural banding in titanium alloys

Krawczyk J., Dąbrowski R., Łukaszek-Sołek A., Frocisz Ł., Górecki K., Cios G., Śleboda T., Kopyściański M., Bała P.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 72, nr 1

5--13

EN

Purpose of this paper was to investigate the phenomenon of microstructural banding in three titanium alloys: Ti-6Al-4V, Ti-10V-2Fe-3Al and Ti-3Al-8V-6Cr-4Mo-4Zr. Design/methodology/approach: The microstructure of the investigated materials in as-delivered condition was characterized. Compression tests were performed on Gleeble thermomechanical simulator to investigate banding phenomena occurring in the microstructure of each studied alloy. Moreover, banding phenomena was also investigated in the case of forging obtained from Ti-6Al-4V alloy. Heat treatment conditions allowing to reduce banding in the microstructure of the investigated alloys were also determined. Findings: Thermomechanical processing leading to dynamic recrystallization in the investigated alloys restricts the formation of bands in their microstructure. Homogenizing treatment can also reduce banding in such alloys. Research limitations/implications: Future research should concern the investigations of grain size in the recrystallized alloys and in the alloys subjected to homogenizing heat treatment. Practical implications: The results of this research should allow obtaining homogenous microstructure in titanium alloys studied in this paper. Originality/value: The range of the temperature and strain rate for dynamic recrystallization restricting banding in the microstructure in the investigated alloys was determined. In the case of Ti-3Al-8V-6Cr-4Mo-4Zr alloy the range of the temperature and time of annealing leading to homogenization of the material was identified.

10

A comparative study of Ti-Al and Ti-Nb alloys for advanced technological applications

Peter I., Rosso M., Castella C.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 73, nr 2

199--205

EN

Purpose: of this paper is to compare some properties of Ti-Al and Ti-Nb alloys to investigate on the possibility to jointly employed them industrially. Ti-Al alloys have been proposed because they present challenging characteristics for high temperature purposes and β type Ti-Nb alloy has specific mechanical properties at room temperature. Ti-Al alloys are very attractive materials and represent one of the most important materials employed for aero jet engines. The most promising alloy belonging to the above mentioned classes are predominantly based on simultaneously presence of two phases, namely γ-TiAl (gamma titanium aluminides) and α2-Ti3Al both with a fully lamellar microstructure and could replace Ni-based superalloys in some high temperature applications in aerospace and automotive industries. The most important advantages of such alloys compared to some superalloys consist in their low density correlated to their superior efficiency in service and reduced gas emission. Design/methodology/approach: The Ti-Al alloy have been produced by gravity casting, using a vibrating furnace, while the Ti-Nb alloy samples have been realized by the cold crucible levitation melting (CCLM) casting technology. Microstructural and mechanical characterization have been performed. Findings: The microstructural analysis for the Ti-Al alloy reveals a fully-lamellar microstructure with alternate plates of α2-(Ti3Al) and γ-(TiAl) plates. The grains have an average size of about 200 μm. For the Ti-Nb based alloy only a β mono-phase has been detected. This alloy has a equiaxed microstructure with an average grain dimension of about 170 μm. The Ti-Nb alloy presents a high mechanical strength while on the contrary that of the Ti-Al has been deleteriously affected by the presence of large gas porosities. Superior hardness values have been reached with Ti-Al alloy, due to the presence of hard γ-TiAl. Practical implications: The most important implication is related to the transfer toward the proper choice of the correct parameters during manufacturing. Originality/value: Investigation on the influence of the elemental composition enriched by other elements and casting processes on the defect development, the microstructural characteristics and on the mechanical behaviour of the alloys.

11

Phase transformations in the precipitation hardened cast steel

Pacyna J., Dziurka R., Grudzień M.

Archives of Materials Science and Engineering

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2015

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Vol. 73, nr 2

62--68

EN

Purpose: The microstructure of the new ledeburitic, tool cast steel of the precipitation hardened matrix was designed. The concept of this microstructure was based on the microstructure of the steel-bonded carbides [1,2], in which a skeleton is built of sintered carbides. This skeleton is produced by the powder metallurgy methods and then filled with melted steel of the selected chemical composition. Design/methodology/approach: The new cast steel of the structure analogous to the steel-bonded carbides was conventionally melted in a furnace, however with omitting pressing and sintering operations of the powder metallurgy. The carbides skeleton in the new cast steel is formed by carbides of the MC type forming jointly ledeburite and its matrix constitutes steel hardened by precipitates of intermetallic compounds. This new material will be destined for tools of a moderate hardness (approximately 40 HRC), high abrasion resistance and high strength. Findings: Utilising hard carbides forming by elements of VB group of the Mendeleev’s table it is possible to design the tool material similar to the steel-bonded carbide of the selected matrix composition and primary carbides of MC type. Research limitations/implications: The chemical composition the matrix of designed material decides on its hardness and strength, the MC type carbides decide on the abrasion resistance and if they occur in the eutectic form they decide on a rather low fracture toughness. Therefore efforts should be undertaken to have non-ledeburitic materials. Practical implications: As a result of these investigations a new precipitation hardened cast steel have been worked out and a possibility of its industry applied was shown. Originality/value: The results of investigations of phase transformations in the new cast steel at its heating and cooling from the austenite range, are presented in the hereby paper.

12

Strength properties of the low-melting-point alloys

Wierzbicki Ł.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 67, nr 1

26--31

EN

Purpose: The aim of this paper was to determine the strength and elasticity of low melting point alloys. In particular, the laboratory tests were observed to check the shape of the compression curve. This is a result of recrystallization. Design/methodology/approach: The strength and stiffness of the low melting point alloys was found. The unusual shape of the compression curve was observed. In order to determine if it is the result of crystallization, the samples were cooled in the liquid nitrogen. In the next step another attempt will be perform to the compression. Findings: The results of the compression tests and their analysis are presented. Research limitations/implications: Presented research was limited to alloys in the form of small samples. The developed technology of this type of preparation of this type alloys is limited to small volumes because the melts are small and expensive. Practical implications: The low melting point alloys have many possible applications. First of all they are materials with higher thermal conductivity and electrical conductivity. Conducted research programme showed that these materials exhibit also good the mechanical properties. Originality/value: Carrying out of the experiment that explaining of the shape of the compression curve for low-melting-points alloys. This experiment may be have a high educational value for the study. This experiment can have high an educational value for the science.

13

The phase transformations during continuous cooling of Ti6Al7Nb alloy from the two-phase α+β range

Dąbrowski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 59, nr 1

7--12

EN

Purpose: The phase transformations during continuous cooling from the two-phase α+β range in Ti6Al7Nb alloy has been determined. Design/methodology/approach: The phase transformations during continuous cooling of investigated alloy was elaborated using an L78 R.I.T.A dilatometer of the German Linseis Company. The microstructure of investigated alloy cooled from the two-phase α+β range was examinated by a light microscope Axiovert 200MAT. The measurements of hardness were performed with the Vickers HPO 250 apparatus. Findings: The relationship between cooling rate and microstructure morphology, hardness as well as dilatation effects has been determined. Research limitations/implications: The results will be used for the interpretation of phase transformations occurring at continuous cooling and at tempering from as-quenched state of the investigated alloy. Currently, the investigations of the kinetics phase transformation at continuous heating from as-quenched state will help to performed the Continuous-Heating-Transformation diagrams (CHT). These diagrams show the possibility of the regulation of the progress of successive (intermediate) transformations at tempering and thus influence the final alloy properties, including their hardness and fracture toughness. It is expected that the determination of final mechanical properties by means of regulating the progress of successive transformations occurring during heating from the as-quenched state is possible also in the Ti6Al7Nb alloy. Practical implications: The obtained results will be applied for the optimization of the heat treatment technology and for achieving the required mechanical properties of the Ti6Al7Nb alloy. Originality/value: The obtained results, supported in the future by additional cooling curves, will be used for the development of the original, full CCT diagram of the Ti6Al7Nb alloy cooled continuously from the two-phase α+β range.

14

Microstructure investigations of cast Zn-Al alloys

Krupińska B., Rdzawski Z., Krupiński M., Labisz K.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 1

12--19

EN

Purpose: The goal of he presented investigations was to evaluate to possibility of application of popular modifiers for chosen types of zinc alloys. The special aim of this work is to determine the influence of alloy modification on the crystallisation kinetics and microstructure of the cast zinc alloy. This research work presents also the investigation results of derivative thermoanalysis performed using the UMSA device. The material used for investigation was the ZnAl8Cu1 alloy. Design/methodology/approach: For phase determination there were used electron microscope techniques like SAD diffraction investigations which were carried out on the 200 kV transmission electron microscope. The UMSA (Universal Metallurgical Simulator and Analyser) device allows it to determine the specific melting process, influence of the cooling rate on the crystallization of phases and eutectics of the investigated alloys. Cooling rate influences the microstructure and properties of the investigated zinc cast alloys. Findings: Change of the crystallization kinetics allows it to produce materials with improved properties, which are obtained by: microstructure refinement, reduction or elimination of segregation. Research limitations/implications: The material was examined metallographically and analysed qualitatively using light and scanning electron microscope as well as the area mapping and point-wise EDS microanalysis. The performed investigation are discussed for the reason of an possible improvement of thermal and structural properties of the alloy. Practical implications: The investigated material can find its use in the foundry industry; an improvement of component quality depends mainly on better control over the production parameters. Originality/value: Investigations concerning the development of optimal chemical composition and production method of zinc-aluminium alloys with selected rare earth metals with improved properties compared to elements made of alloys with appliance of traditional methods, will contribute to a better understanding of the mechanisms influencing the improvement of functional properties of the new.

15

Microstructure investigations of cast Zn-Al alloys

Krupińska B., Rdzawski Z., Krupiński M., Labisz K.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 60, nr 1

15--22

EN

Purpose: The goal of the presented investigations was to evaluate to possibility of application of popular modifiers for chosen types of zinc alloys. The special aim of this work is to determine the influence of alloy modification on the crystallisation kinetics and microstructure of the cast zinc alloy. This research work presents also the investigation results of derivative thermoanalysis performed using the UMSA device. The material used for investigation was the ZnAl8Cu1 alloy. Design/methodology/approach: For phase determination there were used electron microscope techniques like SAD diffraction investigations which were carried out on the 200 kV transmission electron microscope. The UMSA (Universal Metallurgical Simulator and Analyser) device allows it to determine the specific melting process, influence of the cooling rate on the crystallization of phases and eutectics of the investigated alloys. Cooling rate influences the microstructure and properties of the investigated zinc cast alloys. Findings: Change of the crystallization kinetics allows it to produce materials with improved properties, which are obtained by: microstructure refinement, reduction or elimination of segregation. Research limitations/implications: The material was examined metallographically and analysed qualitatively using light and scanning electron microscope as well as the area mapping and point-wise EDS microanalysis. The performed investigation are discussed for the reason of an possible improvement of thermal and structural properties of the alloy. Practical implications: The investigated material can find its use in the foundry industry; an improvement of component quality depends mainly on better control over the production parameters Originality/value: Investigations concerning the development of optimal chemical composition and production method of zinc-aluminium alloys with selected rare earth metals with improved properties compared to elements made of alloys with appliance of traditional methods, will contribute to a better understanding of the mechanisms influencing the improvement of functional properties of the new.

16

Designing and controlling the microstructure of 37MnNiMo6-4-3 hypoeutectoid steel after continuous cooling

Rożniata E.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 58, nr 1

24--30

EN

Purpose: Present work corresponds to the research on the kinetic of phase transformation of undercooled austenite of 37MnNiMo6-4-3 hypoeutctoid steel. The kinetic of phase transformation of under cooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation). Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described. Design/methodology/approach: The austenitising temperature was defined in a standard way i. e. 30-50°C higher than Ac3 temperature for hypoeutectoid steels. The technology of full annealing was proposed for the iron based alloy. The CCT diagram was made on the grounds of dilatograms recorded for samples cooled with various rates. The microstructure of each dilatometric sample was photographed after its cooling to the room temperature and the sample hardness was measured. Also EDS analysis was performed using scanning microscope. Findings: The test material has been hypoeutectoid steel. These steels represent a groups of alloy steels for quenching and tempering. The microstructure of test 37MnNiMo6-4-3 hypoeutectoid steel on CCT diagram changes depending on the cooling rate. Research limitations/implications: The new hypoeutectoid steel and new CCT diagram. Practical implications: The paper contains a description of one from a group of iron based model alloys with 0.35-0.40% carbon content. According to PN-EN 10027 standard this steel should have a symbol 37MnNiMo6-4-3. Originality/value: The new hypoeutectoid steel (Mn-Ni-Mo iron based model alloy).

17

The mathematical model of the mean flow stress for MgAl3Zn1Mn magnesium alloy

Cizek L., Legerski M., Rusz S., Tański T., Hadasik E., Salajka M.

Archives of Materials Science and Engineering

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2013

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Vol. 61, nr 1

5--12

EN

Purpose: The presented paper deals with method for determination of mean flow stress (MFS) which contributes to better knowledge of forming processes of hot formed magnesium alloys. Design/methodology/approach: An experiment leading to obtaining the model of the mean flow stress (MFS) of magnesium alloy AZ31 was realized in laboratory rolling mill. It resulted from mathematical and statistical processing of MFS values that these could be described by a simple function of just two independent variables – temperature (200 to 450°C) and equivalent height strain (approx. 0.2 to 0.7). The methods of the light microscopy for metallographic analyses were used. Findings: The increasing strain resulted in decreasing deformation resistance. The effect of equivalent strain rate (approx. 10-80 1/s) was negligible. The model describes the given relationship with good accuracy; a relative error of calculated MFS values does not exceed ±10%. Research limitations/implications: In future work an important relation between the MFS, the Zener-Hollomon parameter and the grain size will be determined. A significant influence of the deformation temperature on the average grain size after recrystallization was identified, while observing lower sensitivity of this parameter to an increased strain rate. Practical implications: The results of structural studies along with the devised thermomechanical model will be used to design the foundations of rolling technology for this group of alloys. The results of this paper are determined for research workers deal by development new exploitations of magnesium alloys. Originality/value: These results describe complex evaluation of properties magnesium alloys namely for determination of the values of mean flow stress (MFS) which contributes to better knowledge of forming processes of hot formed magnesium alloys and explain the structure developed used magnesium alloys after forming.

18

Effect of heating rate on the phase transformations during tempering of low carbon Cr-Mn-Mo alloy steel

Dziurka R., Pacyna J., Tokarski T.

Archives of Materials Science and Engineering

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2013

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Vol. 63, nr 1

13--18

EN

Purpose: The effect of heating rate to the tempering temperature on the microstructure and properties of lath martensite tempered at a various temperatures was studied in literature from point of the cemntite precipitations view. It has been shown that cementite dispersion is finer and more uniform in the rapidly heated and tempered than in the slowly heated and tempered specimen. Aim of this work is to investigate the effect of heating rate on the phase transformations during tempering. Design/methodology/approach: The investigations of phase transformations during tempering of the low carbon steel were made on the grounds of dilatometric curves recorded during heating from as-quenched state. Heating to isothermal holding at 350°C was made with two different heating rates (100°C/s and 5°C/s) and was performed by use of the L78 R.I.T.A. dilatometer made by Linseis. The investigations of phase transformations during continuous heating from as-quenched state were performed by use of the DT 1000 dilatometer made by Adamel. Findings: It is possible to reduce probability of the occurrence of some phase transformations in favor of other. The difference in advancement of the various phase transformations can effects on various mechanical properties of the steels. Research limitations/implications: The effect of the heating rates (100°C/s and 5°C/s) during heating from as-quenched state on the phase transformations during isothermal holding at 350°C was submitted. It is expected to carry out further research on the effect of the heating rate on the phase transformations during isothermal holding at different temperatures and their effects on mechanical properties. Practical implications: The obtained information may be used to design new technologies of steels tempering. Originality/value: The new point of view on the tempering of the steels can be assumed.

19

The influence of saliva and its substitutes on corrosion of some implant alloys

Andrysewicz E.

Acta Mechanica et Automatica

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2013

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Vol. 7, no. 2

69--74

EN

The purpose of this paper is evaluation of the influence of human saliva and its substitutes on the corrosion re sistance of some implant alloys used in stomatology, which included: austenitic steel (316L), titanium alloy (Ti6Al4V), and cobalt alloy (CoCrMo). Corrosion studies were conducted by means of the potentiodynamic method with the application of the VoltaLab 21 kit with VoltaMaster 4 software. The reference electrode was a saturated calomel electrode (SCE), whereas the counter electrode was a platinum electrode. The results of conducted studies indicate an increased current density in the passive range on potentiodynamic curves of studied alloys in the envi- ronment of human saliva, and also in a commercial saliva solution – Mucinox. On the basis of conducted corrosion studies, it can be stated that in terms of corrosion resistance the developed saliva substitutes may constitute competitive solutions to commercial saliva substitutes. The prepared substitutes should be studied further from the perspective of practical application for patients. The original value of the paper is a proposition of new saliva substitutes.

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Thermal stability of protective coatings produced on nickel based superalloy

Pytel M., Góral M., Motyka M., Miziniak T

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 51, nr 2

67--77

EN

Purpose: In this paper the results of high temperature cyclic oxidation tests of the protective diffusion coatings were presented. One of the main purposes of this work was to produce three different types of protective coatings by three different methods, i.e. slurry method, vapour phase aluminizing (VPA) and chemical vapour deposition (CVD), applied on nickel based Rene 80 superalloy substrate. Design/methodology/approach: The high temperature cyclic oxidation tests were carried out in 23h cycles at constant temperature 1100°C using Carbolite CWF 1300 chamber furnace. The samples were removed outside and were weighted after each cycle. The microstructure investigations of all kinds of the coatings were conducted by the use of light microscope (Nikon Epiphot 300) and a scanning electron microscope (Hitachi S-3400N). In the analysis influence of each method have been taken into consideration, i.e. especially influence of the kind of process on microstructure, coating thickness, chemical composition, first of all aluminium content (in outer β-NiAl layer so-called additive layer, diffusion layer and substrate). For the chemical composition examination x-ray energy dispersive (EDS) method was applied using Thermo equipment. Findings: It was found that the best high cyclic oxidation resistance of coating was obtained using CVD method (the maximal increase of samples weight after 28th cycle was observed, whereas in case of the slurry sample after 3rd and VPA after 5th). Research limitations/implications: The research results will be used in the future in order to increase coating thickness, aluminium content and to produce Pt, Pd, Zr, Hf and Si modified aluminide coatings. Practical implications: The CVD method will be used to coat internal passages of turbine blades, for example to produce modified aluminide bond coats on single crystal nickel based superalloys. Originality/value: Chemical vapour deposition is an unique method which is a “pure method” and allows to coat hardly accessible locations/areas.