scholarly journals Microstructure and Properties of TiAl-Based Alloys Melted in Graphite Crucible

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 669
Author(s):  
Wojciech Szkliniarz ◽  
Agnieszka Szkliniarz
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Graphite Crucible ◽  
Strength Properties ◽  
Operating Conditions ◽  
Vacuum Induction Furnace ◽  
Intermetallic Alloys ◽  
Plastic Properties ◽  
Similar Chemical ◽  
Crucible Furnace ◽  
Successive Generations

This paper presents the chemical and phase composition, microstructure, and selected properties both at room temperature and at the temperature corresponding to the expected operating conditions of three successive generations of TiAl-based alloys (Ti-47Al-2W-0.5Si, Ti-45Al-8Nb-0.5(B,C), and Ti-45Al-5Nb-2Cr-1Mo-0.5(B,C)-0.2Si) melted in a vacuum induction furnace with high-density isostatic pressed graphite crucibles. The obtained results of mechanical and physical properties of the produced alloys were compared to the properties of reference alloys with similar chemical composition and melted in a cold copper crucible furnace. The effect of increased carbon content in the produced alloys due to the degradation of the graphite crucible during melting is higher strength properties, lower plastic properties, higher coefficient of thermal expansion, and improved creep resistance. It was shown that the proposed technology could be successfully used in the production of different generation TiAl-based intermetallic alloys.

Influence of alloying systems on the properties of single crystal nickel-based superalloys

2021 ◽  
Vol 112 (10) ◽  
pp. 794-799
Author(s):  
Alexander Glotka ◽  
Vadim Ol’shanetskii
Keyword(s):  
Single Crystal ◽  
Regression Models ◽  
Strength Properties ◽  
Term Limits ◽  
Alloying Elements ◽  
Structure Stability ◽  
Plastic Properties ◽  
Crystal Lattices ◽  
Predictive Regression ◽  
First Time

Abstract The purpose of the investigation was to obtain the predictive regression models that help correct the calculation of the mechanical properties of single crystal nickel-based superalloys without conducting prior experiments. The paper considers the influence of alloying elements on their tendency to form phases in foundry nickel-based superalloys. Using the elements influence on the phase formation, the coefficient Kc’ of the ratio of alloying elements for this class of alloys was set for the first time. We have revealed the short correlation of the ratio Kc’ with the dimensional misfit of γ and γ’ crystal lattices. Also, a high probability to predict the misfit for multicomponent nickel systems is shown, which significantly affected the strength properties. The regression models of correlation dependencies on the dimensional γ/γ’- misfit were offered to predict the short-term and long-term limits of the strength of alloys. We determined the operating temperature at which the misfit value should decrease to zero. The structure stability should increase because of the structural stresses minimizing. This has a positive effect on strength and plastic properties.

scholarly journals THE ABILITY TO CLINCHING AS A FUNCTION OF MATERIAL HARDENING BEHAVIOR

2018 ◽  
Vol 24 (1) ◽  
pp. 58
Author(s):  
Tadeusz Balawender
Keyword(s):  
Strain Hardening ◽  
Strength Properties ◽  
Strain Hardening Exponent ◽  
Special Importance ◽  
Metallic Materials ◽  
Forming Process ◽  
Plastic Properties ◽  
Plastic Materials ◽  
Mechanical Clinching ◽  
Induced Defects

<p><span lang="EN-GB">Mechanical clinching can be used to joining different metallic materials. The only restriction are their plastic properties. However some plastic materials, with good ductility, do not conform strong clinch joint, e.g. materials, featured by high strain hardening phenomena are difficult to clinching and do not create durable clinch joint. In case of others materials with limited ductility clinch forming generates the process-induced defects such as cracks. So, there are material’s features which are very important for the clinch forming process and among them the strain hardening properties seem to be in special importance.</span></p><p><span lang="EN-GB"><span>                </span>The clinch joints of different materials with diversified plastic and strength properties<span>  </span>were tested. A single overlap clinch joints with one clinch bulge were realized in the tests. The joints were tested in the pull test. The obtained results showed the relation of the clinch joinability to the materials’ strain hardening exponent. The good quality and good strength joints, were obtained for materials with low value of strain hardening<span>  </span>exponent below n = 0,22.</span></p>

scholarly journals Study of the structure and characteristics of autoclaved aerated concrete

2020 ◽  
pp. 23-32
Author(s):  
Veronika Aleksandrovna Alipova
Keyword(s):  
Building Material ◽  
Coefficient Of Thermal Expansion ◽  
Weight Ratio ◽  
Strength Properties ◽  
Sound Insulation ◽  
Vapor Permeability ◽  
Conventional Concrete ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Manufacturing Technologies

The lightweight and porous building material has many advantages over conventional concrete, such as a higher strength-to-weight ratio, a lower coefficient of thermal expansion and good sound insulation. This article focuses on the historical periodization of the development of autoclaved aerated concrete and a literature review that focuses on the influence of porosity, vapor permeability and strength properties of a given building material. The subject of this research is the analysis of the key historical events and manufacturing technologies that influenced the creation and transformation of the structural components of autoclaved aerated concrete. In the course of research, the author revealed that although aerated concrete is a&nbsp;new material in construction, it appeared a long time ago. Initially, five thousand years ago,&nbsp;this composition of the material was used as a plaster and&nbsp;brickwork mortar; showing a positive effect in construction, the aerated concrete over the years took the form of a cellular block, and its characteristics continue to be discovered. The properties, composition and structure of autoclaved aerated concrete are being improved through its composition and geometry of the shape of block,&nbsp;which contributed&nbsp;to environmental friendliness of the new building material, its durability,&nbsp;and creation of&nbsp;comfortable living conditions for people.&nbsp;However,&nbsp;the material requires&nbsp;new rational manufacturing technologies are needed in order to improve&nbsp;its quality and characteristics.

scholarly journals EFFECTIVENESS EVALUATION OF STEEL STRENGTH IMPROVEMENT FOR PYRAMIDAL-PRISMATIC BUNKERS

2020 ◽  
Vol 2 ◽  
pp. 30-38
Author(s):  
Yukhym Hezentsvei ◽  
Dmytro Bannikov
Keyword(s):  
Low Temperatures ◽  
High Strength ◽  
Operating Conditions ◽  
Professional Literature ◽  
Plastic Properties ◽  
Repair Work ◽  
Practical Engineering ◽  
Cis Countries ◽  
The Right ◽  
The Cost

In accordance with the recommendations of specialized professional literature, steel pyramidal-prismatic bunkers are projected for a service life of 20 years. However, in practice this term is often twice, or even three times lower. This is especially true for complicated operating conditions, in particular the effect of increased loads and low temperatures. Existing design techniques for such structures, both in European practice and the design practice of Ukraine and other CIS countries do not pay attention to these aspects. Therefore, in the practice of operation, the increased accident rate of steel bunker capacities has already become virtually a common occurrence. One of the possible ways to solve this problem is presented, which consists of using instead of traditional steels of ordinary strength with high plastic properties, steels of increased or high strength with reduced plastic properties. At the same time, clear theoretical recommendations are provided for choosing the right steel depending on the operating conditions, primarily when exposed to increased loads. The recommendations are presented in a form convenient for practical engineering applications. The proposed approach allows to reduce the material consumption of structures of this type on average according to theoretical estimates by 25-30% without reducing their bearing capacity. Their durability is also further enhanced by improving performance at low temperatures. Thus, the applied aspect of such a solution to this above problem is the possibility of increasing the overall reliability of steel bunker capacities, as well as reducing the cost of their periodic maintenance and repair work. A practical illustration of the presented approach is also given on the example of the design of bunkers of a bypass track for supplying charge materials for blast furnaces of one of the metallurgical plants of the northern location. As a result, this created the preconditions for monetary savings of about 0.5 million UAH in prices 2019 (about 20,000 USD)

Obtaining of Ni Base Intermetallic Alloys by Solidification Control

2007 ◽  
Vol 23 ◽  
pp. 283-386
Author(s):  
Mariana Lucaci ◽  
Radu L. Orban ◽  
M. Lazarescu ◽  
Stefania Gavriliu ◽  
Magdalena Lungu ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Directional Solidification ◽  
Induction Furnace ◽  
Vacuum Induction Furnace ◽  
Surface Chemical ◽  
Intermetallic Alloys ◽  
Surface Chemical Composition ◽  
Master Alloys ◽  
Solidification Control ◽  
Cylindrical Samples

Directional solidification techniques have been applied to produce Ni based intermetallic alloys with preferentially oriented columnar crystals extended along the complete length and parallel to the solidification direction. Enhanced ductility is expected from such alloys. In this paper we present the research results concerning the application of this technique to some complex Ni3Al- Fe-B alloys obtained from compacted mixtures of elemental powders. The corresponding master alloys have been obtained in a vacuum induction furnace by the known Exo-Melt process [1]. The directional solidification of these alloys was subsequently performed on cylindrical samples, at two solidification rates, 30 and 15 mm/h. The influence of the rate and composition used on the dimensional variations, densities, microstructure, constituent phases and lattice parameters, as well as on the surface chemical composition have been documented and are presented in the paper.

Experience With Large Heavy-Duty Gas Turbine Rotors

1981 ◽  
Author(s):  
O. R. Schmoch ◽  
B. Deblon
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Strength Properties ◽  
Operating Conditions ◽  
Material Strength ◽  
Heavy Duty ◽  
Turbine Rotors ◽  
Heavy Duty Gas Turbine ◽  
Response To Temperature

The peripheral speeds of the rotors of large heavy-duty gas turbines have reached levels which place extremely high demands on material strength properties. The particular requirements of gas turbine rotors, as a result of the cycle, operating conditions and the ensuing overall concepts, have led different gas turbine manufacturers to produce special structural designs to resolve these problems. In this connection, a report is given here on a gas turbine rotor consisting of separate discs which are held together by a center bolt and mutually centered by radial serrations in a manner permitting expansion and contraction in response to temperature changges. In particular, the experience gained in the manufacture, operation and servicing are discussed.

scholarly journals Microstructure and mechanical properties of HR6W alloy dedicated for manufacturing of pressure elements in supercritical and ultrasupercritical power units

2019 ◽  
Vol 82 ◽  
pp. 01005 ◽  
Author(s):  
Grzegorz Golański ◽  
Agata Merda ◽  
Adam Zieliński ◽  
Paweł Urbańczyk ◽  
Jacek Słania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Yield Strength ◽  
Base Alloy ◽  
Strength Properties ◽  
Laves Phase ◽  
Plastic Properties ◽  
The Matrix ◽  
Isothermal Ageing ◽  
Nickel Base

The article presents the results of research on the microstructure and selected mechanical properties of HR6W nickel-base alloy. The test alloy was subjected to isothermal ageing at 700°C and for up to 10000h. The tests of the HR6W microstructure were performed using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The performed microstructural tests of the HR6W alloy showed that in the as-received condition it was characterised by the structure of nickel austenite with numerous primary precipitates of NbC and TiN. Ageing of the investigated alloy contributed to the precipitation of numerous particles of varying morphologies inside the grains and at the grain boundaries, as well as at the boundaries of twins - they were the secondary precipitates of M23C6 and Laves phase. The number of the particles precipitated at the boundaries was so large that they formed the so-called continuous grid of precipitates. Inside the grains, the presence of compound complexes of precipitates was observed. These complexes consisted of the TiN particles, as well as the M23C6 carbides and Laves phase nucleating on them. The tests of the mechanical properties of HR6W alloy showed that in the as-received condition the alloy showed high plastic properties, with relatively low strength properties - in particular, the yield strength. Ageing of the HR6W alloy, as a result of precipitation of numerous particles in the matrix, through the strengthening with the precipitation mechanism, resulted in a considerable growth of the strength properties - inter alia the yield strength by over 60%, with the reduction of the plastic properties - elongation decreased by around 40%. Similar growth in the test alloy was observed for hardness.

scholarly journals The tribological properties of Al-brasses in various environments

2017 ◽  
Vol 61 (3) ◽  
pp. 91-94
Author(s):  
M. Lovíšek ◽  
T. Liptáková ◽  
J. Bronček ◽  
S. Dundeková
Keyword(s):  
Tribological Properties ◽  
Room Temperature ◽  
Tribological Behavior ◽  
Cold Drawing ◽  
Operating Conditions ◽  
Air Cooling ◽  
Normal Loading ◽  
Dry Air ◽  
Similar Chemical ◽  
Made In

Abstract Tribological properties of Al-brass pipes of various producers were studied in different environments. The tested brasses have very similar chemical composition, but they differ in microstructure due to mainly by heat treatment after cold drawing. Microstructure as well as roughness of surface influence chemical and mechanical properties which are important in operating conditions. The experiments of tribological behavior were made in various environments, dry air, cooling treated water and 3.5 % solution of NaCl at room temperature 21 ± 2°C. The tribological tests were carried out on the Linear Tribometer at normal loading 5 N by the method ball on plate for the duration of 5500 s. The measured friction coefficients were evaluated by the program DIAdem and the diagrams were created from signal generated by software NSignal Express

Numerical Simulation of Forming Process for Cover with Stiffening Components Made of Grade 2 Titanium Sheet Metal

2016 ◽  
Vol 687 ◽  
pp. 206-211
Author(s):  
Wojciech Więckowski
Keyword(s):  
Numerical Simulation ◽  
Sheet Metal ◽  
Empirical Studies ◽  
Strength Properties ◽  
Forming Process ◽  
Titanium Sheet ◽  
Plastic Properties ◽  
Fem Method

This study presents the findings of numerical simulations of forming process for an inspection hole cover with stiffening ribs made of thin grade 2 titanium sheet metal. The numerical simulation was carried out using the FEM method with PAMStamp 2G software. Numerical calculations were performed with consideration for the phenomenon of material strain hardening and anisotropy of plastic properties of the sheet metal formed. Properties of the grade 2 titanium alloy analysed in the simulations were adopted based on the results of the empirical studies. Adequate parameters of the forming process were selected in order to eliminate unfavourable phenomena of losing of material coherence and sheet metal wrinkling. The effect of conditions of friction between the sheet metal and tool and pressure force of the blank holder on the forming process was investigated. The analysis of the distribution of plastic strain and reduction in wall thickness of the drawn parts can be used for determination of the effect of changes in selected parameters and orientation of the specimen on the process of drawn part forming. The quality of drawn parts was assessed based on the shape inaccuracy determined during simulation of forming. The inaccuracy depended on the conditions of the process and strength properties of the titanium sheet metal.

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