scholarly journals Degradation of Creep Resistant Ni - Alloy During Aging at Elevated Temperature Part II: Structure Investigations

2015 ◽  
Vol 15 (4) ◽  
pp. 45-50
Author(s):  
M. Kaczorowski ◽  
P. Skoczylas ◽  
A. Krzyńska
Keyword(s):  
Mechanical Properties ◽  
Cell Structure ◽  
High Stress ◽  
Dislocation Cell ◽  
Hydrogen Atmosphere ◽  
Structure Degradation ◽  
Transmission Electron ◽  
Δ Phase ◽  
Structure Investigations

Abstract The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K and 850K are presented. The structure investigation were carried out using conventional light-, scanning- (SEM) and transmission electron microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and growth of needle- and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γʺ phases. Moreover, it can’t be excluded that the least stable γʺ phase is replaced with more stable γʹ precipitates. TEM observations have disclosed differences in dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only, while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.

scholarly journals The Effect of Long-Term Impact of Elevated Temperature on Changes in Microstructure and Mechanical Properties of HR3C Steel

2016 ◽  
Vol 61 (2) ◽  
pp. 761-766 ◽  
Author(s):  
A. Zieliński ◽  
M. Sroka ◽  
A. Hernas ◽  
M. Kremzer
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Quantitative Identification ◽  
Working Parameters ◽  
Long Term Impact

Abstract The HR3C is a new steel for pressure components used in the construction of boilers with supercritical working parameters. In the HR3C steel, due to adding Nb and N, the compounds such as MX, CrNbN and M23C6 precipitate during service at elevated temperature, resulting in changes in mechanical properties. This paper presents the results of microstructure investigations after ageing at 650, 700 and 750 °C for 5,000 h. The microstructure investigations were carried out using scanning and transmission electron microscopy. The qualitative and quantitative identification of the existing precipitates was carried out using X-ray analysis of phase composition. The effect elevated temperature on microstructure and mechanical properties of the examined steel was described.

Effect of Annealing Temperature on the Microstructure of 2195 Al-Li Alloy Sheet

2021 ◽  
Vol 1026 ◽  
pp. 49-58
Author(s):  
Bo Feng ◽  
Bai Qing Xiong
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Annealing Temperature ◽  
Testing Machine ◽  
Annealing Treatment ◽  
Alloy Sheet ◽  
Transmission Electron ◽  
Δ Phase ◽  
Backscattered Electron ◽  
Alloy Increase

The annealing temperature is a key parameter for the mechanical properties and microstructure control of the 2195 Al-Li alloy sheet in the annealing process. In the present study, the effect of annealing temperature on the microstructure of 2195 Al-Li alloy sheet was investigated using a general mechanical testing machine, scanning electron microscope (SEM), transmission electron microscope (TEM), and backscattered electron microscope (EBSD). It was found that the optimized annealing temperature for 2195Al-Li alloy sheet of H112 state is 400°C, the alloy sheet shows the satisfactory mechanical properties. In addition, with the increase of annealing temperature, the δ' phase, the θ' phase and the T1 phase are formed in the alloy sheet, which leads to the strength of the alloy increase. Furthermore, the annealing temperature obviously affect the texture component and intensity during annealing treatment process.

scholarly journals Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 491 ◽  
Author(s):  
Volodymyr Hutsaylyuk ◽  
Pavlo Maruschak ◽  
Ihor Konovalenko ◽  
Sergey Panin ◽  
Roman Bishchak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Damage Accumulation ◽  
Classification Scheme ◽  
Steel Structure ◽  
Term Operation ◽  
Gas Main ◽  
Structure Degradation ◽  
Main Pipelines

Regularities of steel structure degradation of the “Novopskov-Aksay-Mozdok” gas main pipelines (Nevinnomysskaya CS) as well as the “Gorky-Center” pipelines (Gavrilovskaya CS) were studied. The revealed peculiarities of their degradation after long-term operation are suggested to be treated as a particular case of the damage accumulation classification (scheme) proposed by prof. H.M. Nykyforchyn. It is shown that the fracture surface consists of sections of ductile separation and localized zones of micro-spalling. The presence of the latter testifies to the hydrogen-induced embrittlement effect. However, the steels under investigation possess sufficiently high levels of the mechanical properties required for their further safe exploitation, both in terms of durability and cracking resistance.

Electronic Structure Investigations of γ-Tial.

1997 ◽  
Vol 3 (S2) ◽  
pp. 995-996
Author(s):  
K. Lie ◽  
R. Holmestad ◽  
K. Marthinsen ◽  
R. Høier
Keyword(s):  
Electronic Structure ◽  
High Stress ◽  
Mean Free Path ◽  
Edge Structure ◽  
Transmission Electron ◽  
Nominal Voltage ◽  
Lower Temperature ◽  
Convergent Beam ◽  
Structure Investigations ◽  
Inelastic Mean Free Path

The intermetallic compound TiAl is a promising material for applications at high stress and high temperature. It has good balance between lightness, strength and oxidation resistance, but suffers of an intrinsic brittleness at lower temperature. Small, ternary additions of V, Cr or Mn are known to increase the ductility of this material. In the present and a recent study we have used electron energy loss spectroscopy as a sensitive test to investigate the electronic structure in these materials. The near edge structure (NES) may give complementary information to e.g. convergent beam electron diffraction (CBED) about the bonding character in these materials.EELS spectra were collected using a Gatan 666 spectrometer with parallel recording fitted to a Philips CM 30 transmission electron microscope operating at a nominal voltage of 150 kV. The energy resolution (measured as full width at half maximum) was typically around 1 eV. Spectra from areas of similar thickness, as measured relative to the total inelastic mean free path of the 150-keV electrons were obtained.

scholarly journals The Influence of Cyclic Sintering on the Structure and Mechanical Properties of Tungsten Heavy Alloy

2016 ◽  
Vol 16 (4) ◽  
pp. 131-136 ◽  
Author(s):  
P. Skoczylas ◽  
M. Kaczorowski
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Main Part ◽  
Hydrogen Atmosphere ◽  
Liquid Phase Sintering ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Structure Investigations ◽  
Scanning Electron ◽  
Mechanical Studies

Abstract The results of structure and mechanical properties investigations of tungsten heavy alloy (THA) after cyclic sintering are presented. The material for study was prepared using liquid phase sintering of mixed and compacted powders in hydrogen atmosphere. The specimens in shape of rods were subjected to different number of sintering cycles according to the heating schemes given in the main part of the paper From the specimens the samples for mechanical testing and structure investigations were prepared. It follows from the results of the mechanical studies, that increasing of sintering cycles lead to decrease of tensile strength and elongation of THA with either small or no influence on yield strength. In opposite to that, the microstructure observations showed that the size of tungsten grain increases with number of sintering cycles. Moreover, scanning electron microscope (SEM) observations revealed distinctly more trans-granular cleavage mode of fracture in specimens subjected to large number of sintering cycles compared with that after one or two cycles only.

scholarly journals Changes In Properties and Microstructure of High-Chromium 9-12%Cr Steels Due to Long-Term Exposure at Elevated Temperature

2016 ◽  
Vol 61 (2) ◽  
pp. 957-964 ◽  
Author(s):  
A. Zieliński ◽  
J. Dobrzański ◽  
H. Purzyńska ◽  
G. Golański
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Phase Composition ◽  
High Chromium ◽  
X Ray ◽  
Supercritical Steam Parameters ◽  
Transmission Electron ◽  
Steam Parameters

AbstractThis paper presents the characteristics of the performance of P91 (X10CrMoVNb9-1), P92 (X10CrWMoVNb9-2) and VM12 (X12CrCoWVNb12-2-2) steels used for condition assessment of the pressure components of boilers with supercritical steam parameters. Studies on the mechanical properties, microstructure tests using scanning and transmission electron microscopy, and X-ray analysis of the phase composition of precipitates were performed for selected steels in the as-received condition and after long-term annealing. These steel characteristics are used for the evaluation of the microstructural changes and mechanical properties of the material of components after long-term service. The result of this study is the database of material characteristics representing the mechanical properties related to the microstructure analysis and it can be used for diagnosis of the components of pressure parts of power boilers.

scholarly journals Preliminary Study of the Rhenium Addition on the Structure and Mechanical Properties of Tungsten Heavy Alloy

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7365
Author(s):  
Paweł Skoczylas ◽  
Mieczysław Kaczorowski
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Hydrogen Atmosphere ◽  
Liquid Phase Sintering ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Preliminary Study ◽  
Rhenium Addition ◽  
Structure Investigations ◽  
Mechanical Studies

The results of structure and mechanical property investigations of tungsten heavy alloy (THA) with small additions of rhenium powder are presented. The material for the study was prepared using liquid phase sintering (LPS) of mixed and compacted powders in a hydrogen atmosphere. From the specimens, the samples for mechanical testing and structure investigations were prepared. It follows from the results of the microstructure observations and mechanical studies, that the addition of rhenium led to tungsten grain size decreasing and influencing the mechanical properties of W-Ni-Fe-Co base heavy alloy.

Microstructure and Mechanical Properties of G17CrMoV5 – 10 Cast Steel After Regenerative Heat Treatment

2009 ◽  
Author(s):  
Grzegorz Golan´ski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Regenerative Heat ◽  
Term Operation ◽  
Structure Degradation

The paper presents results of research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long term operation at the elevated temperature. The material under investigation was G17CrMoV5 – 10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250 000 hours. Performed research has proved that, through the structure degradation, long-term service contributes to an increase of brittleness and decrease of mechanical properties — higher in the case of yield strength than tensile strength. The heat treatment, however, contributes to an increase of impact energy, regardless of the applied parameters. Is has also been proved that the optimum combination of mechanical properties and impact energy is ensured by the structure of high tempered bainite. Low mechanical properties and impact energy, however, were obtained for the structure which was slowly cooled from the austenitizing temperature, i.e. the ferritic – bainitic – ferritic structure.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching

1995 ◽  
Vol 53 ◽  
pp. 538-539
Author(s):  
E Y. Wang ◽  
J. T. Cherian ◽  
A. Madsen ◽  
R. M. Fisher
Keyword(s):  
Steel Surface ◽  
Surface Preparation ◽  
Treatment Method ◽  
Chrome Plating ◽  
Transmission Electron ◽  
Alloy Steels ◽  
Pre Treatment ◽  
Hard Chrome ◽  
Electron Energy Loss

Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.

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