Rosenhain Centenary Conference - 2. Design implications for materials selection 2.4 High temperature mechanical properties as design parameters

The contribution of physical metallurgy to high temperature design is discussed under the headings of research, development, data collection, structural analysis, failure analysis, material selection, plant operation and failure investigation. Particular attention is drawn to the problems of transferring our available technology into our operating plant and it is suggested that further development of the status of the materials engineer is required. The paper highlights the significant contributions made by the metallurgist in microstructural studies, materials development, uniaxial data collection and failure investigations. For the future, it is suggested that much work remains to be done in the areas of crack growth, structural analysis and plant monitoring.

Author(s):  
Dr. Ramakotaiah Maddumala

A turbine blade is a machine component which makes up the turbine section of a gas turbine. These blades are responsible for extracting energy from the high temperature, high pressure gas produced by the combustor. The turbine blades are often the limiting component of the gas turbine. To survive in this difficult environment , turbine blades often use exotic materials like super alloys and many different methods of cooling , such as internal air channels and thermal barrier coatings. A common failure mode for turbine machine is high cycle of fatigue of compressor and turbine blades due to high dynamic stress caused by blade vibration and temperature has significant effect on gas turbine blades. The stresses with detrimental effect to the nozzle and blade were principally of thermal type, developed due to high temperature gradients across the air foil wall. These generate thermal fatigue mechanism and high steady state load leading to creep mechanism. In this project, a turbine blade is designed and modelled in NX Unigraphics software which is an advanced high-end CAD/CAE/CAM. The design is modified by changing the base of the blade to increase overall efficiency. Since the design of turbo machinery is complex and efficiency is directly related to material performance and material selection is of prime importance. In this project few materials are considered for turbine blade –titanium alloy and Nickel alloy. Optimisation will be done by varying the materials by performing structural analysis and thermal analysis on the turbine blades for both the designs


Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.


Author(s):  
W. M. Sherman ◽  
K. M. Vedula

The strength to weight ratio and oxidation resistance of NiAl make this ordered intermetallic, with some modifications, an attractive candidate to compete with many superalloys for high temperature applications. Recent studies have shown that the inherent brittleness of many polycrystalline intermetallics can be overcome by micro and macroalloying. It has also been found that the high temperature mechanical properties of NiAl can be enhanced through the addition of Nb by powder metallurgical techniques forming a dispersed second phase through interdiffusion in a polycrystalline matrix. A drop in the flow stress is observed however in a NiAl-2 at.% Nb alloy after 0.2 % strain during constant strain rate hot compression testing at 1025°C. The object of this investigation was to identify the second phase and to determine the cause of the flow stress drop.


Patan Pragya ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 19-32
Author(s):  
Chhabi Ram Baral

Urban poverty is one of multidimensional issue in Nepal. Increasing immigration from the outer parts of Kathmandu due to rural poverty, unemployment and weak security of the lives and the properties are core causes pushing people into urban areas. In this context how squatter urban area people sustain their livelihoods is major concern. The objectives of the study are to find out livelihood assets and capacities squatters coping with their livelihood vulnerability in adverse situation. Both qualitative and quantitative methods are applied for data collection. It is found that squatters social security is weak, victimized by severe health problems earning is not regular with lack of physical facilities and overall livelihood is critical. This study helps to understand what the changes that have occurred in livelihood patterns and how poor people survive in urban area.


2018 ◽  
Vol 55 (7) ◽  
pp. 424-446
Author(s):  
U. Jäntsch ◽  
M. Klimenkov ◽  
A. Möslang ◽  
F. Reinauer ◽  
J. Reiser ◽  
...  

Alloy Digest ◽  
1975 ◽  
Vol 24 (9) ◽  

Abstract BERYLCO NICKEL ALLOY 440 is an age-hardenable nickel-beryllium-titanium alloy that offers high strength, excellent spring properties outstanding formability, good high-temperature mechanical properties, and resistance to corrosion and fatigue. Complex shapes can be produced in the solution-treated (soft) condition and then aged to a minimum tensile strength of 215,500 psi. It is used for mechanical and electrical/electronic components in the temperature range -320 to 800 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-94. Producer or source: Kawecki Berylco Industries Inc.. Originally published September 1964, revised September 1975.


Alloy Digest ◽  
1973 ◽  
Vol 22 (1) ◽  

Abstract HASTELLOY alloy S is a nickel-base high-temperature alloy having excellent thermal stability, good high-temperature mechanical properties and excellent resistance to oxidation up to 2000 F. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-184. Producer or source: Stellite Division, Cabot Corporation.


2006 ◽  
Vol 23 (1) ◽  
pp. 29-37 ◽  
Author(s):  
G.D. Janaki Ram ◽  
A. Venugopal Reddy ◽  
K. Prasad Rao ◽  
G. Madhusudhan Reddy

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