scholarly journals Micromechanics-Based Stress Rupture Life Prediction Of Polymer Composites

2005 ◽  
Vol 12 (1-2) ◽  
pp. 13-26
Author(s):  
T.J. Bandorawalla, ◽  
S.W. Case,
Keyword(s):  
Polymer Composites ◽  
Life Prediction ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

High Temperature Rupture Life of Nickel-Based Superalloy under Directional Solidification with High Temperature Gradient

2017 ◽  
Vol 898 ◽  
pp. 422-429 ◽  
Author(s):  
Wei Guo Zhang ◽  
Zhi Jie Liu ◽  
Song Ke Feng ◽  
Fu Zeng Yang ◽  
Lin Liu
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Temperature Stress ◽  
Solidification Rate ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Temperature Stress ◽  
Stress Rupture Life ◽  
Nickel Based Superalloy

The stress rupture life of DZ125 nickel-based superalloy that was prepared by directional solidification process under the temperature gradient of 500 K/cm has been studied at 900°C and 235MPa. The results showed that with the increase of directional solidification rate from 50 μm/s to 800 μm/s, the primary dendrite arm spacing reduced from 94 μm to 35.8 μm and γ' precipitates reduced and more uniformed in size. The high temperature stress rupture life of as-cast sample increased firstly and then decreased and reached its maximum at the solidification rate of 500 μm/s. The dislocation configuration of sample with refine dendritic structure after stress rupture was investigated and discovered that the dislocations in different parts of sample had different morphology and density, which indicated that the deformation of as-cast samples were uneven during high temperature stress rupture. A lot of dislocations intertwined around carbides and at the interface of γ/γ', and the dislocation networks were destroyed and the dislocations entered γ' precipitate by the way of cutting.

Mutation in TCP phases and superior stress rupture life led by W/Mo ratio in Ni-based single crystal superalloys

2022 ◽  
pp. 131656
Author(s):  
Jinbin Chen ◽  
Jingyang Chen ◽  
Qinjia Wang ◽  
Yidong Wu ◽  
Qing Li ◽  
...  
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Tcp Phases

Effect of Microcast-X Fine Grain Casting on the Microstructure and Mechanical Properties of K492M Alloy at 760°C

2016 ◽  
Vol 849 ◽  
pp. 549-556
Author(s):  
Pin Pin Hu ◽  
Qi Dong Gai ◽  
Qing Li ◽  
Xin Tang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Rupture Life ◽  
Stress Rupture ◽  
Casting Alloy ◽  
Stress Rupture Life ◽  
Casting Technique ◽  
Conventional Casting ◽  
Fine Grain

The effect of Microcast-X fine grain casting on the microstructure and mechnical property K492M alloy at 760°C of was investigated. The results indicated that Microcast-X fine grain casting decreased grain size and dendrite space of γ′ phase and γ/γ′ eutectic. In addition, the element segregation decreased significantly compared to conventional casting technique. Also, the size and distribution of MC carbide were improved. By Microcast-X fine grain casting, the tensile strength increased from 934MPa of conventional casting alloy to 1089MPa and the elongation increased from 1.9% to 5.7%. In addition, the stress-rupture life increased from 28.8h of conventional casting alloy to 72.5h. And the fracture mechanism for the alloys by Microcast-X fine grain casting is trans-granular fracture toughness.

Stress Rupture Behavior of Disk Superalloys Exposed to Low-Temperature Hot Corrosion Environment

2020 ◽  
Author(s):  
Dipankar Dua ◽  
Mohammad Khajavi ◽  
Gary White ◽  
Deepak Thirumurthy ◽  
Jaskirat Singh
Keyword(s):  
Low Temperature ◽  
Hot Corrosion ◽  
Inconel 718 ◽  
Gas Turbines ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Corrosive Environments ◽  
The Impact ◽  
Temperature Surface

Abstract Siemens Energy has a large fleet of aero-derivative gas turbines. The performance and durability of these power turbines largely depend on the capability of hot section components to resist high-temperature surface attacks and to maintain their mechanical properties. Hot corrosion attack occurs due to exposure of turbine components to sulfur-bearing fuels/air together with other corrosive compounds during turbine operation. This paper investigates the impact of low-temperature hot corrosion on the stress rupture of commonly used gas turbine disk alloys, including Inconel 718, Incoloy 901, and A-286. The results indicate that Inconel 718 and Incoloy 901 maintain their creep strength advantage over A-286 in a low-temperature hot corrosion inducing environment at 1100°F. All three materials exhibited an equivalent life reduction in the corrosive environments at 1100°F. Moreover, the results demonstrate that the stress-rupture life of materials in hot-corrosion environments depends on the combined and cumulative effects of corrosion-resistant and hardening elements.

scholarly journals Influence Mechanism of Silicon on Carbide Phase Precipitation of a Corrosion Resistance Nickel Based Superalloy

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 959 ◽  
Author(s):  
Tao Liu ◽  
Mei Yang ◽  
Fenfen Han ◽  
Jiasheng Dong
Keyword(s):  
Carbide Phase ◽  
Silicon Content ◽  
Rupture Life ◽  
Stress Rupture ◽  
Low Carbon ◽  
Stress Rupture Life ◽  
Corrosion Resistant ◽  
Stress Rupture Properties ◽  
Corrosion Resistant Alloy ◽  
Rupture Properties

The effect of silicon on diffusion behavior of the carbide forming elements in Ni-Mo-Cr-Fe based corrosion-resistant alloy is studied by diffusion couple experiment. One group of diffusion couples are made of the alloy with a different silicon content, another group of diffusion couples are made of pure nickel and the alloy with different silicon content (0Si, 2Si). Two groups of alloys with same silicon content and different carbon content are also prepared, the microstructure of solution and aging state of these two groups alloys are analyzed, and their stress rupture properties are tested. The effect of silicon on the diffusion of alloy elements and the interaction effect of carbon and silicon on the microstructure and stress rupture properties of the alloy are analyzed. The mechanism of Si on the precipitation behavior of carbide phase in Ni-Mo-Cr-Fe corrosion resistant alloy is discussed. The results show that silicon can promote the diffusion of carbide forming elements and the formation of carbide. The precipitation behavior of the secondary phase is the result of the interaction effect of silicon and carbon, and is related to the thermal history of the alloy. Combined with the characteristic of primary carbides, it is confirmed that the precipitation of M12C type secondary carbide is caused by the relative lack of carbon element and the relative enrichment of carbide forming elements such as molybdenum. The stress rupture properties of two silicon-containing alloys with different carbon contents in solution and aging state are tested. The stress rupture life of low carbon alloy is lower compared with high carbon alloy at solution state, but after aging treatment, the stress rupture life of low carbon alloy is significantly improved, and higher than that of high carbon alloy. The main aim of this research is to reveal the influence mechanism of silicon on carbide phase precipitation of a Ni-Mo-Cr-Fe based corrosion-resistant superalloy, which provides theoretical basis and reference for later alloy design and engineering application.

Influence of Heat Treatment on the Microstructures and Mechanical Properties of K465 Superalloy

2016 ◽  
Vol 849 ◽  
pp. 570-579
Author(s):  
Qiang Huang ◽  
Jin Xia Song ◽  
Qing Li ◽  
Wei Peng Ren ◽  
Xin Guang Guan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Room Temperature ◽  
Rupture Life ◽  
Tensile Elongation ◽  
Solution Treatment ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Microstructures And Mechanical Properties

The microstructures and mechanical properties of superalloy K465 under different heat treatment, including as as-cast, solution treatment and aging, were investigated. The results showed that γ' precipitates in as-cast condition exhibited two kinds of morphologies of fine regular cuboidal shape at dendritic arm and coarse irregular form in interdendritic region. MC carbides decomposed into M6C carbides partly after 1210°C/4h solution treatment. The high temperature stress-rupture life can be improved obviously with the increasing cooling rate. When cooling rate was lower than 70°C/min, the room temperature tensile elongation increased with cooling rate increasing. When cooling rate was higher than 90°C/min the room temperature tensile elongation decreased with cooling rate increasing. The proper cooling rate of 70oC/min~90oC/min is advantageous for the achievement of excellent comprehensive properties. When aging treatments continued the regularization of γ' resulted in the improvement of stress-rupture life and the reduction of tensile elongation. The mechanical property gap between the solution treatment and aging can be decreased with increasing cooling rate.

Improvement of Stress-rupture Life for Modified-HR6W Austenitic Stainless Steel

2011 ◽  
Vol 27 (11) ◽  
pp. 1059-1064 ◽  
Author(s):  
Shiyun Cui ◽  
Zixing Zhang ◽  
Yulai Xu ◽  
Jun Li ◽  
Xueshan Xiao ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life

scholarly journals The Feasibility of Water Injection Into the Turbine Coolant to Permit Gas Turbine Contingency Power for Helicopter Application

1983 ◽  
Vol 105 (3) ◽  
pp. 635-642 ◽  
Author(s):  
G. J. Van Fossen
Keyword(s):  
Temperature Rise ◽  
Rupture Life ◽  
Stress Rupture ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Stress Rupture Life ◽  
Barrier Coating ◽  
Power Turbine ◽  
Turboshaft Engine

A system which would allow a substantially increased output from a turboshaft engine for brief periods in emergency situations with little or no loss of turbine stress rupture life is proposed and studied analytically. The increased engine output is obtained by turbine overtemperature; however, the temperature of the compressor bleed air used for hot section cooling is lowered by injecting and evaporating water. This decrease in cooling air temperature can offset the effect of increased gas temperature and increased shaft speed and thus keep turbine blade stress rupture life constant. The analysis utilized the Navy NASA Engine Program or NNEP computer code to model the turboshaft engine in both design and off-design modes. This report is concerned with the effect of the proposed method of power augmentation on the engine cycle and turbine components. A simple cycle turboshaft engine with a 16:1 pressure ratio and a 1533 K (2760° R) turbine inlet temperature operating at sea level static conditions was studied to determine the possible power increase and the effect on turbine stress rupture life that could be expected using the proposed emergency cooling scheme. The analysis showed a 54 percent increase in output power can be achieved with no loss in gas generator turbine stress rupture life. A 231 K (415° F) rise in turbine inlet temperature is required for this level of augmentation. The required water flow rate was found to be 0.0109 kg water per kg of engine air flow. For a 4.474 MW (6000 shp) engine this would require 32.26 kg (71.13 lbm) of water for a 2.5 min transient. At this power level, approximately 25 percent of the uncooled power turbine life is used up in a 2 1/2-min transient. If the power turbine were cooled, this loss of stress-rupture life could be reduced to zero. Also presented in this report are the results of an analysis used to determine the length of time a ceramic thermal barrier coating would delay the temperature rise in hot parts during operation at elevated temperatures. It was hoped that the thermal barrier could be used as a scheme to allow increased engine output while maintaining the life of hot section parts during short overtemperature transients. The thermal barrier coating was shown to be ineffective in reducing blade metal temperature rise during a 2.5-min overtemperature.

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