scholarly journals Evaluation of the residual life and mechanical properties of steels with a heterophase structure

2019 ◽  
Author(s):  
V. P. Shveikin
Keyword(s):  
Mechanical Properties ◽  
Residual Life ◽  
Heterophase Structure

scholarly journals Assessment of Service Life of HCM12 Steel After 100 000 Hrs of Service

2016 ◽  
Vol 61 (2) ◽  
pp. 1021-1029 ◽  
Author(s):  
A. Zieliński ◽  
H. Paszkowska ◽  
P. Skupień ◽  
G. Golański
Keyword(s):  
Mechanical Properties ◽  
Creep Resistance ◽  
Residual Life ◽  
Strength Properties ◽  
Steam Superheater ◽  
Significant Loss ◽  
Creep Tests ◽  
Supercritical Steam Parameters ◽  
Steam Parameters ◽  
The Impact

AbstractThe subject of the research was a material in the form of a ϕ38×4 pipe from HCM12 steel used for steam superheater coils in power boilers with supercritical and ultra-supercritical steam parameters. This article presents results of investigations of mechanical properties and microstructure of material of the examined tube in the as-received condition and after 100,000 h service at 585°C under creep conditions. Creep tests were carried out for the material after 100,000 h service to determine the disposable residual life. The impact of changes in mechanical properties and degradation of the microstructure on the loss of creep resistance compared to the as-received condition was assessed. The investigations have revealed that the examined steel after 100,000 h service meets the requirements for this steel in the as-received condition with regard to strength properties at room and elevated temperature. The creep tests have revealed a significant loss of creep resistance, which was estimated at around 60-70% compared to the as-received condition.

Evolution of Thermal Barrier Coating Strain Tolerance During Engine Operation and its Application to Lifing Models

2012 ◽  
Author(s):  
Markus Schaudinn ◽  
Grégoire Witz ◽  
Hans-Peter Bossmann
Keyword(s):  
Mechanical Properties ◽  
Thermal Barrier Coating ◽  
Residual Life ◽  
Propagation Model ◽  
Ceramic Layer ◽  
Limiting Factor ◽  
Thermal Barrier ◽  
Engine Operation ◽  
Strain Tolerance ◽  
Barrier Coating

Models for thermal barrier coating lifetime prediction are often based on bondcoat oxidation models leading to an end of life criterion either based on bondcoat full consumption or a critical thermally grown oxide thickness. Such models can be satisfactory on turbine parts where the most common coating delamination modes are black or grey failure which are linked to the bondcoat behaviour. Such models are not reliable for combustor parts with thick thermal barrier coating systems where the most common life limiting factor is the formation of cracks appearing in the ceramic layer few tens of microns above the bondcoat interface. This behaviour is linked to the TBC layer mechanical properties and should be described by a model taking into account the evolution of the TBC mechanical properties during engine operation, the mechanical loads in the ceramic layer and a crack propagation model in the TBC. A study of the strain tolerance of TBC from combustor parts after engine operation was performed by taking samples from combustor liners at various locations having different TBC surface temperature. The strain tolerance of TBC samples was measured by four-point bending and correlated with the TBC microstructure and various engine operation parameters. It was shown that the TBC microstructure has an influence on TBC strain tolerance, and that the evolution of the TBC strain tolerance during engine operation is linked to the TBC temperature as well as the operating hours. The data have been used to develop a predictive model of the evolution of the TBC strain tolerance during engine operation. This model allows optimization of parts reconditioning interval, and provides tools for determining the residual life of coated components.

Fatigue Response of Hybrid Ti/APC-2 Nanocomposite Laminates with Single-Edged Cracks

2013 ◽  
Vol 592-593 ◽  
pp. 425-428
Author(s):  
Ming Hwa R. Jen ◽  
Che Kai Chang ◽  
Bo Cyuan Lin
Keyword(s):  
Mechanical Properties ◽  
Crack Length ◽  
Composite Laminates ◽  
Residual Life ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Paris Law ◽  
Modified Method ◽  
Longitudinal Stiffness ◽  
Static Tensile

The aims of this study are to fabricate Ti/APC-2 hybrid composite laminates with and without (W/WO) nanoparticles and investigate the mechanical properties of laminates with single-edged cracks due to both tensile and cyclic tests. The mechanical properties such as ultimate tensile strength and longitudinal stiffness of original composite laminates W/WO nanoparticles were first obtained from the static tensile tests. However, the load-displacement diagrams were plotted for the crack laminates. The constant stress amplitude tension-tension cyclic tests were conducted to receive the S-N curves and fatigue data. The ultimate strengths for both Ti/APC-2 composite laminates W/WO nanoparticles were very close at varied crack length. Ti/APC-2 cross-ply nanocomposite laminates had better fatigue resistance than that of laminates without nanoparticles. The longer the crack length is, the more their properties are reduced. Also, the values of fracture toughness of both hybrid cracked laminates W/WO nanoparticles were obtained by rule of mixtures and found acceptable. Finally, in predicting crack growth rate and residual life, instead of commonly used Paris Law for metals, the modified method was adopted for hybrid cracked laminates. The prediction is not satisfactorily acceptable, even if most results are in good agreement with empirical data.

scholarly journals The mechanical properties and fatigue responses of fiber metal nanocomposite laminates with double-edged cracks

2021 ◽  
Vol 37 ◽  
pp. 704-715
Author(s):  
Ming-Hwa R Jen ◽  
Li-Jen Hsu ◽  
Yu-Cheng Liang ◽  
Ying-Hui Wu
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Residual Life ◽  
Local Stress ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Crack Tips ◽  
Fiber Metal ◽  
Cracked Specimens

ABSTRACT The fiber metal laminates (FMLs) of hybrid Ti/APC-2 neat and nanocomposite laminates were fabricated. Geometrically symmetric and anti-symmetric double-edged cracks were cut in FMLs. From tensile tests, we received the load vs. displacement curves, stress intensity factors of mixed mode and mechanical properties. From cyclic tests, the load vs. cycles (P–N) curves, residual life and failure mechanisms were obtained. The mechanical properties of symmetrically cracked specimens were slightly lower than those of anti-symmetrically cracked counterparts. As the crack length increases and inclination angle decreases, the fatigue life decreases. The enhancement of nanopowder improved the ultimate load and fatigue life. The local stress intensity at the crack tip dominates the fatigue responses. The piece of elliptical part was observed from cyclic tests at failure. Although the attraction of two crack tips accelerated the crack growth towards each other, the delay to failure was caused by two crack tips circling around and forming a small piece of ellipse centrally.

Condition Monitoring of High Temperature Components With Sub-Sized Samples

2008 ◽  
Author(s):  
Wolfgang Hoffelner ◽  
Manuel Pouchon ◽  
Maria Samaras ◽  
Annick Froideval ◽  
Jiachao Chen
Keyword(s):  
Mechanical Properties ◽  
Condition Monitoring ◽  
Focused Ion Beam ◽  
Residual Life ◽  
Ion Beam ◽  
Oxide Dispersion Strengthened ◽  
Dislocation Dynamics ◽  
Thin Strip ◽  
Small Samples ◽  
Term Operation

Advanced nuclear plants are designed for long-term operation in quite demanding environments. Limited operation experience with the materials used in such plants necessitate a reliable assessment of damage and residual life of components. Non-destructive condition monitoring of damage is difficult, if not impossible for many materials. Periodic investigation of small samples taken from well defined locations in the plant could provide an attractive tool for damage assessments. This paper will discuss possibilities of using very small samples taken from plant locations for complementary condition monitoring. Techniques such as micro/nano-indentation, micropillar compression, micro bending, small punch and thin strip testing can be used for the determination of local mechanical properties. Advanced preparation techniques such as focused ion beam (FIB) allow the preparation of samples from these small volumes for micro-structural analyses with transmission electron microscope (TEM) and advanced X-ray synchrotron techniques. Modeling techniques (e.g. dislocation dynamics DD) can provide a quantitative link between microstructure and mechanical properties. Using examples from ferritic oxide dispersion strengthened materials the DD approach is highlighted to understand component life assessments.

scholarly journals Mechanical Properties and Fatigue Responses of Fiber Metal Nanocomposite Laminates with Double-Edged Cracks

2021 ◽  
Author(s):  
Ming-Hwa Jen ◽  
Li-Jen Hsu ◽  
Yu-Cheng Liang ◽  
Ying-Hui Wu
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Residual Life ◽  
Local Stress ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Nano Powder ◽  
Crack Tips ◽  
Fiber Metal ◽  
Inclined Angle

The fiber metal laminates (FMLs) of both Ti/APC-2 neat and nanocomposite laminates were fabricated. The double-edged cracks of both symmetry and anti-symmetry were cut in FMLs. From tensile tests we received the load vs. displacement curves and mechanical properties. From cyclic tests the load vs. cycles (P-N) curves, residual life, and failure mechanisms were obtained. The mechanical properties of symmetrically cracked specimens were slightly lower than those of anti-symmetrically cracked counterparts. As the crack length increasing and inclined angle decreasing, the fatigue life decreased. The enhancement of nano-powder improved the ultimate load and fatigue life. The local stress intensity at the crack tip dominates the fatigue responses. The piece of elliptical part was observed from cyclic tests at failure. Although the attraction of two crack tips accelerated the crack growth rate, however, the delay to failure was caused by forming a small piece of ellipse centrally.

Degradation of fuel rods materials based on zirconium after operation in WWER-type reactors

2019 ◽  
pp. 191-205 ◽  
Author(s):  
B. A. Gurovich ◽  
A. S. Frolov ◽  
E. A. Kuleshova ◽  
D. A. Maltsev ◽  
D. V. Safonov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Residual Life ◽  
Structural Elements ◽  
Dislocation Loops ◽  
Fuel Rods ◽  
E110 Alloy ◽  
Fuel Assemblies ◽  
Fuel Elements ◽  
Microstructural Studies

The paper presents microstructural studies of specimens cut from fuel elements made of E110 spongy zirconium-based alloy after operation in WWER-1000 before reaching the burnout of ~35 MW per day/kg U. As a result of exposure to high temperatures and neutron irradiation significant changes in the phase composition of the material of fuel rods claddings appear in particles β-Nb’ size, density, and composition; composition of the Laves phase, formation of dislocation loops of α-type, as well as δ and γ hydrides. The main structural elements determining the degradation of the mechanical properties of the E110 alloy under irradiation are dislocation loops and fine-phase precipitates due to their relatively large density. The data obtained can be used to construct dose dependences of microstructural changes with the aim of predicting the residual life of claddings and fuel assemblies as a whole.

Residual Life-Time Evaluation Method Using Instrumented Indentation Test

2019 ◽  
Vol 810 ◽  
pp. 89-94 ◽  
Author(s):  
Woo Joo Kim ◽  
Jung Jun Lee ◽  
Jong Ho Won ◽  
Dong Il Kwon
Keyword(s):  
Mechanical Properties ◽  
Evaluation Method ◽  
Residual Life ◽  
Thermal Power ◽  
Indentation Test ◽  
Life Time ◽  
Instrumented Indentation ◽  
Time Data ◽  
Actual Structure ◽  
Instrumented Indentation Test

Predicting the residual life of a structure is an essential issue in structure management. Many researchers have used different methods to predict structure lifetimes, such as the creep rupture test. However, this test is costly and time-consuming, and since it is also destructive, an unused specimen must be tested rather than an actual specimen in use. The instrumented indentation test (IIT), on the other hand, is easier and faster than conventional test methods, most important of all, it is a non-destructive method to obtain mechanical properties that can be performed on the actual structure in use. In this study, we obtained mechanical properties of a SA213-T23 tube material for a thermal power plant degraded for 1~2,000 hours at high temperature. and observed the degradation by analyzing the microstructure. We found a relation between the Larson-Miller Parameter (LMP) and degradation tensile properties considering the temperature and degradation time and suggested a method to predict the residual life by applying a failure criterion. Also, we confirmed that our interaction formula and the residual life are reasonable by comparison with statistical rupture time data from materials that have in fact degraded.

scholarly journals The Influence Of Repair Welded Joint On The Life Of Steam Pipeline Made Of Cr-Mo Steel Serviced Beyond The Calculated Working Time

2015 ◽  
Vol 60 (2) ◽  
pp. 1045-1049 ◽  
Author(s):  
A. Zieliński ◽  
G. Golański
Keyword(s):  
Mechanical Properties ◽  
Transition Temperature ◽  
Welded Joint ◽  
Residual Life ◽  
Base Material ◽  
Working Time ◽  
Safe Operation ◽  
Creep Tests ◽  
Steam Pipeline ◽  
Short Time

Abstract The aim of the paper was to examine the influence of repair welded joints on the service life of steam pipelines for over 220 000 hours of service in creep conditions. The research included the study of the microstructure using scanning microscopy, the tests on mechanical properties at room and elevated temperature, determining the nil ductility transition temperature, and short-time creep tests to determine the residual life of the material. The tests allowed determining the time of further safe operation of elements of the steam pipeline with a repair welded joint, with reference to the base material, and the welded joint after service. The assessment of residual life and disposable residual life, and at the same time determining the possible time of further safe operation, has an essential meaning in the case of elements serviced considerably beyond the calculated working time.

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