Case study: Failure Analysis of LPTR blade
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The document summarizes a case study of the failure of a low-pressure turbine rotor (LPTR) blade in a jet engine. Visual examination found a fatigue crack had initiated at the leading edge of the blade and propagated about 1 mm intergranularly and then about 11 mm transgranularly. Testing showed the microstructure at the leading edge had experienced dissolution of gamma prime precipitates, reducing the hardness and creep resistance. The failure mechanism involved initial stress rupture cracking at the leading edge followed by fatigue crack propagation. High operating temperatures caused the failure by dissolving precipitates and degrading the blade's strength properties.
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Advances in Special Steel: Maraging steel updated 2016
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- Hardening greatly increases strength by heating steel to the austenitizing temperature then quenching in water or oil to form martensite.
- Tempering is then used to reduce brittleness by reheating hardened steel to lower temperatures.
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This presentation provides an overview of friction welding. It discusses that friction welding is a solid state welding process where one part is rotated at high speeds up to 3000 rpm while being pressed against another part, generating heat through friction. This heat causes the parts to join without melting. Applications include automotive, agricultural, aerospace, and industrial parts. Advantages are that no filler material is needed, it is environmentally friendly with no fumes, and results in a narrow heat affected zone. Limitations are that it is only for joining round or rotatable parts of the same diameter.
7th Sem_Group 5.pptx
Friction welding is a solid-state welding process that joins two workpieces without melting them. It generates heat through mechanical friction caused by relative motion between the faying surfaces. This heat softens the surfaces, and an axial pressure is applied to merge the softened surfaces together. Friction welding produces high quality welds without using filler material. It is used in industries such as aerospace, automotive, and marine for components like tubes, shafts, gears, and valves. Benefits include joining dissimilar metals and producing welds with minimal waste.
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An optimal design approach for adamite hot rolling mill roll
In this paper, micro-structural, mechanical and tribological behaviors of roll materials i.e. high speed steel
(HSS), high chromium iron (HiCr), indefinite chill irons (IC) and other have been reviewed. The technological process of
the rolling consists of many factors that influencing the fatigue life of rolls like rolling temperature, roll groove design,
rolling speed and turning due to wearing. These parameters are analyzed to advance maximum fatigue life of the rolls as
well as to shrink overall energy consumption, increase production and decrease overall costs. Finite element analysis of
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roll wear. According to appropriate chemical properties, microstructure and mechanical property some new wearresistant roll grades for conventional hot rolling process is suggested.
Fatigue and creep
Fatigue and creep are fundamental mechanical properties of materials. Fatigue is the failure of a material caused by repeated application of cyclic stresses, even if the stresses are below the yield strength of the material. It can lead to loss of strength, ductility, and uncertainty in service life. Creep is the slow deformation of materials under a constant load at high temperatures. Creep deformation occurs in three stages - primary, secondary, and tertiary. Factors like temperature, grain size, heat treatment, and alloying elements affect the fatigue and creep properties of materials. Mechanisms like dislocation climb, vacancy diffusion, and grain boundary sliding contribute to creep deformation at high temperatures.
ACE305: Aircraft Components Design and Manufacture
Solid-state welding processes join materials without melting them and include friction welding, ultrasonic welding, roll bonding, and cold welding. Friction welding generates heat through friction between rotating and stationary parts in contact under pressure. Ultrasonic welding uses oscillating shear stresses to break up oxides and contaminants at the interface. Roll bonding applies pressure through rolls to join sheets. Resistance welding generates heat through electrical resistance and is used for spot welding sheets in automotive and other fabrication.
Mechanism of Fracture in Friction Stir Processed Aluminium Alloy
Aluminium alloys are used for important
applications in reducing the weight of the component and
structure particularly associated with transport, marine,
and aerospace fields. Grain refinement by scandium (Sc)
addition can eliminate the casting defects and increase the
resistance to hot tearing for high strength aluminium alloys.
FSP for cast aluminium alloys have been focused and it has
great advantages including solid state microstructural
evolution, altering mechanical properties by optimizing
process parameters. These parameters are tool rotational
speeds (720, and 1000 rpm), traverse speeds (80, and 70
mm/min), and axial compressive force at 15 kN, etc. The
mechanical properties had been evaluated on FSPed
aluminium alloy with different microstructural conditions.
Fracture properties of aluminium alloys are very important
for industrial applications. Tensile and fracture toughness
properties were correlated to microstructural and
fractographic features of the aluminium alloys need to
explore their essential failure mechanisms.
Various Techniques for Condition Monitoring of Three Phase Induction Motor- ...
Various Techniques for Condition Monitoring of Three Phase Induction Motor- ...International Journal of Engineering Inventions www.ijeijournal.com
Computer Science
Active and Programmable Networks
Active safety systems
Ad Hoc & Sensor Network
Ad hoc networks for pervasive communications
Adaptive, autonomic and context-aware computing
Advance Computing technology and their application
Advanced Computing Architectures and New Programming Models
Advanced control and measurement
Aeronautical Engineering,
Agent-based middleware
Alert applications
Automotive, marine and aero-space control and all other control applications
Autonomic and self-managing middleware
Autonomous vehicle
Biochemistry
Bioinformatics
BioTechnology(Chemistry, Mathematics, Statistics, Geology)
Broadband and intelligent networks
Broadband wireless technologies
CAD/CAM/CAT/CIM
Call admission and flow/congestion control
Capacity planning and dimensioning
Changing Access to Patient Information
Channel capacity modelling and analysis
Civil Engineering,
Cloud Computing and Applications
Collaborative applications
Communication application
Communication architectures for pervasive computing
Communication systems
Computational intelligence
Computer and microprocessor-based control
Computer Architecture and Embedded Systems
Computer Business
Computer Sciences and Applications
Computer Vision
Computer-based information systems in health care
Computing Ethics
Computing Practices & Applications
Congestion and/or Flow Control
Content Distribution
Context-awareness and middleware
Creativity in Internet management and retailing
Cross-layer design and Physical layer based issue
Cryptography
Data Base Management
Data fusion
Data Mining
Data retrieval
Data Storage Management
Decision analysis methods
Decision making
Digital Economy and Digital Divide
Digital signal processing theory
Distributed Sensor Networks
Drives automation
Drug Design,
Drug Development
DSP implementation
E-Business
E-Commerce
E-Government
Electronic transceiver device for Retail Marketing Industries
Electronics Engineering,
Embeded Computer System
Emerging advances in business and its applications
Emerging signal processing areas
Enabling technologies for pervasive systems
Energy-efficient and green pervasive computing
Environmental Engineering,
Estimation and identification techniques
Evaluation techniques for middleware solutions
Event-based, publish/subscribe, and message-oriented middleware
Evolutionary computing and intelligent systems
Expert approaches
Facilities planning and management
Flexible manufacturing systems
Formal methods and tools for designing
Fuzzy algorithms
Fuzzy logics
GPS and location-based appSimilar to Case study: Failure Analysis of LPTR blade (20)
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Advanced welding processes by Hamid Taghipour Armaki
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An optimal design approach for adamite hot rolling mill roll
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Mechanism of Fracture in Friction Stir Processed Aluminium Alloy
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Various Techniques for Condition Monitoring of Three Phase Induction Motor- ...
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Phase Transformation in Steel-Lecture Series- D (Displacive Transformation, M...
Phase Transformation in Steel-Lecture Series- D (Displacive Transformation, M...NED University of Engineering and Technology
1. Martensite forms via a diffusionless, displacive transformation in which the crystal structure changes rapidly without atomic diffusion.
2. The interface between austenite and martensite, called the habit plane, must be semi-coherent to allow rapid transformation. It consists of a set of dislocations that provide continuity between the crystals.
3. Martensitic transformation results in both a crystal structure change and a shape deformation of the material, as observed using interference microscopy techniques. The shape change is caused by a combination of volume expansion during the structure change coupled with simple shear deformation.Phase Transformation in Steel-Lecture Series- B (Displacive Transformation, B...
Phase Transformation in Steel-Lecture Series- B (Displacive Transformation, B...NED University of Engineering and Technology
1) Phase transformations in solid metals include the decomposition of austenite into other phases such as bainite, Widmanstätten ferrite, and acicular ferrite.
2) Bainite forms by the decomposition of austenite at a temperature above the martensite start temperature but below the temperature at which fine pearlite forms.
3) Widmanstätten ferrite nucleates from austenite grain boundaries and grows in a displacive mechanism, maintaining an atomic correspondence between the parent and product phases resulting in a triangular shape.
4) Acicular ferrite forms as thin plates within prior austenite grains or as sideplates from grain boundariesPhase Transformation in Steel- Lecture A 2023.pdf
The document discusses phase transformations in solid metals and alloys. It provides contact information for Dr. Muhammad Ali Siddiqui of NED University of Pakistan who teaches a course on this topic. It then lists several recommended textbooks on phase transformations and diagrams before outlining the topics that will be covered in the lecture series, including diffusion mechanisms, phase diagrams, and the classification of phase transformations.
Corrosion Testing's: OCP, LPR, and PD
The document discusses various corrosion testing techniques presented by Dr. Muhammad Ali Siddiqui of NED University of Engineering and Technology in Karachi, Pakistan. It describes open circuit potential (OCP) measurements, linear polarization resistance (LPR) testing, and potentiodynamic polarization measurements (PDMs). LPR uses the slope of the potential-current plot near corrosion potential to determine polarization resistance and corrosion rate. PDMs involve sweeping the potential from active to passive regions to obtain corrosion current, potentials, and characteristics of passive films. The document provides experimental procedures, examples, and data analysis for these electrochemical corrosion testing methods.
Lecture 2022-10-28.pdf
This document discusses corrosion engineering and corrosion testing. It begins with introductions to corrosion science and corrosion engineering. It then discusses the responsibilities of corrosion engineers, including ensuring safety and minimizing economic losses from corrosion. Direct economic losses include replacing corroded structures, while indirect losses include shutdowns and loss of efficiency. The document also summarizes various examples of corrosion, classifies corrosion into wet and dry types, and explains corrosion as an electrochemical reaction. It describes equipment used for corrosion testing like electrochemical workstations and defines key terms like potential and current. Finally, it discusses open circuit potential graphs used in corrosion testing.
Refining Slags.pptx
1. Slag is a molten oxide byproduct formed during smelting and refining of metals like steel. It contains both acidic oxides like SiO2 and basic oxides like CaO that neutralize each other.
2. An ideal slag for steelmaking has a basicity between 1.2-2.5, is sufficiently fluid, and can act as a thermal barrier while controlling the oxidation state of the steel through its FeO content.
3. The basicity, viscosity, oxidation potential, and ability to hold inclusions determine a slag's efficiency in refining steel of non-metallic impurities like phosphorus and sulfur.
Chinese traditional clothing
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Failure Analysis : Laboratory studies
Content :
Cleaning Techniques,
macrofractrography,
microfractrography,
metallography,
mechanical testing and
chemical analysis.
Failure Analysis Methodology
This document provides an overview of the methodology for conducting failure analysis of materials and components. It discusses collecting background information on the failed component and failure details. Key steps in the process include examining the failure site, documenting locations, collecting specimen samples, performing laboratory tests, analyzing test data, and preparing a report detailing the root cause failure mechanism. The methodology is a multidisciplinary approach requiring expertise across various engineering domains to properly analyze failures and prevent future occurrences.
Failure Analysis Methodology
The document outlines the methodology for conducting a failure analysis, including collecting background information on the failed component, examining the failure site, taking specimens for laboratory testing, analyzing test data, and preparing a report documenting the sequence of events leading to failure and providing recommendations. The process is multidisciplinary and aims to determine the root cause of failure through a systematic approach involving visual inspection, metallurgical examination, and mechanical testing of specimens from the failed component.
Lecture bainite, bainitic alloys and bulk nanocrystalline steel
Lecture bainite, bainitic alloys and bulk nanocrystalline steelNED University of Engineering and Technology
This document discusses the development of bulk nanocrystalline steel with exceptionally high strength. It describes how bainite formation through isothermal or continuous cooling transformation can produce a nanocrystalline microstructure in steel. A specific alloy composition is presented that achieves a nanocrystalline microstructure with 20-40nm thick ferrite plates after transforming at 200C for 10 days. This results in an ultrahigh strength of 2.5GPa but maintains good ductility. The technique allows large component manufacturing and is cost effective.Heat Treatment: Lecture Q&P, M3 concept
1. The document discusses the Schaeffler diagram, which is used to predict the microstructure of stainless steel welds based on their composition. It also discusses modifications to the diagram by Delong.
2. The M3 concept for developing third generation advanced high strength steels is described, which aims to achieve ultrahigh strength and ductility through a multi-phase, meta-stable, multi-scale microstructure.
3. Quenching and partitioning heat treatments are summarized as a novel method to produce multi-phase steels with significant retained austenite through quenching to form martensite and austenite, followed by an isothermal treatment to partition carbon into the a
Phase Transformation Lecture 3
1. Diffusion is the transport of atoms or molecules in solids, liquids, or gases due to a gradient in concentration or pressure. In solids, atoms constantly vibrate but bonds prevent long-range motion except through defects like vacancies.
2. There are two main diffusion mechanisms in solids - vacancy diffusion, where an atom hops into an adjacent vacant lattice site, and interstitial diffusion, where a small atom squeezes through spaces in the host lattice. Diffusion requires thermal energy to break bonds and depends strongly on temperature.
3. Fick's laws describe diffusion - the flux is proportional to the concentration gradient according to Fick's first law, and the rate of change of concentration
Phase Transformation Lecture equilibrium, Phase Diagram
Phase Transformation Lecture equilibrium, Phase Diagram NED University of Engineering and Technology
The document discusses phase transformations in solids. It defines phases as homogeneous regions of a material that are physically distinct. Phase transformations occur when an initial state becomes unstable relative to a final state. The stability of a system is determined by its Gibbs free energy (G), which depends on enthalpy (H), entropy (S), temperature (T), and pressure (P). Binary phase diagrams illustrate the phases present at various compositions and temperatures. Common diagram types include eutectic systems where components are soluble in liquid but not solid, and partially soluble solid systems. Determining phase amounts uses the lever rule based on composition and phase boundaries.Phase Transformation: Lecture Review of Phase Diagrams
Austenitic iron is non-magnetic, while ferritic iron is magnetic, due to their different temperatures rather than phases. Magnetism in iron arises from electron spin alignment within atomic zones. Above the Curie temperature, thermal energy disrupts zone formation, eliminating magnetism. The Curie point for iron is near austenite's stability range, but heating ferrite or quenching austenite above the Curie point also removes magnetism, demonstrating it is a temperature not phase effect.
Metal Forming & Shaping: Lecture Introduction
The document introduces metal forming processes. It defines metal forming as shaping metallic materials through plastic deformation, where the shape changes permanently in contrast to elastic deformation. It describes bulk deformation processes as involving large plastic deformation without changing volume. These include hot working like forging above the recrystallization temperature for easier forming, and cold working like rolling at room temperature for better accuracy. Sheet forming processes change the shape but not the cross-section, operating on thin metal sheets using stamping presses.
Fracture Mechanics & Failure Analysis: creep and stress rupture
Fracture Mechanics & Failure Analysis: creep and stress ruptureNED University of Engineering and Technology
The document discusses creep and stress rupture behavior of materials at high temperatures. It provides an introduction to creep and stress rupture tests, describing the three stages of creep curves and how applied stress and temperature affect creep behavior. Different deformation mechanisms at high temperatures are discussed, including dislocation glide/creep, diffusion creep, and grain boundary sliding. The document also covers topics such as structural changes during creep, superplasticity, and fracture modes at elevated temperatures.Fracture Mechanics & Failure Analysis: Lecture Mechanism of Creep in Metal
Fracture Mechanics & Failure Analysis: Lecture Mechanism of Creep in Metal NED University of Engineering and Technology
There are three main mechanisms that contribute to creep in metals:
1) Dislocation slip and climb, where dislocations move through the crystal lattice with the aid of vacancies allowing them to climb past obstacles.
2) Grain boundary sliding, where shear stresses cause grain boundaries to slide past one another.
3) Diffusional flow, where atoms diffuse from high stress areas to low stress areas within grains or along grain boundaries, elongating the material. Each mechanism involves the thermally activated movement of vacancies within the metal.More from NED University of Engineering and Technology (20)
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AI for Legal Research with applications, tools
AI applications in legal research include rapid document analysis, case law review, and statute interpretation. AI-powered tools can sift through vast legal databases to find relevant precedents and citations, enhancing research accuracy and speed. They assist in legal writing by drafting and proofreading documents. Predictive analytics help foresee case outcomes based on historical data, aiding in strategic decision-making. AI also automates routine tasks like contract review and due diligence, freeing up lawyers to focus on complex legal issues. These applications make legal research more efficient, cost-effective, and accessible.
一比一原版(osu毕业证书)美国俄勒冈州立大学毕业证如何办理
原版一模一样【微信：741003700 】【(osu毕业证书)美国俄勒冈州立大学毕业证成绩单】【微信：741003700 】学位证，留信认证（真实可查，永久存档）原件一模一样纸张工艺/offer、雅思、外壳等材料/诚信可靠,可直接看成品样本，帮您解决无法毕业带来的各种难题！外壳，原版制作，诚信可靠，可直接看成品样本。行业标杆！精益求精，诚心合作，真诚制作！多年品质 ,按需精细制作，24小时接单,全套进口原装设备。十五年致力于帮助留学生解决难题，包您满意。
本公司拥有海外各大学样板无数，能完美还原。
1:1完美还原海外各大学毕业材料上的工艺：水印，阴影底纹，钢印LOGO烫金烫银，LOGO烫金烫银复合重叠。文字图案浮雕、激光镭射、紫外荧光、温感、复印防伪等防伪工艺。材料咨询办理、认证咨询办理请加学历顾问Q/微741003700
【主营项目】
一.毕业证【q微741003700】成绩单、使馆认证、教育部认证、雅思托福成绩单、学生卡等！
二.真实使馆公证(即留学回国人员证明,不成功不收费)
三.真实教育部学历学位认证（教育部存档！教育部留服网站永久可查）
四.办理各国各大学文凭(一对一专业服务,可全程监控跟踪进度)
如果您处于以下几种情况：
◇在校期间，因各种原因未能顺利毕业……拿不到官方毕业证【q/微741003700】
◇面对父母的压力，希望尽快拿到；
◇不清楚认证流程以及材料该如何准备；
◇回国时间很长，忘记办理；
◇回国马上就要找工作，办给用人单位看；
◇企事业单位必须要求办理的
◇需要报考公务员、购买免税车、落转户口
◇申请留学生创业基金
留信网认证的作用:
1:该专业认证可证明留学生真实身份
2:同时对留学生所学专业登记给予评定
3:国家专业人才认证中心颁发入库证书
4:这个认证书并且可以归档倒地方
5:凡事获得留信网入网的信息将会逐步更新到个人身份内，将在公安局网内查询个人身份证信息后，同步读取人才网入库信息
6:个人职称评审加20分
7:个人信誉贷款加10分
8:在国家人才网主办的国家网络招聘大会中纳入资料，供国家高端企业选择人才
办理(osu毕业证书)美国俄勒冈州立大学毕业证【微信：741003700 】外观非常简单，由纸质材料制成，上面印有校徽、校名、毕业生姓名、专业等信息。
办理(osu毕业证书)美国俄勒冈州立大学毕业证【微信：741003700 】格式相对统一，各专业都有相应的模板。通常包括以下部分：
校徽：象征着学校的荣誉和传承。
校名:学校英文全称
授予学位：本部分将注明获得的具体学位名称。
毕业生姓名：这是最重要的信息之一，标志着该证书是由特定人员获得的。
颁发日期：这是毕业正式生效的时间，也代表着毕业生学业的结束。
其他信息：根据不同的专业和学位，可能会有一些特定的信息或章节。
办理(osu毕业证书)美国俄勒冈州立大学毕业证【微信：741003700 】价值很高，需要妥善保管。一般来说，应放置在安全、干燥、防潮的地方，避免长时间暴露在阳光下。如需使用，最好使用复印件而不是原件，以免丢失。
综上所述，办理(osu毕业证书)美国俄勒冈州立大学毕业证【微信：741003700 】是证明身份和学历的高价值文件。外观简单庄重，格式统一，包括重要的个人信息和发布日期。对持有人来说，妥善保管是非常重要的。
一比一原版(uofo毕业证书)美国俄勒冈大学毕业证如何办理
原版一模一样【微信：741003700 】【(uofo毕业证书)美国俄勒冈大学毕业证成绩单】【微信：741003700 】学位证，留信认证（真实可查，永久存档）原件一模一样纸张工艺/offer、雅思、外壳等材料/诚信可靠,可直接看成品样本，帮您解决无法毕业带来的各种难题！外壳，原版制作，诚信可靠，可直接看成品样本。行业标杆！精益求精，诚心合作，真诚制作！多年品质 ,按需精细制作，24小时接单,全套进口原装设备。十五年致力于帮助留学生解决难题，包您满意。
本公司拥有海外各大学样板无数，能完美还原。
1:1完美还原海外各大学毕业材料上的工艺：水印，阴影底纹，钢印LOGO烫金烫银，LOGO烫金烫银复合重叠。文字图案浮雕、激光镭射、紫外荧光、温感、复印防伪等防伪工艺。材料咨询办理、认证咨询办理请加学历顾问Q/微741003700
【主营项目】
一.毕业证【q微741003700】成绩单、使馆认证、教育部认证、雅思托福成绩单、学生卡等！
二.真实使馆公证(即留学回国人员证明,不成功不收费)
三.真实教育部学历学位认证（教育部存档！教育部留服网站永久可查）
四.办理各国各大学文凭(一对一专业服务,可全程监控跟踪进度)
如果您处于以下几种情况：
◇在校期间，因各种原因未能顺利毕业……拿不到官方毕业证【q/微741003700】
◇面对父母的压力，希望尽快拿到；
◇不清楚认证流程以及材料该如何准备；
◇回国时间很长，忘记办理；
◇回国马上就要找工作，办给用人单位看；
◇企事业单位必须要求办理的
◇需要报考公务员、购买免税车、落转户口
◇申请留学生创业基金
留信网认证的作用:
1:该专业认证可证明留学生真实身份
2:同时对留学生所学专业登记给予评定
3:国家专业人才认证中心颁发入库证书
4:这个认证书并且可以归档倒地方
5:凡事获得留信网入网的信息将会逐步更新到个人身份内，将在公安局网内查询个人身份证信息后，同步读取人才网入库信息
6:个人职称评审加20分
7:个人信誉贷款加10分
8:在国家人才网主办的国家网络招聘大会中纳入资料，供国家高端企业选择人才
办理(uofo毕业证书)美国俄勒冈大学毕业证【微信：741003700 】外观非常简单，由纸质材料制成，上面印有校徽、校名、毕业生姓名、专业等信息。
办理(uofo毕业证书)美国俄勒冈大学毕业证【微信：741003700 】格式相对统一，各专业都有相应的模板。通常包括以下部分：
校徽：象征着学校的荣誉和传承。
校名:学校英文全称
授予学位：本部分将注明获得的具体学位名称。
毕业生姓名：这是最重要的信息之一，标志着该证书是由特定人员获得的。
颁发日期：这是毕业正式生效的时间，也代表着毕业生学业的结束。
其他信息：根据不同的专业和学位，可能会有一些特定的信息或章节。
办理(uofo毕业证书)美国俄勒冈大学毕业证【微信：741003700 】价值很高，需要妥善保管。一般来说，应放置在安全、干燥、防潮的地方，避免长时间暴露在阳光下。如需使用，最好使用复印件而不是原件，以免丢失。
综上所述，办理(uofo毕业证书)美国俄勒冈大学毕业证【微信：741003700 】是证明身份和学历的高价值文件。外观简单庄重，格式统一，包括重要的个人信息和发布日期。对持有人来说，妥善保管是非常重要的。
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Case study: Failure Analysis of LPTR blade
- 1. CASE STUDY Failure of a Low-Pressure Turbine Rotor (LPTR) Blade Dr. Muhammad Ali Siddiqui
- 2. Content Background with literature review about super alloys, properties, alloy design and manufacturing process Testing Procedure and Results Visual Examination of General Physical Features Scanning Electron Microscopy and Fractography Metallography and Hardness Discussion Conclusion 2
- 3. Background and Literature Review 3
- 4. • Fracture: low-pressure turbine blade causing extensive damage to the Jet engine. 4
- 5. 5
- 6. 6
- 8. 8
- 9. 9
- 10. 10
- 11. 11
- 12. 12
- 13. 13 Ni
- 14. 14 Ni Al Ni Al Thermodynamic favour ordered structure
- 15. 15
- 16. 16 70% of intermetallic make it suitable for applications
- 19. 19
- 20. 20
- 21. 21
- 22. 22 Investment (lost wax) casting Materials 2019, 12(11), 1781; https://doi.org/10.3390/ma12111781
- 23. 23
- 24. 24
- 25. 26 ceramic topcoat is deposited by electron beam physical vapor deposition (EBPVD) or air plasma- spraying (APS) Sandwiched between the topcoat and the metallic bond coat is the thermally grown oxide (TGO) Surface treated: THERMAL-BARRIER COATINGS (TBCs) Examples: Aluminide coatings
- 26. 27 First stage (the stage directly following the combustor) of a modern gas turbine faces temperatures around 1,370 °C Modern military jet engines, like the Snecma M88, can see turbine temperatures of 1,590 °C. Cross sectional view
- 27. 28
- 28. 29
- 29. Case Study 30
- 30. LPTR blade failed Ni-base superalloys causing extensive damage to the engine. 31 Background
- 31. Visual Examination 32 Observation: •Fractured = Airfoil section at a distance of about 25 mm from the blade root platform •The fracture surface was flat and perpendicular to the blade axis. Fig : Photograph of the failed LPTR blade
- 32. Low magnification Examination 33 Fig : Entire fracture surface Observation: Discolored due to oxidation and exposure to high temperatures well-defined crescent-shaped area with smooth fracture features Fatigue features Fatigue crack found at leading edge. Remaining fracture surface had a crystalline appearance
- 33. 34 Intergranular = 1 mm from the leading edge Transgranular = 11 mm SEM and Fractography Fig: Intergranular fracture at the leading edge Fig: Beach Marks Fig: striations
- 34. 35 Metallography and Hardness Fig: Microstructure at leading edge Fig: Microstructure at midcord Observation: precipitates dissolution at the leading edge. At the leading edge 350 HV At the mid-chord section 400 HV
- 35. Discussion 1. Failure Mechanism: • Intergranular mode (IM) to about 1 mm from the leading edge • Followed by a transgranular mode (TM) of about 11 mm – IM Principal mode in high-temperature creep/stress rupture. – Cracking occur principally along the grain boundaries normal to the major stress axis of the blade. – TM The incremental crack growth is evidenced by the presence of closely spaced striations. 36
- 36. • Therefore, it appears that the crack initiated at the leading edge of the blade by stress rupture and propagated fast to a distance of about 1 mm. • In the second stage, this crack acted as a notch for stress concentration and led to the propagation of the crack by fatigue. • The fatigue crack then propagated progressively up to about 11 mm from the leading edge before giving way to overload fracture. 37 Cont…
- 37. 2. Cause of Failure: • Dissolution of gamma prime (γ-prime) precipitates at the leading edge clearly indicates that the blade was exposed to high temperatures the hardness the creep resistance of the blade drastically. 38
- 38. Conclusion • The cracking of the blade took place by stress rupture. • Once the initial crack had formed due to stress rupture, the crack further propagated under the cyclic loading experienced by the blade during service. • The factors responsible for such cracking are high operating temperatures and stresses that causes the dissolution of the precipitates. 39
- 39. Thank You 40