Dissertations / Theses on the topic 'Blades Of Steel'

Power generation in thermal stations typically relies on large steam turbines. The corrosion resistant steel blades used in the last stage of a typical low pressure rotor set are approximately 1m long and experience high centrifugal loading during service. They operate in a wet steam environment, at approximately 60°C while rotating at 3000rpm, and failure modes include high and low cycle fatigue, stress corrosion cracking or corrosion fatigue. The blades are retained by a fir tree root which is normally shot-peened to generate compressive residual stresses that resist crack initiation. Finite element (FE) modelling has indicated that, in the absence of shot-peening, stresses above yield are induced at the fir tree root during operation. In a shot-peened blade these lead to relaxation of the shot peening residual stresses. To date, no systematic information has been obtained on the level of residual stresses induced in the fir tree by shot-peening and their subsequent relaxation during service loading, nor are there any guidelines as to the magnitude of residual stresses necessary to ensure integrity of the turbine over a life span of at least twenty years. At least one of these blades has suffered catastrophic failure in recent years causing severe damage, in excess of €100M, to the turbine-generator set on a South African power station [1]. This thesis reports results from a comprehensive program of residual stress measurements at the shot-peened fir tree roots of service blades, and in specimens that simulate the root conditions, using diffraction data from laboratory and synchrotron X-ray radiation (SXRD). Shot-peening coverage between 75% and 200% was used and stresses were measured over a depth of 5mm into the blades/specimens. Measurements were made in the as-peened condition and after applying cyclic stresses representative of overspeed proof testing and of service operation. The results were used to calibrate FE modelling of residual stresses and as input into fatigue life prediction.

An investigation has been undertaken to examine the effect of microstructure on the mechanical properties of FV520B, a precipitation hardenable martensitic stainless steel. This high performance grade of stainless steel was heat treated to three commercially available material specifications, namely the peak hardened, standard and softened overaged conditions. These three precipitation hardened conditions were found to exhibit a range of tensile properties. In order to determine the role of the microstructure, a full materials characterisation programme was performed. The investigative techniques used to characterize the microstructures, were Transmission Electron Microscopy (TEM); Analytical Scanning Electron Microscopy (ASEM); optical microscopy; dilatometry and X-Ray Diffraction (XRD). The microstructural phases and features identified were measured and quantified wherever possible. The effect of the material microstructure and environment on the fatigue properties of FV520B have been investigated. Fatigue tests were performed under uniaxial loading conditions at a stress ratio R (omin/omax) of -1. The tests were undertaken using highly polished specimens to determine the fatigue strength of the three precipitation hardened conditions. The test conditions employed were air and a corrosive 3.5% sodium chloride environment, at pH2 and ambient temperature. The role of the microstructure and the effectiveness of the tensile strengthening mechanisms on the fatigue and corrosion fatigue strength have been discussed. Using SEM, the fatigue crack nucleation mechanisms prevalent within the three microstructures in air and the chloride environment have also been identified. For the peak hardened material, nonmetallic inclusions dominated the fatigue crack nucleation process in air and chloride environments. For the softened overaged condition, multiple site nucleation due to slip band cracking was the prevalent mechanism especially at higher nominal stress amplitudes. The tolerance of this high strength material to small defects at higher stress levels and the actual size of the critical microstructural defects initiating failure have also been highlighted. The microstructure has been shown to strongly influence the processes of fatigue crack nucleation, Stages I and II crack propagation and the concept of the microstructure acting as barriers and providing resistance to crack growth have been discussed. The effectiveness and the size of these microstructural barriers to crack growth have been considered. This discussion has led to the proposal of a model that facilitates flow stress and fatigue lifetime predictions as a function of the quantity of a key microstructural phase. The key microstructural phase, namely reverted austenite affected both the tensile and fatigue properties of FV520B as a function of the heat treatment. The standard overaged material was found to exhibit the greatest resistance to fatigue crack propagation.

Stress corrosion cracking (SCC) is a corrosion phenomenon which continues to plague the power generating industry especially in low pressure (LP) steam turbine blades operating in the phase transition zone. An investigation has therefore been conducted to examine the effect of heat treatment condition on the microstructure, mechanical properties and SCC properties of one such LP turbine blade material, FV520B, used in the steam turbines of coal-fired power stations in South Africa. The three stage heat treatment cycle of the FV520B turbine blades consists of homogenisation at 1020°C for 30 minutes, solution treatment at 790°C for two hours and precipitation hardening at 545°C for six hours. In this study, the precipitation hardening temperature was varied in the range 430-600°C to investigate how this variation would affect the material and SCC properties. Hardness and tensile testing were performed to obtain mechanical properties while the investigative techniques used to characterise the microstructures were light microscopy, dilatometry, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Stress corrosion susceptibility for the different heat treatment conditions was quantified using U-bend specimens while crack growth rates and threshold stress intensities for SCC (KISCC) were measured using fatigue precracked wedge open loaded (WOL) specimens. Both SCC tests were conducted in a 3.5% NaCl environment maintained at 90°C. XRD results revealed the presence of reverted austenite in the higher tempered specimens due to the precipitation hardening temperature being close to the Ac1 temperature for the material. The presence of reverted austenite was shown to adversely affect mechanical strength and hardness which decreased with increasing precipitation hardening temperature. Light and electron microscopy (SEM and TEM) revealed the presence of Cr-rich precipitates along the prior austenite grain boundaries in all tested heat treatment conditions. The propensity, quantity and size of the Cr-rich precipitates increased as the specimen temper temperature increased. SCC susceptibility was shown to be dependent upon yield strength and decreased as precipitation hardening temperature increased with specimens in the overaged condition showing no cracking after more than 5000 hours in the test environment. WOL testing only produced cracking in the three highest strength specimens after 2000 hours. Crack growth rates and threshold stress intensities were found to be dependent on yield strength and decreased with increasing precipitation hardening temperature. Analysis of fracture surfaces revealed crack propagation along prior austenite grain boundaries in all test heat treatment conditions indicating intergranular stress corrosion cracking (IGSCC) as the dominant cracking mechanism.

The following thesis is a study on the ability to create acceptable welds in thin-plate, ultra-high-strength steels (UHSS) by way of friction stir welding (FSW). Steels are welded together to create tailor-welded blanks (TWB) for use in the automotive industry. Dual Phase (DP) 590, 780, and 980 steel as well as Transformation-Induced Plasticity (TRIP) 590 steel with thicknesses ranging from 1.2 mm to 1.8 mm were welded using friction stir welding under a variety of processing conditions, including experiments with dissimilar thicknesses. Samples were tested under tensile loads for initial determination if an acceptable weld had been created. Acceptable welds were created in both TRIP 590 and DP 590 at speeds up to 102 centimeters-per-minute. No acceptable welds were created in the DP 780 and DP 980 materials. A series of microhardness measurements were taken across weld samples to gain understanding as to the causes of failure. These data indicate that softening, caused by both excessive heat and insufficient heat can result in weld failure. Not enough heat causes the high concentration of martensite in these materials to temper while too much heat can cause excessive hardening in the weld, through the formation of even more martensite, which tends to promote failure mode during forming operations. Laser welding is one of the leading methods for creating tailor-welded blank. Therefore, laser welded samples of each material were tested and compared to Friction Stir Welded samples. Lower strength and elongation are measured in weld failure while the failure location itself determines the success of a weld. In short, an acceptable weld is one that breaks outside the weld nugget and Heat Affected Zone (HAZ) and where the tensile strength (both yield and ultimate) along with the elongation are comparable to the base material. In unacceptable welds, the sample broke in the weld nugget or HAZ while strength and elongations were well below those of the base material samples.

Shear blades are mostly made of cold-work tool steels and manufactured by rolling process. Rolling process is performed not only for forming the tool but also for improving the mechanical properties. In this study, an alternative method, involving sand casting, hot forging and heat treatment processes to manufacture the shear blades, has been proposed. In the proposed method, plastic deformation will be carried out by means of forging instead of rolling. The material has been selected as X48CrMoV8-1. For both of casting and forging processes, simulations have been conducted by using Computer Aided Engineering Software. According to the results of casting process simulation, the billets have been poured. These billets have been soft annealed first and then taken as the initial raw material for the forging process. After the forging process, quenching and tempering processes have been applied. The specimens have been taken as cast, as forged and as tempered and the microstructural analysis and mechanical tests have been performed on these. The same tests and analysis have been repeated for a commercially available shear blade sample which is manufactured by rolling. All these investigations have shown that the properties of the forged shear blade are very similar to the rolled shear blade. Therefore, the new proposed method has been verified to be used as an alternative manufacturing method for the cold-work tool steel shear blades.

Diploma theses is focused on welding experiment of maraging steel by use Yb-YAG laser. Experimet is based on testing of combination steel 11321 and maraging steel. Domex420MC, Domex720MC a QSE380. In theoretical part there are described laser technology of welding, weld defect, maraging steel and inspection of welded joints. In experimental part there are porposed test and made mechanical test of weld as transverse tensile test, bend tests, Erichsen cupping test, Vickers hardness test and makroscopic and microscopic examination of welds. In conclusion there are analysis of the experiment results.

The master's thesis presents an experiment of welding of high strength steel Docol 1200 M and of steel DC01 by the fiber Yb-YAG laser. The experiment is based on testing welds which were made during the experiments. The lasers, laser technologies of welding, steels of higher strength, tailored blanks technology and testing of welds are described in the theoretical part. The practical part contains description and evaluation of tests of welds – transverse tension test, Vickers hardness test, Erichsen cupping test and macrostructure and microstructure test. The final evaluation results of the experiment are presented in the conclusion of the master's thesis.

The flow pattern has widely been recognized to have an impact on the exogenous non-metallic inclusion generation in the gating system and mold flux entrapment in the uphill teeming process. Thus, a well-controlled flow pattern during the teeming process can improve the quality of ingots and further increase the yield during steel production. The current study focused on investigating and optimizing the flow pattern of steel in the gating system and molds to improve steel cleanliness during the initial filling moment. A mathematical model considering a trumpet was initially compared to a reduced model only considering part of the runner channel. Thereafter, the influence of swirl blades implemented at the bottom of the vertical runner on the improvement of initial filling conditions in the molds was investigated in a model considering the entire mold system including a trumpet. The effects of a swirl blade orientation on a swirling flow were further discussed. The simulation results, when utilizing swirl blades, were also verified by plant trials performed at Scana Steel. In addition, a new novel swirling flow generation component, TurboSwirl, was studied in a model considering the entire mold system including a trumpet. The model was based on modifications of the refractory geometry at the elbow of the runners near the mold without the usage of an inserted flow control device in the gating system. Owing to its great potential for improving the flow pattern of steel during the initial filling moment, the effect of TurboSwirl on steel cleanliness was also studied. The results showed that the initial filling conditions during the uphill teeming process can be improved by using a swirl blade or a TurboSwirl in the gating system. This makes it possible to further decrease the initial position of mold powder bags. In addition, it reduces the possibilities of exogenous non-metallic inclusion generation in the gating system as well as mold flux entrapment in the mold during the uphill teeming process. However, the utilization of swirl blades created a considerable amount of droplets when steel entered the molds during the first couple of seconds, which also was verified by the plant trials. The introduction of TurboSwirl showed a greater potential than a swirl blade due to a more evenly distributed swirling flow. The DPM model adopted in the simulations revealed that the TurboSwirl can improve steel cleanliness by increasing the non-metallic inclusion collision rate both with respect to Stokes and turbulent collisions.

QC 20130204

This thesis is focused on laser welding and hybrid laser-TIG welding. The first part contains a brief theoretical description of these technologies. Standard quality and plasticity tests of welded joint are also mentioned. The second, experimental part, centres on the study of plasticity of tailored blanks (made of different types of HSLA steel), that are welded with laser and laser-TIG technology. The aim of the thesis is to assess process parameters effect on weld suitability for following deep drawning operation. Based on the calculated and measured figures obtained from the experiment, the most suitable welding parameters were chosen.

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Os aços ferramenta têm uma importante participação no mercado mundial no que se refere a engenharia. São usados na indústria metal-mecânica como ferramentas de corte, moldes, punções, entre outras aplicações. Devido a sua grande importância, é imprescindível discutir a relação entre a microestrutura e as propriedades mecânicas, devido ser uma prática comum na indústria especificar os tratamentos térmicos com base principalmente na dureza final do material, sem considerar que para um mesmo valor de dureza um aço ferramenta pode apresentar diferentes propriedades mecânicas, isto dependendo do ciclo de tratamento térmico aplicado. Logo, a seleção do tratamento térmico é um aspecto tecnológico relevante no desempenho destes aços. Tendo em vista a vasta possibilidade de propriedades mecânicas obtidas (tenacidade a fratura) com diferentes tratamentos térmicos, esse trabalho teve como objetivo especificar um aço ferramenta nacional e um conjunto de parâmetros de tratamento térmico que possibilite a utilização deste material como forma de substituição de um outro aço importado utilizado na confecção de lâminas de corte usadas no processamento de placas de chumbo. O aço selecionado para o desenvolvimento deste trabalho foi o aço AISI D6, a seleção desse aço foi feita tomando-se como base as características obtidas através de análises realizadas em campo e de microdureza e microestrutura das lâminas de corte já existentes no processo confeccionadas com aço importado. Com o aço selecionado em mãos, aplicou-se dois tratamentos térmicos diferentes de têmpera e revenido (um proposto pelo fabricante e outro proposto pelo trabalho em execução), onde avaliou-se o efeito dos tratamentos térmicos sobre as propriedades mecânicas e microestrutural do material. Através da análise dos resultados da relação entre dureza e tenacidade, constatou-se que para os dois tratamentos térmicos aplicados, não houve variações significativas das propriedades mecânicas do material, e que os dois tratamentos apresentaram resultados satisfatórios. O aço ferramenta nacional especificado apresentou-se como alternativa para substituição do aço importado utilizado atualmente. Testes obtidos em campo com a lâmina fabricada com o aço nacional especificado nesse estudo e que recebeu o tratamento térmico proposto pelo fabricante (FAB), corroboraram com a análise das propriedades, visto que se constatou aumento do tempo de vida de corte em mais de 30%.
The tool steels have an important participation in the world market with regard to engineering. They are used in the metal-mechanic industry as cutting tools, molds, punches, among other applications. Because of its great importance, it is essential to discuss the relationship between the microstructure and the mechanical properties, since it is a common practice in industry to specify thermal treatments based mainly on the final hardness of the material, without considering that for a same hardness value a steel tool may have different mechanical properties, depending on the heat treatment cycle applied. Therefore, the selection of heat treatment is a relevant technological aspect in the performance of these steels. Considering the wide possibility of mechanical properties obtained (fracture toughness) with different thermal treatments, this work had the objective of specifying a national tool steel and a set of thermal treatment parameters that allow the use of this material as a substitute for a another imported steel used in the manufacture of cutting blades used in the processing of lead plates. The steel selected for the development of this work was AISI D6 steel, the selection of this steel was made taking as a base the characteristics obtained through field analysis and microhardness and microstructure of the cutting blades already in the process made with steel imported. With the selected steel in hand, two different tempering and tempering treatments were applied (one proposed by the manufacturer and another proposed by the work in progress), where the effect of the thermal treatments on the mechanical and microstructural properties of the material was evaluated. By analyzing the results of the relationship between hardness and toughness, it was found that for the two thermal treatments applied, there were no significant variations of the mechanical properties of the material, and that both treatments presented satisfactory results. The specified national steel tool was presented as an alternative to replace the currently used imported steel. Field tests with the blade manufactured with the national steel specified in this study and that received the thermal treatment proposed by the manufacturer (FAB), corroborated with the analysis of the properties, as it was observed an increase in the cutting life time in more than 30 %.

碩士
國立成功大學
機械工程學系
88
Analysis and Simulation of Process Parameters for Forging of Stainless Steel Turbine Blades Kun-Hwa Chen* Rong-Shean Lee** Department of Mechanical Engineering National Cheng Kung University Tainan, Taiwan, R.O.C. Abstract The computer-aided engineering (CAE) has been widely used since the development of the finite element analysis and the rapid progress of the computer technology. For most computer-aided forging process development, process variables, such as stress, strain rate, temperature and load are analyzed, however, the microstructure of the workpiece cannot be obtained until the part has been produced physically. To make the computer-aided engineering environment more complete, method for predicting microstructure is needed. The purpose of this research is to simulate the forging process and predict the microstructure of the final product by observing the microstructure of the test specimens. To make sure that the parameters in the roll forging and upset forging processes simulations are correct, the results from heat transfer experiments, isothermal and non-isothermal ring compression and cylinder compression tests were compared with the simulation results. By calculating the Zener-Hollomon parameters of the observed specimen, a microstructure database was created. To construct the rule for predicting microstructure, the simulated Zener-Hollomon parameter (Z value) distributions of the rolled and upset workpiece were computed from the temperature and strain rate distributions and mapped to the microstructure of the forged part. Comparing the microstructure-Z value map with the microstructures of the test specimens, the rule for predicting microstructure was constructed. There are two major contributions in the proposed research:(1) the relationship between activation energy and precipitation of carbide is identified (2) by comparing the simulated Zener-Hollomon parameters with those from experiment. The microstructure of the workpiece can be predicted and thus reducing the manufacturing lead time and cost. In the future, virtual forging engineering system can be constructed based on the proposed microstructure prediction method. *Author **Advisor

碩士
國立屏東科技大學
機械工程系所
106
Turbine blades are crucial engine components that operate in harsh environments with high temperatures and complex stress conditions. The performance levels of turbine blades (particularly their resistance to high temperatures) are considered to be important indicators of how advanced an engine is, and in a certain sense, they can also represent the industrial standards of a nation. Investment casting offers processing characteristics that conventional sand casting, forging, and mechanical cutting do not, is suitable for a wide range of materials, and enables flexible manufacturing, especially for components with hollow cavities or complex internal or external structures. The use of investment casting can reduce costs while enhancing workpiece precision, and for these reasons, we adopted investment casting to develop a casting scheme for turbine blades. Operating in harsh environments for long periods of time increases the chance of cavitation and creeping in the surface structures of turbine blades, which severely affects their service live. As a result, the shrinkage and porosity defects in turbine blade workpieces must be completely eliminated. Using mold flow analysis, this study developed a casting scheme for turbine blades comprising SCH12 heat-resistant steel. Predictions of the shrinkage pores and cavities and blow hole defects in the turbine blade structure were made based on simulations of the flow field evolutions in the mold cavity during casting and observation of the solidification process. Revisions were then made to the gating system based on the causes of defect formation. The simulation results indicate that soaking the bottom of the gating system can enhance the cooling rate of the workpieces. A soaking depth of 13 mm resulted in the optimal solidification directions from the outside inward and from the bottom up, which produced good feeding effects, reduced the generation of isolated residual melt, increased workpiece quality, and extended the service life of the turbine blades.

碩士
國立臺灣大學
機械工程學研究所
107
Due to the need of different functions, make part of automobiles structures has to been designed more thicker to reinforce the strength of the automobiles body. This method will not only increase the weight of automobiles, but also increase the cost of processing and material. To overcome these problems, Tailor-Welded Blank was then be invented. Tailor-Welded Blank(TWB) means two or above kind of materials being welded to become one blank. Now most of the TWB is been welded by laser, which has feature of low manufacturing cost and high accuracy, even more, TWB can be designed flexibly to correspond function, which means only use the specific material on the very need part of automobiles structure, can reduce the usage of steel and then reduce the weight of automobile. More and more manufactory are using this technic. However, TWB has two (or above) kinds of material, which means it has two different properties, in the progression of stamping will encounter much of difficulties, such as two different springback and fracture easily. This thesis aims at researching how to overcome these problems based on CAE simulations. Variable blank holder force and draw bead will be applied to eliminate side curl. In addition, in order to discuss the impact of weld line’s properties on metal forming and CAE simulation, the experiment of weld line’s mechanical properties will be verified.

The Steel Merchant offers a service of stocking and distributing steel products and value added services throughout Africa. The company is the largest steel merchant in Africa employing over 5500 employees. The South African government implemented the Employment Equity Act, No 55, (1998) and Broad-Based Black Economic Act, No 53, (2003) to readdress the discrimination of the past and create fair opportunities for Previously Disadvantaged Individuals (PDI) in the workplace. The Steel Merchant's business environment is severely affected by these legislations and is required to comply with the provisions of the Act or will receive fines and penalties. Since the Acts inception the merchant continues to struggle in recruiting and retaining PDIs in professionally qualified and management positions. The organization has experienced strategic drift by falling from a Black Economic Empowerment (BEE) Procurement Recognition/Status Level of 5 down to level 6. The research identified various factors within the organization that are hindering its overall ability to adapt and progress in terms of Employment Equity (EE) and BEE. The study is focused on identifying the internal and external barriers that prevent the effective implementation of BEE and EE strategies in order to recruit and retain previously disadvantaged professionals at the Steel Merchant. The Research Objectives are: • To evaluate the effect of organizational culture and climate on the implementation of Employment Equity, Affirmative Action (AA) and BEE Strategies • To analyze the importance of Human Resource Management (HRM) in the development of recruitment and retention strategies of previously disadvantaged professionals • To investigate the differences in gender and race leadership qualities and behavior • To identify and assess the barriers in implementing employment equity recruitment and retention strategies • To determine how government legislation will influence the Steel Organizations' competitiveness internationally Internal secondary data was used to analyze the Merchant's Human Resource Management, EE and BEE performance. External secondary data from the South African government departments was used to analyze the legislative Acts and how the company performs compared to the industry standards. A quantitative research approach was followed in the investigation. A questionnaire was developed using closed-ended questions to obtain information related to the respondent's demographical background as well as their opinion on each objective. The questionnaire was distributed by email to 1 00 employees and weighted according to racial group (Black, White, Coloured and Asian) and gender (Male and Female). The method allowed the researcher to receive and analyze the information quickly at no financial cost. Descriptive statistics were used to interpret the results and describe the behaviour of each racial and gender group contained in the sample. The data methods used were: • Percentages • The mean, mode and median • Standard Deviation The conclusions from the sample were used to generalize about the steel merchant population whilst research from recognized academics was utilized to authenticate and substantiate the research findings improving the accuracy and reliability of the research. The results of the study identified the following factors have contributed to the merchant's inability to recruit and retain PDI at professionally qualified and management levels: • The Steel Merchant has a white male dominated organizational culture and ineffective HRM strategies • Black shareholders have contributed little towards previously disadvantaged development creating resentment by employees • Employment Equity, Black Economic Empowerment and Affirmative action has created racial divides, a lack of trust and will negatively influence the company's competitiveness internationally. The research identified various problems that hinder the implementation of EE and BEE policy at the steel merchant which makes it difficult to recruit and retain talented PDI. The following recommendations have been made to minimize resistance and integrate EE and BEE policies to improve recruitment and retention in the organization: • Define and communicate the BEE/EE vision and strategy • Delayer hierarchal levels • National Culture Training • Implement Performance Management Systems • lncentivize Knowledge Sharing • Re-evaluate the recruitment policies • Train, develop and mentor PDI • Develop career paths and succession plans • Create a leadership development program • Create a shared understanding of EE • Address white fears through empowerment • Black shareholders should be actively involved with the development of PO employees • Harness African culture to succeed internationally. EE and BEE is obligatory and will inevitably influence the company's performance. The Steel Merchant has the resources and capabilities to eliminate resistance and implement effective HRM strategies to recruit and retain talented POl in professional and management positions. By achieving this objective, the company's Broad Based Black Employment Equity (BBBEE) rating will advance resulting in a sustainable competitive advantage and more business opportunities in the future.
Graduate School of Business Leadership
M.B.A.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering, under the supervision of Professor Claudia Polese,2018
The root section of a turbine blade is the most critical part as it forms the structural bond of the turbine blade to the shaft. If not maintained correctly the blade could fail catastrophically due to high and low cycle fatigue, stress corrosion cracking as well as corrosion fatigue. The sources of loading on the blades vary from normal operation, excitation of natural frequencies during transient occasions and overloads during statutory testing. Different surface modification technologies can be put in place to improve blades in-service performance. The present study is aimed at comparing previous results achieved from Shot Peening (SP) of an equivalent turbine blade to those achieved by Laser Shock Peening without coating (LSPwC).The SP data which is used for comparison is from the work and study done to optimise the SP of a 12Cr steel steam turbine blade. It is expected that LSPwC processing of the blade will result in a reduction in mean surface roughness (Ra), and deeper compressive residual stresses than the conventional SP processing. The focus of this investigation is also to determine the effects of LSPwC laser and processing parameters, such as laser intensity, laser spot size, coverage, water layer, and possibly laser wavelength on the X12CrNiMo12 high strength steel target material. Segments of an ex-service turbine blade, 20x20mm by 10mm thickness, processed at the CSIR National Laser Centre under various LSPwC parameters were analysed as follows: composition properties confirmed by spark tests; surface integrity assessed by SEM and 3D roughness mapping; microstructure; residual stress measurements by laboratory X-ray Diffraction. The experimental results helped in optimizing the LSPwC parameters for the X12CrNiMo12, before applying LSPwC to the more complex geometry of the blade root. This study then allowed for the determination of which peening process is most suited for turbine components.
XL2019