Study of wear mechanism of contact surfaces of steam turbine blades made of titanium VT6 alloy

2021 ◽  
pp. 81-89
Author(s):  
A.M. Zolotov ◽  
M.O. Smirnov ◽  
T.A. Chizhik
Keyword(s):  
Mechanical Properties ◽  
Steam Turbine ◽  
Wear Mechanism ◽  
Turbine Blades ◽  
Microstructural Analysis ◽  
X Ray ◽  
Different Types ◽  
Steam Turbine Blades ◽  
Contact Surfaces

The contact surfaces of the banding shelves of adjacent steam turbine blades made of titanium VT6 alloy after operation are studied by fractography, micro-X-ray and microstructural analysis and determination of mechanical properties. The different types of destruction of the contact surfaces are analyzed and explained. It is shown that the reason for intensive abrasion of the turbine blades' binding meshes is violation of the welding mode in the station conditions.

Brazed coatings for steam turbine blades: impact of the tape architecture and composition on mechanical properties

2020 ◽  
Vol 111 (11) ◽  
pp. 916-922
Author(s):  
K. Bobzin ◽  
W. Wietheger ◽  
J. Hebing ◽  
L. Gerdt ◽  
H. Krappitz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Steam Turbine ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Turbine Blades ◽  
Surface Hardness ◽  
Three Point Bending ◽  
Wear And Corrosion ◽  
Steam Turbine Blades ◽  
Positive Effect

Abstract Ni-based brazing coatings with tungsten or chromium carbides are used for wear and corrosion protection in various applications. Steam turbine blades especially present a highly stressed application in which in particular the resistance to erosion and corrosion is essential. Therefore, novel tape architectures of brazed coatings have been developed and investigated within this study. In contrast to the use of powders, the application by means of tapes offers a high potential with regard to later use in industry due to the reproducible handling and automation. In this work, different coating systems were successfully deposited by means of vacuum brazing on X12CrNiMo-12 steel substrate. In order to achieve a sufficient fracture toughness of the coatings, pure nickel powder was added to the tapes. The influence of this additive on the mechanical properties was analyzed by means of three-point bending tests. A positive effect has been observed when adding a volume fraction of φ(Ni) = 25% of nickel, increasing the flexural strength up to σf = 580 MPa. Furthermore, the surface hardness of the coating has been analyzed depending on coating architecture and post-deposition treatment by grinding.

Investigation of Steam Turbine Blades Damage and Reliability in a Power Plant

2019 ◽  
Vol 799 ◽  
pp. 89-94
Author(s):  
Artjom Molodtsov ◽  
Andrei Dedov ◽  
Ivan Klevtsov ◽  
Lembit Kommel ◽  
Toomas Lausmaa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Steam Turbine ◽  
Experimental Testing ◽  
Turbine Blades ◽  
Microstructural Analysis ◽  
Technical Requirements ◽  
Study Results ◽  
Electron Microscopes

This work presents an experimental case study of 200 MW low-pressure steam turbine rotor blades damage after 310 thousand hours of operation and 404 start-ups on the power plant. Damaged blade material was analysed by experimental testing of mechanical properties as well as crack initiation and microstructure in the damaged area by using optical and scanning electron microscopes, and investigation of chemical composition by the SEM-EDS method. Results of the investigation show that the material was die forged martensitic steel 20Cr13. The mechanical properties of the blade steel were in accordance with standard technical requirements for new material. The cross-sections of damaged and undamaged blades were investigated and compared. It was found that thickness of damaged blades was significantly less than undamaged ones. SEM-EDS analysis has shown the presence of brass fragment on the surface of one damaged blade. The microstructural analysis has shown that one of the cracks was initiated due to impact of brass fragment. Based on the given case study results it is concluded that the reason of the blade damage was a combination of at least two factors: accelerated high cycle fatigue due to increased stresses caused by excessive vibration of damaged blades with lower thickness and impact of brass fragment against blades.

Determination of crystallinity of Chinese handmade papers by means of X-ray diffraction

2020 ◽  
Vol 41 (2) ◽  
pp. 69-86
Author(s):  
Peng Liu ◽  
Hongbin Zhang ◽  
Sinong Wang ◽  
Hui Yu ◽  
Bingjie Lu ◽  
...  
Keyword(s):  
Negative Influence ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Eulaliopsis Binata ◽  
Different Types ◽  
Powder Samples ◽  
Xrd Patterns ◽  
Xrd Method

AbstractThe crystallinity indices (CrI) of Chinese handmade papers were investigated using the X-ray diffraction (XRD) method. Four Chinese handmade papers, Yingchun, Zhuma, Yuanshu and Longxucao papers were used as model substrates of mulberry bark, ramie, bamboo and Eulaliopsis binata papers, respectively. Two forms of the paper samples, paper sheets and their comminuted powders, were used in this study. The results showed that their XRD patterns belong to the cellulose-I type and Iβ dominates the cellulose microstructure of these paper samples. Moreover, it was found that the microstructures and CrIs of cellulose of these papers were changed by the grinding treatment. This work suggested that the sheet form of the handmade papers is suitable to determine CrI by XRD, despite the contribution of non-cellulosic components in the papers. The order of CrIs for these paper sheet samples was Yingchun, Zhuma, Longxucao and Yuanshu papers. Besides CrIs, differences in cross-sectional areas of the crystalline zone of cellulose can be used for comparing different types of handmade papers. It was also found that the CrIs and crystallite size of paper cellulose varied between the sheet samples and the powder samples, illustrating that the pulverisation has a negative influence on the microstructure of the handmade papers.

Diagnostics and monitoring of the operating condition of steam-turbine blades

2007 ◽  
Vol 41 (5) ◽  
pp. 295-301
Author(s):  
A. I. Danilin ◽  
S. I. Adamov ◽  
A. Zh. Chernyavskii ◽  
M. I. Serpokrylov
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Operating Condition ◽  
Steam Turbine Blades

Studies on Determination of Natural Frequencies of Industrial Turbine Blades

1995 ◽  
Author(s):  
Mahesh M. Bhat ◽  
V. Ramamurti ◽  
C. Sujatha
Keyword(s):  
Steam Turbine ◽  
Dynamic Behavior ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Complex Structure ◽  
Turbine Blades ◽  
Blade Root ◽  
Steam Turbine Blade ◽  
Manufacturing Tolerances

Abstract Steam turbine blade is a very complex structure. It has geometric complexities like variation of twist, taper, width and thickness along its length. Most of the time these variations are not uniform. Apart from these geometric complexities, the blades are coupled by means of lacing wire, lacing rod or shroud. Blades are attached to a flexible disc which contributes to the dynamic behavior of the blade. Root fixity also plays an important role in this behavior. There is a considerable variation in the frequencies of blades of newly assembled turbine and frequencies after some hours of running. Again because of manufacturing tolerances there can be some variation in the blade to blade frequencies. Determination of natural frequencies of the blade is therefore a very critical job. Problems associated with typical industrial turbine bladed discs of a 235 MW steam turbine are highlighted in this paper.

Water-droplet erosion behavior of high-velocity oxygen-fuel-sprayed coatings for steam turbine blades

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Dingjun Li ◽  
Peng Jiang ◽  
Fan Sun ◽  
Xiaohu Yuan ◽  
Jianpu Zhang ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Water Droplet ◽  
Erosion Resistance ◽  
Turbine Blades ◽  
Impingement Angle ◽  
Erosion Behavior ◽  
Water Droplet Erosion ◽  
Steam Turbine Blades ◽  
Oxygen Fuel ◽  
Sprayed Coatings

Abstract The water-droplet erosion of low-pressure steam turbine blades under wet steam environments can alter the vibration characteristics of the blade, and lead to its premature failure. Using high-velocity oxygen-fuel (HVOF) sprayed water-droplet erosion resistant coating is beneficial in preventing the erosion failure, while the erosion behavior of such coatings is still not revealed so far. Here, we examined the water-droplet erosion resistance of Cr3C2–25NiCr and WC–10Co–4Cr HVOF sprayed coatings using a pulsed water jet device with different impingement angles. Combined with microscopic characterization, indentation, and adhesion tests, we found that: (1) both of the coatings exhibited a similar three-stage erosion behavior, from the formation of discrete erosion surface cavities and continuous grooves to the broadening and deepening of the groove, (2) the erosion rate accelerates with the increasing impingement angle of the water jet; besides, the impingement angle had a nonlinear effect on the cumulative mass loss, and 30° sample exhibited the smallest mass loss per unit area (3) an improvement in the interfacial adhesion strength, fracture toughness, and hardness of the coating enhanced the water-droplet erosion resistance. These results provide guidance pertaining to the engineering application of water erosion protective coatings on steam turbine blades.

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