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.

Development of a water droplet erosion model for large steam turbine blades

2003 ◽  
Vol 17 (1) ◽  
pp. 114-121 ◽  
Author(s):  
Byeong- Eun Lee ◽  
Kap- Jong Riu ◽  
Se- Hyun Shin ◽  
Soon- Bum Kwon
Keyword(s):  
Steam Turbine ◽  
Water Droplet ◽  
Turbine Blades ◽  
Erosion Model ◽  
Water Droplet Erosion ◽  
Steam Turbine Blades

Water droplet erosion of stainless steel steam turbine blades

2017 ◽  
Vol 4 (8) ◽  
pp. 086510 ◽  
Author(s):  
H S Kirols ◽  
D Kevorkov ◽  
A Uihlein ◽  
M Medraj
Keyword(s):  
Stainless Steel ◽  
Steam Turbine ◽  
Water Droplet ◽  
Turbine Blades ◽  
Water Droplet Erosion ◽  
Steam Turbine Blades

Advanced Water Droplet Erosion Protection for Modern Low Pressure Steam Turbine Steel Blades

2015 ◽  
Author(s):  
Joerg Schuerhoff ◽  
Andrei Ghicov ◽  
Karsten Sattler
Keyword(s):  
Steam Turbine ◽  
Water Droplet ◽  
Precipitation Hardening ◽  
Turbine Blades ◽  
Low Pressure ◽  
Steam Turbines ◽  
Treatment Facility ◽  
Material Loss ◽  
Pressure Steam ◽  
Steam Turbine Blades

Blades for low pressure steam turbines operate in flows of saturated steam containing water droplets. The water droplets can impact rotating last stage blades mainly on the leading edge suction sides with relative velocities up to several hundred meters per second. Especially on large blades the high impact energy of the droplets can lead to a material loss particularly at the inlet edges close to the blade tips. This effect is well known as “water droplet erosion”. The steam turbine manufacturer use several techniques, like welding or brazing of inlays made of erosion resistant materials to reduce the material loss. Selective, local hardening of the blade leading edges is the preferred solution for new apparatus Siemens steam turbines. A high protection effect combined with high process stability can be ensured with this Siemens hardening technique. Furthermore the heat input and therewith the geometrical change potential is relatively low. The process is flexible and can be adapted to different blade sizes and the required size of the hardened zones. Siemens collected many years of positive operational experience with this protection measure. State of the art turbine blades often have to be developed with precipitation hardening steels and/or a shroud design to fulfill the high operational requirements. A controlled hardening of the inlet edges of such steam turbine blades is difficult if not impossible with conventional methods like flame hardening. The Siemens steam turbine factory in Muelheim, Germany installed a fully automated laser treatment facility equipped with two co-operating robots and two 6 kW high power diode laser to enable the in-house hardening of such blades. Several blade designs from power generation and industrial turbines were successfully laser treated within the first year in operation. This paper describes generally the setup of the laser treatment facility and the application for low pressure steam turbine blades made of precipitation hardening steels and blades with shroud design, including the post laser heat treatments.

Increased liquid droplet erosion resistance of steam turbine blades

2007 ◽  
Vol 2 (1) ◽  
pp. 13-18
Author(s):  
F. Pratesi ◽  
M. Giannozzi ◽  
E. Giorni ◽  
I. Giovannetti ◽  
G. Zonfrillo
Keyword(s):  
Steam Turbine ◽  
Erosion Resistance ◽  
Liquid Droplet ◽  
Turbine Blades ◽  
Steam Turbine Blades
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