Reconditioning of airfoil geometry for the last stages blades of steam turbines at thermal and nuclear power plants by applying of electro-spark erosionproof coatings
Închide
Articolul precedent
Articolul urmator
519 3
Ultima descărcare din IBN:
2021-03-30 15:51
SM ISO690:2012
BELYAKOV, A., GORBACHEV, A., PARABIN, V.. Reconditioning of airfoil geometry for the last stages blades of steam turbines at thermal and nuclear power plants by applying of electro-spark erosionproof coatings. In: Materials Science and Condensed Matter Physics, Ed. 7, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, Editia 7, p. 340.
EXPORT metadate:
Google Scholar
Crossref
CERIF

DataCite
Dublin Core
Materials Science and Condensed Matter Physics
Editia 7, 2014
Conferința "Materials Science and Condensed Matter Physics"
7, Chișinău, Moldova, 16-19 septembrie 2014

Reconditioning of airfoil geometry for the last stages blades of steam turbines at thermal and nuclear power plants by applying of electro-spark erosionproof coatings


Pag. 340-340

Belyakov A., Gorbachev A., Parabin V.
 
Open joint-stock company, "All-Russian twice Order of Labor Red Banner, Thermal Engineering Research Institute"
 
 
Disponibil în IBN: 23 martie 2019


Rezumat

The process of recovery of full profile working blades (WB) of the last stages of steam turbines is as follows. On the leading edge with RL removed from the protective lining plates cobalt stellite V3K (turbine thermal power plants), and the remnants of electric-layer coating or layer on the leading edge, resulting hardened by high frequency (turbines of nuclear power plants) and prepare the damaged surface of the pen WB from its input and output edges of the mechanical removal of the metal in the eroded areas.  Then, the prepared surface of the pen 1 on the WB input edge are deposited by argon-arc welding in pulsed mode of reducing a metal cladding ductile nickel-base alloy having a high fracture toughness, with the following component composition: Ni -60 ÷ 80% , Fe - 8 ÷ 10%, the balance - other alloying elements up to 100%. Surfacing in the prepared surface area WB pen from its leading edge are to achieve recoverable portion WB size sufficient to form the profile of the pen WB oversize 4 ÷ 6 mm. The high nickel content in the coating materials provides austenitization in the weld zones of high-chromium martensitic steel, which is made WB (steel 15H11MF-Sh), which, in turn, creates the conditions for the absence of the quenching of the structure and reduces the risk of quench cracking in the heat affected zones. Such properties of the deposited material creates the conditions for filling (so-called "healing") arising microdefects and prevent the occurrence of cold cracking. Surfacing in pulsed mode reduces the amount of heat introduced into the WB, and reduces the residence time WB at elevated temperature. The use of pulsed mode allows to obtain a fine grain structure of the deposited metal by improving the conditions of crystallization and, as a consequence, the higher its durability, hardness, and resistance to erosion.  After applying the surfacing and subsequent cooling of the deposited layer were monitored for defects, carry out mechanical removal of excess metal and the resulting surface layer WB 1 is reinforced by surface plastic deformation (SPD) to a depth of 40 ÷ 100 microns (meaning hardened layer thickness). Hardening can be carried out by the SPP in various ways, such as treatment bombardment steel micro beads, blasting, ultrasonic forging etc.  After heat treatment restored sites WB form a protective reinforcement layer erosion proofed alloy by electrospark method on the surface of the pen WB from its leading edge WB surfacing over and from its trailing edge - pure metal surface to achieve recoverable portions WB sizes sufficient to generate the profile of the stylus WB oversize 4 ÷ 6 mm. Application electrospark method protective reinforcement layer is carried out by erosion-resistant alloy surface WB pen from its front edge with a single pulse energy of 3 from 9 to 42 Dg with a specific time doping 0,3 ÷ 0,5 min/sm2 and from its output edges 5 - from 0.4 to 2.0 joules with a specific time doping 0,1 ÷ 0,2 min/sm2 electrode material based on tungsten carbide or titanium carbide with cobalt or nickel binder is not more than 10% by weight or of cobalt-based with a cobalt content of at least 60 weight%, and carbon of 1.0 to 1.5% chromium with additions of iron and molybdenum in an amount up to 100%. In the process of forming a layer of electro interelectrode gap provides air under pressure for cooling the electrode, which can be heated up to rapid oxidation.