Automatic Welding, 2016, №03



2016 №03 (04)

DOI of Article 10.15407/as2016.03.05

2016 №03 (06)

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Avtomaticheskaya Svarka (Automatic Welding), #3, 2016, pp. 35-43
 

Improvement of the technology of welding high-temperature diaphragms in steam turbine flow section

A.K. Tsaryuk¹, V.Yu. Skulsky¹, M.A. Nimko¹, A.N. Gubsky², A.V. Vavilov² And A.G. Kantor²

¹E.O. Paton Electric Welding Institute, NASU. 11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: office@paton.kiev.ua
²Company «Turboatom». 199 Moskovsky Ave., 61037, Kharkov, Ukraine. E-mail: office@turboatom.com.ua
 
Abstract
Special features and causes for operational damage in welded components of high-temperature diaphragms are considered. Comparative testing was performed of welding-technological properties of some commercially available coated electrode grades for welding heat-resistant steels of Cr–Mo and Cr–Mo–V compositions. Implant procedure and welding of Tekken technological samples were used to assess the delayed fracture susceptibility of 15Kh12VNMF + 15Kh1M1FL steel welded joints at application of selected electrodes. It is established that to ensure a high cold cracking resistance of these steel welded joints, it is necessary to apply preheating at 200–250 °C. Proceeding from the data of measurement of metal hardness in welds and HAZ of welded joints and weld metal impact toughness, an optimum mode of heat treatment of 15Kh12VNMF + 15Kh1M1FL steel welded joints was determined. It is shown that a softening zone of lower hardness forms in the HAZ metal structure of 15Kh12VNMF steel, in which the samples fail at testing for static tension at working temperature of 570 °C. 8 Ref., 4 Tables, 10 Figures.
 
Keywords: arc welding, heat-resistant steels, dissimilar steel welded joints, cold cracks, heat treatment
 
Received:                22.12.15
Published:               28.04.16
 
 
References
 

1. Shlyakhin, P.N. (1974) Steam and gas turbines. Moscow: Energiya.
2. OST 108.021.04–78: Stationary steam turbines. Welded diaphragms, guide apparatuses. General specifications. 01.01.79.
3. Mellerovich, G.M., Pelipenko, E.N., Pokrassa, M.I. et al. (1969) Study of stress state of steam turbine casings and diaphragms. Problemy Prochnosti, 4, 19–22.
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7. RTM 108.020.35–81: Stationary steam turbines. Welding and heat treatment of diaphragms and guide apparatuses. Fundamentals.
8. Kozlov, R.A. (1986) Welding of heat-resistant steels. Leningrad: Mashinostroenie.