Features of microstructural inhomogeneity of steel 20 boiler pipes in delivery state

Anna V. Pomazova, Aleksandr A. Artamontsev, Aleksandr S. Zavorin

Результат исследований: Материалы для журналаСтатья

Аннотация

Relevance of the research is caused by the need to minimize the corrosion losses of metal of tubular heating surfaces at their operation. This largely affects the urgency of the problem of ensuring the reliable operation of boiler units at thermal power plants and industrial power facilities. The increase in reliability and safety of operation of heat-mechanical power equipment, while improving the safety of life and reducing the risk of potential harm to operating personnel and the environment, is directly related to energy-efficient use of resources. The important aspect of the relevance of the work lies in the fact that the object of the study is carbon steel pipe (steel grade 20), which belongs to the most widely used in the Russian power engineering for manufacturing boilers heating surfaces. The main aim of the study is to analyze the microrelief of the outer and inner surface of new pipe size 60×6,0 mm, made of steel 20; to study structural heterogeneity in wall thickness and size of the microstructure parameters for predictive conclusions on the reliability and the prevailing mechanisms of damage that will be developed at operation; to investigate possible additional measures improving the operational properties and service life of pipes of heating surfaces. The methods used in the study: metallographic methods of investigating the structural components of steel, micro-hardness measurement methods. The results. Different types of defects (scab unrolled, intergranular cracks, defects in the form of grooves with rounded bottoms), which are evenly distributed over the surface of the pipe, were found on the surfaces in delivery state. The defects depth reaches a half of the acceptance level for the exploited pipes. Structural inhomogeneity and difference in dimensional parameters of microstructure are detected over the thickness of the pipe wall. The presence of these defects and inhomogeneity of the pipe material lead to significant changes in failure development rate and reduce the life of boiler tubes. The authors have proposed the proprietary methods to improve surface properties and reduce structural heterogeneity of the pipes. The methods (steam-pipe processing mode, double normalization mode at 920°C) are available for implementing at thermal generation companies and reduce effectively the corrosion rate.

Язык оригиналаАнглийский
Страницы (с-по)68-75
Число страниц8
ЖурналBulletin of the Tomsk Polytechnic University, Geo Assets Engineering
Том327
Номер выпуска11
СостояниеОпубликовано - 2016

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology
  • Waste Management and Disposal
  • Economic Geology
  • Management, Monitoring, Policy and Law

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