Savremene tehnologije nanošenja prevlaka i njihova potencijalna primena na termoenergetskim postrojenjima

Istraživanja u okviru ove doktorske disertacije posvećena su izučavanju savremenih tehnologija nanošenja zaštitnih prevlaka nove generacije koje se mogu koristiti u termoenergetskim postrojenjima. Kao najčešći problemi izdvajaju se erozija materijala komponenti termoenergetskog postrojenja pri ekstremnim uslovima rada (velike brzine čestica erodenta i mali uglovi nastrujavanja) i ubrzana oksidacija usled dejstva visokih temperatura...Research within this doctoral dissertation is devoted to the study of modern technologies for the application of a new generation erosion resistant coatings that can be used in thermal power plants (TPP). The most common problems during service of TPP components are related to the severe erosion of the materials exposed to the extreme conditions during operation (high-velocity erodent particles impact and the low impact angle of the erodent particles) and also accelerated oxidation due to the high operating temperature..

Determination of the Actual Stress-Strain Diagram for Undermatching Welded Joint Using DIC and FEM

This paper presents new methodology for determining the actual stress-strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress-strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress-strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress-strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry

Determination of the Actual Stress-Strain Diagram for Undermatching Welded Joint Using DIC and FEM

This paper presents new methodology for determining the actual stress-strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress-strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress-strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress-strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry

Application and design of an economizer for waste heat recoveryin a co-generation plant

Energy increase cost has required its more effective use. However, many industrial heating processes generate waste energy. Use of waste-heat recovery systems decreases energy consumption. This paper presents case study of waste heat recovering of the exhaust flue gas in a 1415 kWe co-generation plant. This waste heat can be recovered by installing an economizer to heat the condensed and fresh water in thermal degasification unit and reduce steam use for maintaining the temperature of 105 degrees C for oxygen,removal. Design methodology of economizer is presented

Oxidation behavior during prolonged service of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V heat resistance steels

During service of thermal power plant (TPP) units, different components are exposed to high temperature due to technological cycle of TPP unit. Service lifetimes of these components, especially boiler heating surfaces, may be limited due to creep, fatigue or oxidation, but materials designed for use at high temperatures have been developed primarily for their creep properties and microstructural stability during long term exposures at elevated temperatures. Having in mind that oxidation in steam environment on the inner surface of boiler tubes and in flue gass on the outer surface of boler tubes could lead to a different consequences regarding service life of tubes, either directly through metal wastage or indirectly through raising local temperatures due to the lower thermal conductivity of the oxide scale, the oxidation behaviour of a different heat resistant steels become very important characteristics. In this paper are presented some data about the oxidation behavior of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V steel after service of approximately 130.000 and 200.000h in two 620MVV TPP units. Characterization of oxide scales on the inner side on tubes made of two steels with different chromium content, after two different prolonged periods of service, were compared and also their influence on the service life of tubes and kinetics of oxide scale growth were analyzed

Oxidation behavior during prolonged service of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V heat resistance steels

During service of thermal power plant (TPP) units, different components are exposed to high temperature due to technological cycle of TPP unit. Service lifetimes of these components, especially boiler heating surfaces, may be limited due to creep, fatigue or oxidation, but materials designed for use at high temperatures have been developed primarily for their creep properties and microstructural stability during long term exposures at elevated temperatures. Having in mind that oxidation in steam environment on the inner surface of boiler tubes and in flue gass on the outer surface of boler tubes could lead to a different consequences regarding service life of tubes, either directly through metal wastage or indirectly through raising local temperatures due to the lower thermal conductivity of the oxide scale, the oxidation behaviour of a different heat resistant steels become very important characteristics. In this paper are presented some data about the oxidation behavior of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V steel after service of approximately 130.000 and 200.000h in two 620MVV TPP units. Characterization of oxide scales on the inner side on tubes made of two steels with different chromium content, after two different prolonged periods of service, were compared and also their influence on the service life of tubes and kinetics of oxide scale growth were analyzed

Oxidation behavior during prolonged service of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V heat resistance steels

During service of thermal power plant (TPP) units, different components are exposed to high temperature due to technological cycle of TPP unit. Service lifetimes of these components, especially boiler heating surfaces, may be limited due to creep, fatigue or oxidation, but materials designed for use at high temperatures have been developed primarily for their creep properties and microstructural stability during long term exposures at elevated temperatures. Having in mind that oxidation in steam environment on the inner surface of boiler tubes and in flue gass on the outer surface of boler tubes could lead to a different consequences regarding service life of tubes, either directly through metal wastage or indirectly through raising local temperatures due to the lower thermal conductivity of the oxide scale, the oxidation behaviour of a different heat resistant steels become very important characteristics. In this paper are presented some data about the oxidation behavior of boiler tubes made of 2.25Cr1Mo and 12Cr1Mo0.3V steel after service of approximately 130.000 and 200.000h in two 620MVV TPP units. Characterization of oxide scales on the inner side on tubes made of two steels with different chromium content, after two different prolonged periods of service, were compared and also their influence on the service life of tubes and kinetics of oxide scale growth were analyzed

Influence of plasma transferred arc welding parameters on the obtained microstructure of 316L coating

The paper describes the surfacing technology for coating of high-alloyed austenitic stainless steel 316L on the steel S235JR base material. Coatings were applied by plasma transferred arc welding process. The 5 samples were made using different welding currents while other welding param-eters were constant. Metallographic analysis of the obtained samples is used to establish a correlation between the micro-structural constituents and the applied welding current in the surfacing process. According to this it was possible to determine the optimal parameters of coating surfacing. The filler material was in the form of powder, while its charac-terization was performed by scanning electron microscopy, and the characterization of the obtained coatings by optical microscopy. © 2023 Society for Structural Integrity and Life (DIVK). All rights reserved.Ovaj rad opisuje tehnologiju navarivanja prevlake od visokolegiranog austenitnog nerđajućeg čelika 316L na osnovni materijal od čelika S235JR. Prevlaka je nanesena tehnikom navarivanja plazmom. Izrađeno je 5 epruveta sa različitim vrednostima jačine struje, dok su ostali parametri navarivanja bili konstantni. Metalografska analiza dobijenih epruveta je iskorišćena za uspostavljanje korelacije između mikrostrukture i jačine struje tokom procesa navarivanja. Na osnovu toga je bilo moguće odrediti optimalne parametre za navarivanje. Korišćen je dodati materijal u obliku praha i njegova karakterizacija je izvršena uz pomoć skenirajućeg elektronskog mikroskopa, dok je karakterizacija samog navarenog sloja urađena primenom optičkog mikroskopa.This paper was presented at the Second International Symposium on Risk Analysis and Safety of Complex Structures and Components (IRAS 2023), 2-4 April 2023, Belgrade, Serbi

Erosion wear of HCCI alloys

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia