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Copyright of Proceedings on Quality is the property of University of Zenica, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to examine the state of critical components of the boiler of Unit 5 of Kakanj Thermal Prema wer Plant, headers were tested in order to undertake appropriate technological measures and activities on the basis of insight into the current state of affairs, and to make recommendations for further exploitation. From first commissioning in 1969 to 30 April 2019 the Unit 5 boiler had 271.403 operating hours in operation and was designed for 100.000 hours. During the exploitation so far, several modifications and revitalizations have been carried out on the block, although some components from the installation period are still in operation (superheater headers Pr 5 and Pr 6). The testing program was made on the basis of analysis and evaluation of the results from previous tests and records of performed repairs on the tested components (repair of individual cracks on welded joints, created during exploitation in the previous period). The paper presents the most important data on past exploitation, the results of the NDT tests, as well as the hardness and structure tests on the replicas. Material condition assessments of critical components of Pr 5 and Pr 6 superheaters, unit 5 boiler, and recommendations for further exploitation were made based on NDT tests, as well as hardness and structure tests, in accordance with prescribed, norms and applicable standards, and structural degradation assessment and the hardness drop from the commissioning of the block to the tests carried out in the course of this work on the same or similar components. [ABSTRACT FROM AUTHOR]

This paper describes the process of degradation of the structure of the inlet header of the intermediate reheater (MPr) 2 input header at the boiler of Unit 7 of the Thermal Power Plant Kakanj, determined on the basis of tests of replicas and hardness at characteristic places of the header. Headers, with minor delays, have been in continuous operation since 1988. Hardness was tested at replica pickup sites, on the basis of which the correlation between structure degradation and hardness drop resulting from exploitation during the long-term high-temperature operation was estimated. The change in hardness is certainly one of the most reliable indicators of the structure degradation degree, which is directly related to the service life of the installed components. The subject of the test was the inlet header of the intermediate heater made of low alloy steel 15Mo3, consisting of ferrite-pearlite microstructure, and having calculated values for the allowed hardness in the range from 133 to 176 HB. The structure degradation assessment was performed according to VGB-S-517 by comparing the microstructure of the replicates with the corresponding standards, and the hardness was tested according to ASTM A 956/1996-method A. The examination has shown that in the exploitation life achieved so far, there has been a partial or complete degradation of the structure, which is reflected in the initial and delayed coagulation of the perlite lamellae (Grades 2a and 3a). The hardness at the test sites is at or below the lower than the prescribed 133HB. The tests confirmed that there is a good correlation between the degree of degradation of the structure and the hardness, which can be used in assessing the condition and planning the extent of testing on critical components. [ABSTRACT FROM AUTHOR]

Steel S690 QL is a high-strength quenched and tempered, fine-grained structural steel with a minimum yield strength of ReH of 690 MPa and with guaranteed toughness (Charpy) for rolled plates with a thickness of 3 to 50 mm. This paper presents the examination and analysis of the microstructure and grain size results after quenching and tempering. Also, the aim of the examination is to consider the segments of the technological process and its influence on the physical and metallurgical characteristics, primarily on the microstructure and grain size, which affect the tensile characteristics and toughness at low temperatures. [ABSTRACT FROM AUTHOR]

In conducted research was made a characterisation of microstructure and powder NiCrAlY, before and after applying on the base material. Coating was carried out by using HVOF Diamond Jet procedure, which uses the kinetic energy of the metal particles produced by on explosion of combustible gases. Characterisation was based on chemical analysis of metals powder particles, their size and structural composition and testing the composition, and structure of the applied coating on iron base alloy A286 with intermetallic strengthening. We used the classical testing methods of composition of metal powder and coating and optical and scanning electron microscopy in determining the phase composition. By testing with scanning electron microscopy, it was found that at the joint is present aluminium oxide with the presence of yttrium oxide, which play a significant role in the prevention of high-temperature oxidation of the base material. At the joint areal so analyzed and the concentration changes in the content of alloying elements. In addition to determining the phase composition of applied metal coating was used and x-ray structure analysis concentration changes in the content of alloying elements. [ABSTRACT FROM AUTHOR]

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)