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Projects / Programmes source: ARIS

Evolution of microstructure and properties of welding joints in thermal pover works operating at high temperature

Research activity

Code Science Field Subfield
2.04.00  Engineering sciences and technologies  Materials science and technology   

Code Science Field
T150  Technological sciences  Material technology 
T450  Technological sciences  Metal technology, metallurgy, metal products 
Keywords
alloyed steels, welding joints, microstructure, creep resistance, komponents for thermal power work
Evaluation (rules)
source: COBISS
Researchers (12)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  08236  Boris Arzenšek  Materials science and technology  Researcher  2004 - 2007  225 
2.  00741  Bojan Breskvar  Materials science and technology  Researcher  2004  160 
3.  17161  Roman Celin  Materials science and technology  Researcher  2004 - 2007  285 
4.  08797  MSc Tatjana Drglin  Cardiovascular system  Researcher  2004 - 2005  33 
5.  04982  Dimitrij Kmetič  Materials science and technology  Researcher  2004 - 2007  421 
6.  23593  PhD Gorazd Kosec  Materials science and technology  Junior researcher  2004 - 2007  229 
7.  04254  PhD Janez Šetina  Electronic components and technologies  Researcher  2004 - 2007  251 
8.  13026  PhD Roman Šturm  Manufacturing technologies and systems  Researcher  2004 - 2005  329 
9.  08195  PhD Borivoj Šuštaršič  Materials science and technology  Researcher  2004 - 2007  412 
10.  05438  PhD Matjaž Torkar  Materials science and technology  Researcher  2004 - 2007  469 
11.  17185  Gvido Velikajne    Technical associate  2004 - 2007  192 
12.  09788  PhD Jelena Vojvodič Tuma  Civil engineering  Head  2004 - 2007  629 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0206  Institute of Metals and Technology  Ljubljana  5051622000  5,981 
Abstract
The most important part of termal power works, where steam is overheated are connected in a closed system with welding joints. The temperature in these parts is sufficient to induce changes of microstructure and a gradual decrease of steel creep resistance. Due to the difference in local heating temperature and cooling rate after welding, joints have a very heterogeneus microstructure. During the operation also in these joints changes occur, which affect the microstructure and the creep resistance. Earlier investigations have shown f.i. that the creep resistance of a steel was decreased by appr. 4 times, when the internal recrystallisation changed the microstructure from tempered martensite to an homogeneus distribution of carbide particles in ferrite grains, although no significant change in the size of carbide particles was established. It is clear, thus, that the creep resistance depends strongly also on the morphology of the microstructure rsp. of the carbide particles distribution. In welded joints part of the microstructure is produced at solidification and part with transformation of austenite heated at different local temperature and cooled at different rate. F.i. the austenite grain size is by appr. one order of magnitude greater in the contact layer solid-liquid steel than in the area, where the temperature was of 1000 oC or lower. The difference in grain size induces a difference in hardenability, which is reflected in a variety of microstructures, carbide particles distribution and hardness significantly different than those in the welded steel. For this reason, it is assumed that the morphology and kinetics of microstructure changes in welding joints differ of those in the welded steel. These changes and their effect on creep resistance will be investigated in this project.
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