PSI - Issue 13

Ivica Čamagić et al. / Procedia Structural Integrity 13 (2018) 2249 – 2254 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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5. Conclusions

Measuriong of welded joint hardness determined the influence of exploitation time on a decrease in its values, along with the effect of exploitation time on the weakening of the PM and HAZ. Measured hardness values for the butt-welded joint ranged from 180 to 189 HV in the WM. In the HAZ, obtained values were slightly lower compared to the WM. There is a noticeable difference in the HAZ for the new and exploited PM. New PM had shown higher hardness values, ranging from 167 to 175 HV, whereas the hardness of the exploited PM was between 157 and 167 HV. Different hardness values were determined for both new and exploited PM, 143-156 HV for the former and 131 140 HV for the latter [1]. Never the less both parent metals shows uniform structure that consists of bright polygonal ferrite crystals and transformed areas, basic difference between new and old material is in grain size. Newly installed parent metal has a structure with grain size 5 according to ASTM scale, while exploited material has a structure with grain size 3 according to ASTM scale, as the result of higher temperature and pressure influence in longer time period, [1]. The amount of segregated carbide at a grain border, as well as within a grain, is especially significant in a PM behaviour in presence of variable load, [1, 8]. Test results and their analysis have justified the choice of welding technology for the purpose of replacing the part of the reactor mantle.

6. Acknowledgements

Parts of this research were supported by the Ministry of Sciences and Technology of Republic of Serbia through Mathematical Institute SANU Belgrade Grant OI 174001 Dynamics of hybrid systems with complex structures. Mechanics of materials and Faculty of Technical Sciences University of Pristina residing in Kosovska Mitrovica.

References

[1] Ivica Čamagić, Investigation of the effects of exploitation condi¬tions on the structural life and integrity assessment of pr essure vessels for high temperatures (in Serbian), doctoral thesis, Fakultet tehničkih nauka, Kosovska Mitrovica, 2013. [2] SRPS EN ISO 9692-1:2012, Welding and allied processes - Recommendations for joint preparation - Part 1: Manual metal-arc welding, gas shielded metal-arc welding, gas welding, TIG welding and beam welding of steels (ISO 9692-1:2003), 2012. [3] SRPS EN ISO 9692-2:2008, Welding and allied processes - Joint preparation - Part 2: Submerged arc welding of steels (ISO 9692-2:1998), 2008. [4] EN 1043, Destructive tests on welds in metallic materials-Hardness test Part 2, Micro hardness testing on welded joints, 1996. [5] "Classification of Microstructures in Low C, Low Alloye Steel Weld Metal and Terminology", MIZ, IX-1282-83. [6] METALS HANDBOOK, Metalography, Vol. 6, ASM International, pp. 1124, 1998. [7] "Weld Metal Microstructures", A State-of-the Art review. [8] Ivica Čamagić, Nemanja Vasić, Srdjan Jović, Zijah Burzić, Aleksandar Sedmak, Influence of temperature and exploitation time on tensile properties and microstructure of specific welded joint zones, 30th International Congress of Serbian Society of Mechanics, Arandjelovac, Serbia, June 15-17, 2015.