Automatic Welding, 2021, №11



2021 №11 (05)

DOI of Article 10.37434/as2021.11.06

2021 №11 (07)

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Avtomaticheskaya Svarka (Automatic Welding), #11, 2021, pp. 35-39

Investigation of the causes for appearance of defects in welded butt joints of tram rails made by thermit welding

E. Turik¹, I.O. Ryabtsev², M. Lomozik¹, K. Krasnovskyi1¹

¹Lucasiewicz Research Network – Institute of Welding, 44-100, Gliwice, 16-18 Bl. Czeslava, Poland. Е-mail: is@is.gliwice.pl
².O. Paton Electric Welding Institute of the NAS of Ukraine. 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: office@paton.kiev.ua

The results of investigations of the causes for fatigue fracture of rail butt joints on two new tram tracks, made by thermit welding by two organizations are presented. Control analysis of the chemical composition and mechanical properties of the rail material; analysis of the chemical composition of the welds; macroscopic and microscopic investigations of the weld, HAZ and base metal; and hardness studies in these zones were performed. It was found that pore accumulation and isolated microcracks in the weld metal are the potential cause for cracking. Violations of the technological process of thermit welding of the tram tracks were determined, which lead to appearance of these defects. The detected defects are the result of the following factors, associated with failure to meet the standard requirements on thermit welding of tram tracks and of the system of ensuring the quality of welding operations, namely violation of welding technology and insuffi cient control at the respective stages of the production process. 12 Ref., 7 Fig.
Keywords: thermit welding, tram tracks, fatigue cracks, porosity, microcracks, quality assurance system


Received: 16.09.2021

References

1. PN-EN 16771:2017-01 Railway applications – Infrastructure – Aluminothermic welding of grooved rails.
2. PN-EN 14730-1:2017-06 Railway applications – Track – Aluminothermic welding of rails. Part 1: Approval of welding processes.
3. ДСТУ EN ІSO 3834-2:2019 Вимоги до якості зварювання плавленням металевих матеріалів. Частина 2. Всебічні вимоги до якості.
4. PN-EN 14811:2019-06 Railway applications. Track. Special purpose rail. Grooved rails and associated construction profiles.
5. Lawrence F.V., Chen Y-R., Cyre J.P. Improving the fatigue resistance of thermite railroad rail weldments. http://fcp. mechse.illinois.edu/files/2014/07/Lawrence-presentation.pdf
6. Thermit SRZ/SRZ L50/SRE welding process for grooved rails. https://www.elektro-thermit.de/fileadmin/et/user_upload/ PDF/Produktbrosch%C3%BCren/SRZ_SRE_DEF.pdf
7. ДСТУ EN 10204:2017 Вироби металеві. Види документів контролю.
8. PN-EN 14730-2:2006 Railway applications – Track – Aluminothermic welding of rails. Part 2: Qualification of aluminothermic welders, approval of contractors and acceptance of welds.
9. (2010) Code of Practice for the THERMIT – Quick Welding Procedure SoWoS. Elektro-Thermit GmbH & Co KG.
10. (2019) Instrukcja spawania szyn termitem Id-5. PKP Polskie Linie Kolejowe S.A.
11. Code of Practice for the THERMIT – Quick Welding Procedure SkV. Elektro-Thermit GmbH & Co KG, 2010. https://www.thermit.com.au/media-centre/technicalinformation/ PI_8.5.1-296_TA_TS-Code-of-Practice-SkVElite- Welding-Procedure.pdf.
12. Elektro-Thermit. Technology of aluminothermic welding of rails with short time of heating (SkV, SkV-L 50, SkV-L 75). https://docplayer.com/27763010-Elektro-termittehnologiya- alyuminotermitnoy-svarki-relsov-s-korotkimvremenem- podogreva-skv-skv-l-50-skv-l-75.html.

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