Obrabotka Metallov. 2017 no. 3(76)

OBRABOTKAMETALLOV № 3 (76) 2017 33 TECHNOLOGY Investigation of Welded Rail Joints after Machining at Different Post-Weld Temperature Andrey Ilinykh 1, a , Marina Galay 1, b,* , Eduard Sidorov 1, с 1 Siberian Transport University, 191 Dusi Kovalchuk st., Novosibirsk, 630049, Russian Federation a http://orcid.org/0000-0002-4234-6216 , asi@stu.ru , b http://orcid.org/0000-0002-7897-1750 , galayms@mail.ru , c http://orcid.org/0000-0001-6237-142X , sesnsk@mail.ru ARTICLE INFO Article history : Received: 15 May 2017 Revised: 17 June 2017 Accepted: 25 July 2017 Available online: 15 September 2017 Keywords : Rails Aluminothermic Welding Grinding Process Hardness Surface Roughness ABSTRACT Welded rail joints are integral part of continuous welded rail. However, its reliability during the operation is no sufficiently high. The influence of the grinding process of aluminothermite welded rail joints, performed at different values of the residual post-weld temperature of the weld, on the physical and mechanical properties and roughness of the rolling surface is investigated. The process of grinding is carried out at different values of residual post-weld temperature. The interval of post-weld temperatures in the zone of grinding of welded joints was 600…850 ° C. It is established that, different temperature regimes, when performing the technological operation of grinding aluminothermite joints, lead to the formation of non-identical mechanical properties of the metal surface of the rail head in the weld zone. Grinding at a residual post-weld temperature of the weld surface of 850 ℃ or 600 ℃ allows the highest hardness values of 33 ... 36 HRC to be achieved, while grinding at a residual temperature of 800 ℃ or 700 ℃ results in a decrease in the hardness of the weld metal to 25 ... 30 HRC. However, after grinding when the residual post-weld temperature is 800…700 ℃ hardness of the welded metal decreases from 25 to 30 HRC. Reducing the temperature of the metal surface of the railhead before grinding from 850 ℃ to 600 ℃ allows reducing the roughness of the rolling surface from 2.5 microns to 0.7 microns. The received results indicate that the highest values of hardness and surface finish can be reach when temperature of rail welded joint head metal is 600 ℃ during grinding when carrying out process of welding. It can be claimed that grinding of rails welded joints in a hot state is the perspective direction in the field of improvement of post-weld technological process of welded joints. For citation: Ilinykh A.S., Galay M.S., Sidorov E.S. Investigation of welded rail joints after machining at different post-weld temperature. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2017. no. 3 (76), pp. 28–34. doi: 10.17212/1994-6309-2017-3-28-34. (in Russian). References 1. Yamamoto R., Terashita Y., Tatsumi M., Itoh H., Umenai K. Investigation of cause and prevention measures against surface defects on thermit welds. Quarterly Report of RTRI , 2016, vol. 57, no. 2, pp. 112–117. doi: 10.2219/ rtriqr.57.2_112. 2. Costea D.M., Gảman M.N., Dumitru G. The weld aluminothermic optimization of rail track by microalloyed. Bulletin of the Transilvania University of Braşov CIBv , 2014, vol. 7 (56), special iss. 1, pp. 285–288. 3. BrânzeiM, ComanT. Structure improvement of aluminothermicwelding joints by usingmodifiers. International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering , 2012, vol. 6, no. 8, pp. 745–748. 4. Mouallif Z., Radi B., Mouallif I. The thermomechanical modeling of aluminothermic welds affected by different defects. International Journal of Engineering Research and Development , 2015, vol. 11, iss. 10, pp. 44–48. ______ * Corresponding author Galay Marina S. , Ph.D. (Engineering) Siberian Transport University, 191 Dusi Kovalchuk st., 630049, Novosibirsk, Russian Federation Е-mail: galayms@mail.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2017 no. 3(76) pp. 28–34 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2017-3-28-34 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov