WELDING OF S355J+N LOW ALLOY STEEL ELEMENTS IN RAILWAY CARRIAGES STRUCTURES

Various types of structures and materials play an important role in the creation modern means of transport, including various grades of steel with different mechanical properties. For the rolling stock, proper operation and meeting the operational conditions is very important. Welded structures play an important role in the construction of various means of transport. Correct welding of carriages is important both in production and when carrying out various types of repairs. Each repair a carriage depends on its advancement and condition and the time of its operation. Each inspection for a refurbished carriage is defined either by the service life or the big distance traveled by the carriage. Important factor that may lead to damage is the effect of the load transported in the carriage. Therefore, the causes of the wear of the rolling stock are investigated and measures are taken to prevent any damage. The appropriate technical condition of the carriage also ensures safety on railroads for users and owners of the rolling stock. In the case of welded structures in carriages, it is influenced by poorly materials choice, incorrectly selected production processes and wrong selection of parameters. The goal of this paper is the mechanical properties analyse of weld low alloy steel structure of carriages after MAG welding using the parameters of the process. Thick-walled steel structures are used to build carriages, which is often a serious welding problem. The main role of welding conditions is connected with filer materials, welding technology, state of stress and temperature. In this paper, the properties of low alloy steel S3555J+N structures after MAG welding are presented. Furthermore, metallographic structure, tensile strength, bending test and impact toughness welded joints were analysed regarding welding parameters. The amount of acicular ferrite in WMD oxygen after welding was tested. Gas mixtures of argon and carbon dioxide with various percentage was used for shielding gas.