Proučavanje faznih transformacija u zoni uticaja toplote aluminotermijski zavarenih čelika za šine eksperimentalnim metodama i simulacijom

Abstract

Rail transportation has been an emerging and promising transportation method for economic development in Thailand and several countries. Thermite welding is one of the major welding and joining processes used to weld rail steel both during construction and maintenance. Unlike most welding processes in which heat is generated by electrical energy, thermite welding use heat generated during the chemical reactions between iron oxide and aluminum or other metallic compounds to create the weld. The amount of heat generated is thus depended on the composition and ratios of iron oxide, aluminum, as well as other metallic compounds mixed in the thermite powder. In addition, the size, shape, and material used for thermite mold could also play an important role in the heat transfer process during thermite welding of rail steel. In this research, SYSWELD software developed by ESI Group is used to perform thermal-mechanical-metallurgical welding simulation during thermite welding of rail steel. The current article presents that research methodology used to formulate the prediction of microstructure developed in the heat-affected zone regions of thermite welding of railway steel. It is noted that this work attempts to evaluate how preheat, heat generation during chemical reaction, and possible post-weld heat treatment could be performed to controlled the microstructure of pearlitic rail steel using SYSWELD software. The results of this on-going research will be used as the baseline for future development of structural integrity program for improving joining of rail steel such as the design and selection of welding processes and materials involved for rail construction, especially when appropriate grades and welding procedures of rail steels must be chosen and developed to withstand the actual loading conditions.