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1 International Journal of Applied Mechanics and Engineering

1 2010

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Flash butt weldability of austenitic high strength steels

Schmidova E., Svanda P., Konecny M.

International Journal of Applied Mechanics and Engineering

2010

Vol. 15, no 2

477-482

This paper deals with specific changes in the structure of crossings made of Hadfield's steel, caused by heat and mechanical stress during the welding process, and of rails made of carbon steel. Experiments were undertaken to analyze the sources of damage to the weld joint, established by a post-weld capillary test after machining the weld joints. The analysis demonstrated the presence of welding defects consisting of a phosphide phase and of carbides as a secondary phase. The distribution and amount of this undesirable phase was given by the technical welding parameters employed. It was established that the material is prone to hot tearing only in a very narrow zone inside the heat-affected zone where comprehensive reaustenitization takes place. Initiation of the defects is related to the presence of a phosphide eutectic. A further growth of cracks takes place along the carbide border line; this means that the main factor limiting the use of such welds is attainment of structural degradation. Reducing the thermal effect on the welded components is thus essential for further use of the investigated samples