MAZANCOVÁ Eva VSB - Technical University of Ostrava

The work deals with fractal response study of root of the TH29 profile from carbon steel micro-alloyed with vanadium (0.12 %), niobium (0.04%) and nitrogen (0.012 %) designated for mine supports. The profile was evaluated both after hot rolling and after subsequent straightening that showed different impact energy values, even when the feature of fracture surfaces did not differ significantly. It was reason for fractal response study which proofed important differences between both treated materials. For solution Mandelbrot-Richardson concept was used. Surface roughness parameters (Rs) and fractal dimensions (D) for root demonstrated higher values after hot rolling. In this case microstructure evaluation also showed lower acicular ferrite portion supporting balance between strengthening, toughness and elimination of harmful segregation banding.