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Microstructure and hardness of bainitic weld deposits on rails
Havlík, Petr ; Stránský, Karel (referee) ; Foret, Rudolf (advisor)
Surfacing worn crane railways as renovation technology can make several possible ways, so as manual welding whit coated electrode, with filled electrode or automatic submerged arc. The resulting mechanical properties will depend on the additional materials, which was used to create surfacing. This thesis deals whit evaluation of integrity and microstructure single - layer to three - layer surfacing with filled electrode on the rail with predominantly pearlitic structure. Were evaluated areas with the greatest heat dissipation during cooling, due to the possible occurrence of side structures. The study employed the interaction light microscopy, the scanning electron microscopy equipped by energy dispersive chemical microanalysis, the macro and micro hardness measurement by Vickers.
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Microstructure and hardness of bainitic weld deposits on rails
Havlík, Petr ; Stránský, Karel (referee) ; Foret, Rudolf (advisor)
Surfacing worn crane railways as renovation technology can make several possible ways, so as manual welding whit coated electrode, with filled electrode or automatic submerged arc. The resulting mechanical properties will depend on the additional materials, which was used to create surfacing. This thesis deals whit evaluation of integrity and microstructure single - layer to three - layer surfacing with filled electrode on the rail with predominantly pearlitic structure. Were evaluated areas with the greatest heat dissipation during cooling, due to the possible occurrence of side structures. The study employed the interaction light microscopy, the scanning electron microscopy equipped by energy dispersive chemical microanalysis, the macro and micro hardness measurement by Vickers.
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The fracture behaviour of welded joints pearlitic and bainitic rail steel
Hadraba, Hynek ; Dlouhý, Ivo ; Holzmann, Miloslav ; Zbořil, J.
The contribution is focused on analysis of welded joint made from pearlitic rail steel of type UIC 900A and newly developed cast bainitic Lo8CrNiMo steel. The lowest dynamic fracture toughness and consequently the higher risk of brittle fracture possessed the pearlitic steel and its heat affected zone (HAZ). At application temperature range the fracture toughness of this steel was on lower shelf of ductile to brittle transition, the tempering in HAZ didn't affect the toughness substantially. The dynamic fracture toughness of cast bainitic steel in joint was two times highest comparing to pearlitic one and, in addition HAZ toughness increase was found. The weld joint itself was characterised by high scatter of toughness data, nevertheless, all the values were above the scatter band characterising the more brittle pearlitic steel.
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