Abstract:
The hardness and microstructures of hypereutectoid rail welded joints after quenching and normalizing were studied. Impact tests were carried out on different rail joint zones using an impact wear tester and the impact wear and damage characteristics of each zone were analyzed. The results showed that rail joints could be divided into base material zone, weld joint zone and heat affected zone. The microstructure of base material zone was lamellar pearlite. The microstructure of the weld joint zone was composed of pearlite and proeutectoid ferrite, while the content of ferrite in normalized joint was larger than that in quenched joint; the microstructure of heat affected zone after quenching was granular pearlite, while there were a few lamellar pearlites in heat affected zone after normalizing. The rank of different zones depending on the hardness from the highest to the lowest was: base material > weld joint after quenching > weld joint after normalizing > heat affected zone after normalizing > heat affected zone quenching. The lower the hardness, the greater the impact depth and wear volume. The impact damage of the base material was slight, and the surface was slightly peeled. The weld joint was damaged severely with obvious cracks, and the damage of normalized weld joint was severer than that of quenched weld joint. The damage of the heat affected zone was the severest and the damage of normalized heat affected zone was slightly less severe than that of quenched heat affected zone.