ข้อมูลผลงานวิจัย

Construction of railway track is one major component of developing railway transportation. Railway track is made of high quality steels and includes several sizes depending on service loading conditions. In order to create a sound joint between railway track, it is important to control process parameters involved in welding of two pieces of railway steels together. In this research, Jominy end quench test method according to ASTM A255 was selected as investigate the hardenability and the weldability of the railway head sections of two different initial hardness. The peak annealing temperatures were selected at 850oC and 950oC in furnace with the annealing time at peak temperature of one hour. After annealing, the specimen was removed from the furnace and quenched with running water at the bottom of the specimen. To determine the changes and distribution in hardness at different cooling rates, Rockwell C hardness measurement was performed at different positions. It was found that the specimens with higher initial hardness has higher hardenability compared to specimens with lower initial hardness. By using higher annealing temperature, the overall hardness was found to be slightly smaller compared to lower annealing temperature. Also, the weldability of specimens with lower initial hardness was better than specimens with higher initial hardness as less volume fraction of martensite formed. In order to create a sound weld with both strength and ductility, it is important to control cooling rate to prevent and avoid formation of martensite structure in the railway steel joint.