การพัฒนาโครงสร้างจุลภาคและสมบัติเชิงกลของเหล็กหล่อแท่งห้ามล้อรถไฟที่มีประสิทธิภาพ

Abstract

This reseach was to investigated and developed microstructures and mechanical properties of high phosphorous cast iron brake shoes. The investigations.found that the state railway of Thailand had been used LV4 and DR2 brake shoes of 150,000 pieces/year (485 Bahts/piece). These brake shoes were produced by locally sources. However, the cast iron brake shoes have not been researched for a long time. The quality and performance of these brake shoes did not meet the need of current and future applications in which double-track railway will be develped. Therefore, this research investigated effects of the significant foctor of the chemical composition on the microstructures (types, shapes and amounts of structures), hardness and ear of brake shoes. The results found that the microstrucutres of high phosphorus cast iron obtained the Ferrite, pearlite, phosphorus eutectic (steadite), and graphite phases. High carbon and Phosphorus resulted in the formation of the steadite phase leading to obtaind the hardness wwlue of over 240 HB. Adding an inoculant element with a proper amount contributed to form graphite phases of about 10-15%, which the hardness of the cast irons then decreased to the ange of 200-240 HB. In addition, the wear resistance of the cast iron increased with incrasing adness. The amount of porosities increased with decrasing a wear resistance. Therefore, high phosphorus cast iron should contain the cabon element of 3% and add The phosphorus element of 2%. Inoculant element should be also added for forming the Sachite phase with a proper shape and amount. Finally, the hardness of brake shoes in the requirment range were obtained.