Improvement of strength and wear resistance of stir cast SiCp/Al brake disc through friction stir processing

This study presents a hybrid manufacturing approach combining stir casting (SC) with friction stir processing (FSP) to produce high-performance SiCp/Al brake discs for high-speed commuter trains. This work is the first to apply FSP to full-size brake disc components and evaluate their tribological performance under simulated service conditions. The 20 vol% SiC-reinforced A356 alloy, initially fabricated by vacuum-assisted stir casting, exhibited typical casting defects such as porosity and particle agglomeration. These were effectively eliminated by surface FSP, which resulted in homogeneous SiC dispersion, refined microstructure, and improved interfacial bonding. Compared to SC discs, FSP discs demonstrate a significant increase in yield strength (196.8 MPa), ultimate tensile strength (219.6 MPa), and elongation (4.76 %), along with a 33 % reduction in wear loss. Moreover, the average friction coefficient of the FSP disc remains more stable across a range of braking speeds and pressures. These findings validate the feasibility of the proposed SC + FSP process as a scalable, lightweight, and durable solution for next-generation rail braking systems.