Microstructure Development of a Functionalized Multilayer Coating System of 316l Austenitic Steel on Grey Cast Iron Under Braking Force in a Corrosive Environment

Brake discs made of grey cast iron with lamellar graphite (GJL) offer an excellent combination of strength and thermal conductivity, which is essential for the high demands on braking performance and durability in the automotive industry. However, the resulting dust emissions are a disadvantage that can be mitigated by applying a wear‐resistant coating on the brake disc using the Laser Metal Deposition (LMD) process. In this study, the influence of the braking force on the microstructure of the coated brake disc in a corrosive environment was investigated. The surface of grey cast iron brake discs was functionalized with 316L stainless steel, which was partially reinforced with tungsten carbide particles using the LMD process.The main objective is to improve the wear and corrosion resistance of brake discs under operating conditions. The samples were subjected to a brake shock corrosion test, which simulates real thermal and mechanical loads. Microstructural analysis was performed using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) to evaluate microstructural features such as grain size, grain orientation and phase distribution before and after the brake shock corrosion test. The study highlights the critical importance of understanding thermal effects and microstructural changes to optimize brake performance and ensure safety.The most important results include the promotion of grain growth, crystal reorientation and texture changes through thermal and mechanical alternating stress as well as the improvement of wear resistance through the incorporation of tungsten carbide particles in stainless steel.