Modelling and experimental study of laser-assisted milling of fibre reinforced SiC/Ti-6Al-4V metal matrix composite

Abstract

Metal matrix composites (MMCs) offer unique advantageous mechanical properties by strengthening a ductile metal matrix with a ceramic reinforcement (e.g., Ti6Al-4 V/SiCf). However, their heterogeneous composition poses machining challenges including fibre pullout, matrix cracking, and increased tool wear. Whilst pre-heating via laser-assisted machining (LAM) shows promise for improving machinability, traditional LAM implementations with a fixed laser spot size and straight laser path prevent uniform heating. By introducing spatially and temporally controlled LAM that generates homogeneous heating by varying the laser scanning velocity, a technique called fully inverse LAM can be applied for MMCs. This involves calculating separate temperature fields for the matrix and reinforcement to minimise thermal mismatch stresses. The fully inverse LAM decreases subsurface cracks and delamination resulting from conventional milling, whilst localised matrix softening reduces cutting forces by over 62 %. Flank tool wear is also diminished, increasing tool life by 120 %. Material analysis reveals reduced machined surface damage, lower surface roughness, and less formation of intermetallic compounds (Ti2C) compared to traditional LAM.