A method for manufacturing a composite part includes preparing a stack of plies made of a starting material, applying a vacuum bag to the stack of plies, and subjecting the stack of plies to a temperature and pressure cycle in an autoclave. The starting material is a laminate material of resin matrix reinforced with a fiber material. The matrix has a core layer of semi-crystalline thermoplastic resin and a pair of outer layers of amorphous thermoplastic resin arranged on opposite sides of the core layer. The glass transition temperature of the amorphous thermoplastic resin is below the melting point of the semi-crystalline thermoplastic resin. The autoclave temperature cycle heating rapidly the stack of plies to a working temperature above the transition temperature, but below the melting point, keeping the stack of plies at the working temperature during a time period for compaction alone; and cooling the stack of plies.