Heat treatment during composite extruded spring steel wire reinforced EN AW-6082

To increase the specific yield strength and the ultimate tensile strength of a unidirectionally spring steel wire - reinforced composite extruded aluminium alloy (AlMgSi1) matrix composite, investigations of heat treatment states T4 and T6 have been carried out. With respect to the quench sensitivity of the matrix material used and to reduce processing time to avoid unintended interfacial reactions, a setup for direct water quenching at the extrusion press was used and compared to air quenched extrusion profiles. The mechanical investigations showed increased ultimate tensile strength and offset yield strength for water quenched unreinforced and reinforced specimen. The deformation behaviour showed a distinct plateau region where matrix and wire deform plastically which can be explained by multiple necking of the reinforcing element. The characteristic of this region is strongly influenced by the heat treatment state. In order to characterize the interfacial properties, push-out tests were performed. Optical micrographs showed that debonding between matrix and reinforcing element mainly takes place within the matrix material. Therefore the measured debonding shear strength is strongly influenced by the heat treatment state.