Mechanical Investigations on Composite Peened Aluminium

Abstract

Composite peening describes a novel approach based on the micro peening process. By composite peening, particles can be introduced into near-surface regions of metallic base materials. The proportion of the reinforcement phase decreases gradually with increasing distance to the surface. These so-called Functionally Graded Metal Matrix Composites (FGMMC) are characterised by a multitude of different characteristics, such as material combination, particle density, particle gradient and particle size, and a resulting broad range of properties. The composite material produced by this method promises a high application potential for lightweight, wear resistant and cyclically stressed structural components.

EN AW–1050 was selected as matrix material and alumina as abrasive respectively reinforcement material. Additional abrasives such as silicon carbide and tungsten carbide were also investigated. By varying the process parameters, such as temperature and pressure, the influence on the particle density and the particle gradient was evaluated. Penetration depths up to 30 µm could be observed at high homologous temperatures. The peening process might cause open structures near the surface, the sample were subsequently deep rolled. In addition, this process reduces the surface roughness.

Ensuing mechanical characterisation focused on bending tests. An increase in the flexural strength of the composite material compared to the base material could be observed.