EFFECT OF PRESSURE ROLLING ON THE RESIDUAL-STRESS STATE OF A PARTICULATE-REINFORCED METAL-MATRIX COMPOSITE

The large difference between the coefficients of thermal expansion of the matrix alloy and the particle in a metal matrix composite gives ri se to residual stresses in the material. In the present work, the effe ct of pressure rolling on the residual stress state of a silicon carbi de particle-reinforced 2014 aluminium alloy has been investigated. The three-dimensional stress state measured in both phases-matrix and rei nforcement-has been determined using an X-ray diffraction technique. A twofold effect of pressure rolling on the residual stresses was obser ved. On the one hand, compressive macrostresses as large as - 250 MPa were induced. On the other hand a significant reduction in pseudo-macr ostresses was measured where the plastic deformation reaches a maximum . A modified Eshelby model was used to predict quantitatively and qual itatively the residual microstresses after heat treatment and pressure rolling respectively.